We’ve got the Power.
HIGH POWER WHITE LIGHT
CONSTANT CURRENT
LED-DRIVERS
MICROSIZE PCB MOUNT
SAFETY APPROVED
AC-DC MODULES
DROP IN REPLACEMENT FOR
3-PIN REGULATORS (78 SERIES)
SWITCHING REGULATORS
EFFICIENCIES UP TO 97%
100% POWER. NO DERATING.
HIGH EFFICIENCY HIGH TEMP.
DC-DC POWER MODULES
NEW!
Application Notes 2009
The POWERLINE PLUS uses ICE Technology. A combination of techniques
to minimise internal heat dissipation and maximise the heat transfer to
ambient to create a new converter series which offers high end performance
at a price which is significantly lower than conventional specialist converters.
RECOM - Green high-efficiency power solutions. SAVE ENERGY. NOW.
From -45°C up to 100°C Full Load Operating Temperature Built-in EN55022/FCC Class B EMC Filter
Up to 3kVDC Isolation Compact Size, Standard Pinouts Efficiency above 90% Single & Dual Outputs
2:1and4:1 Input Voltage Ranges 20W, 30W, 40W or 50W DC-DC Power Packages
POWERLINEPLUS
100% DC-DC Power. No derating.
POWERLINEPLUS
100% DC-DC Power. No derating.
www.recom-international.com A-1
2009
CHOOSING THE RIGHT CONVERTER: A GUIDE for DC/DC Converters
Step 1: Do you need Isolation? (An isolated converter has outputs that are floating and not
connected to the inputs i.e. they are galvanically isolated)
No isolation needed: Check our Innoline parts first (R-78 series, R-5xxx, R-6xxx and
R-7xxx series)
Isolation needed: decide whether you need 1kVDC/1 sec (standard) or 1.6VDC/
1 sec, 2kVDC/1 sec, 3kVDC/1 sec, 4kVDC/1 sec, 5.2kVDC/1 sec or 6kVDC/1 sec.
Step 2: Decide on the output voltage and number of outputs: single, dual bipolar (+/-), dual
isolated or triple.
It is also important to decide whether the output voltage needs to be regulated or
unregulated.
Unregulated converters are offered standard without short circuit protection or
optionally with short circuit protection (option /P)
All Series are available with single outputs.
Please note that a dual output converter can be used as a single output by leaving
the common pin unconnected i.e. +/-5V = 10V, +/-12V = 24V, +/-15V = 30V, etc.
Step 3: Decide on the output current. The output voltage times the output current gives the
output power of the converter in Watts.
DC/DC converters are designed to run at full load, so only round up the power if a
suitable converter is not available.
e.g. 5V @ 150mA = 0.75W = 1W converter.
e.g. +/-15V @ +/-1A = 30W = 30W converter.
Step 4: Decide on the input voltage. Standard input voltage ranges are:
3.3, 5, 9, 12, 15, and 24VDC with +/-10% tolerance
4.5 ~ 9V, 9 ~ 18V, 18 ~ 36V and 36 ~ 72VDC with 2:1 input voltage range
9 ~ 36V and 18 ~ 72VDC with 4:1 input voltage range.
Step 5: Decide on the case style and pin-out. Many Recom series are available in either
through hole or surface mount styles and with several pin-out options, including
Remote On/Off Control.
Step 6: Use either the Selection guide or Contents guide at the start of each section to
find the most appropriate converter.
REMEMBER: THERE IS AN INTERACTIVE SELECTION GUIDE ON OUR WEBSITES
Go to WWW.RECOM-INTERNATIONAL.COM then click on PRODUCT SEARCH
Go to WWW.RECOM-POWER.COM then click on PRODUCT SEARCH: SPEC BY STEP
Application Notes
A-2 www.recom-electronic.com
2009
2009
SPECIFICATION CHECKLIST
Use this checklist to help you define your specification. If you can’t find a converter that fulfils your
needs then call us, fax us, e-mail us or use our Web Sample Enquiry link and we will find the best
match for you.
1. Non-Isolated Isolation Required _____kVDC or ____kVAC
2. Single Output Dual Bipolar Output Other:
Output Voltages (V) _____ /______/______
Output Currents (A) _____/______/______
3. Total Output Power (V x A) _________________
4. Regulated Unregulated
5. Short Circuit Protection: No Yes
6. Remote Control Pin: No Yes
7. Output Voltage Trim: No Yes
8. Input Voltage: minimum ______ maximum ______
9. Mounting Style: Through Hole SMD
Single-In-Line Pins SIP4 SIP6 SIP7 SIP8 SIP12
Dual-In-Line Pins DIP8 DIP14 DIP16 DIP24 - Pinout? A_B_C_
Standard Brick 1” x 1” 1” x 2” 1.6” x 2” 2” x 2”
Case Style: Metal Case Plastic Case Open Frame
10. Certifications Required: None EN 60950-1 EN 60601-1 UL 60950-1
11. Operating Temperature Range: minimum ______ maximum ______
12. Heatsink required : No Yes
13. Other Requirements:________________________________________
REMEMBER: THERE IS AN INTERACTIVE SELECTION GUIDE ON OUR WEBSITES
Go to WWW.RECOM-INTERNATIONAL.COM then click on PRODUCT SEARCH
Go to WWW.RECOM-POWER.COM then click on PRODUCT SEARCH: SPEC BY STEP
Application Notes
www.recom-international.com A-3
2009
2009
ECONOLINE (General Apps.)
●TTeerrmmiinnoollooggyy
Input Range
Load Regulation
Line Voltage Regulation
Output Voltage Accuracy
Input and Output Ripple and Noise
Input to Output Isolation
Insulation Resistance
Efficiency at FulI Load
Temperature Drift
Switching Frequency
No Load Power Consumption
Isolation Capacitance
Mean Time Between Failure (MTBF)
Noise
Operating Temperature Range
Calculation of Heatsinks
●●IIssoollaattiioonn
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●●IIssoollaattiioonn mmooddee iinn IIGGBBTT DDrriivveerr CCiirrccuuiittss
●Connecting DC-DC Converters in Series
●Connecting DC-DC Converters in Parallel
●Chaining DC-DC Converters
●●FFiilltteerriinngg
Output Filtering Calculation
●●LLiimmiittiinngg IInnrruusshh CCuurrrreenntt
●●MMaaxxiimmuumm OOuuttppuutt CCaappaacciittaannccee
●●SSeettttlliinngg TTiimmee
●●IIssoollaattiioonn CCaappaacciittaannccee aanndd LLeeaakkaaggee CCuurrrreenntt
●●AApppplliiccaattiioonn EExxaammpplleess
OOvveerrllooaadd PPrrootteeccttiioonn
IInnppuutt VVoollttaaggeeDDrroopp--OOuutt ((bbrroowwnn--oouuttss))
No Load Over Voltage Lock-Out
Long Distance Supply Lines
LCD Display Bias
Pre- and Post Regulation
EIA-232 Interface
3V/5V Logic Mixed Supply Rails
Isolated Data Acquisition System
●●EEMMCC CCoonnssiiddeerraattiioonnss
PPoowweerr SSuuppppllyy CCoonnssiiddeerraattiioonnss
IInntteerrpprreettaattiioonn ooff DDCC--DDCC CCoonnvveerrtteerr EEMMCC DDaattaa
Conducted and Radiated Emissions
LLiinnee IImmppeeddaanncceeSSttaabbiilliissaattiioonn NNeettwwoorrkk ((LLIISSNN))
Shielding
Line Spectra of DC-DC Converters
●●Temperature Performance of DC-DC Converters
●●Transfer Moulded (SMD) DC-DC Converters
PPrroodduuccttiioonn GGuuiiddeelliinnee AApppplliiccaattiioonn NNoottee
CCoommppoonneenntt MMaatteerriiaallss
CCoommppoonneenntt PPllaacceemmeenntt
CCoommppoonneenntt AAlliiggnnmmeenntt
SSoollddeerr PPaadd DDeessiiggnn
SSoollddeerr RReeffllooww PPrrooffiillee
Recommended Solder Reflow Profile
Adhesive Requirements
Adhesive Placement
Cleaning
Vapour Phase Reflow Soldering
●●TTiinn WWhhiisskkeerr MMiittiiggaattiioonn
INNOLINE
●EMC Filter Suggestion
●●SSoofftt SSttaarrtt CCiirrccuuiitt
●Positve - to - Negative Converters
POWERLINE DC-DC
●●EEMMCC FFiilltteerr SSuuggggeessttiioonn
●●GGeenneerraall TTeesstt SSeett--UUpp
●●IInnppuutt VVoollttaaggee RRaannggee
●●PPII FFiilltteerr
●●OOuuttppuutt VVoollttaaggee AAccccuurraaccyy
●●VVoollttaaggee BBaallaannccee
●●LLiinnee RReegguullaattiioonnss
●●LLooaadd RReegguullaattiioonn
●●EEffffiicciieennccyy
●●SSwwiittcchhiinngg FFrreeqquueennccyy
●●OOuuttppuutt RRiippppllee aanndd NNooiissee
●●OOuuttppuutt RRiippppllee aanndd NNooiissee ((ccoonnttiinnuueedd))
●●TTrraannssiieenntt RReeccoovveerryy TTiimmee
●●CCuurrrreenntt LLiimmiittiinngg
●●FFoolldd BBaacckk CCuurrrreenntt LLiimmiittiinngg
●●IIssoollaattiioonn
●●BBrreeaakk--DDoowwnn VVoollttaaggee
●●TTeemmppeerraattuurree CCooeeffffiicciieenntt
●●AAmmbbiieennttTTeemmppeerraattuurree
●●OOppeerraattiinngg TTeemmppeerraattuurree RRaannggee
●●SSttoorraaggee TTeemmppeerraattuurree RRaannggee
●●OOuuttppuutt VVoollttaaggee TTrriimmmmiinngg
●●HHeeaatt SSiinnkkss
POWERLINE AC/DC
●Input Fuse
●Earthing
●External Filter
●Paralleling AC/DC Converters
●Chaining Converters
●DC Inputs
BLOCK DIAGRAMS
Transport Tubes & Reels
Contents
Application Notes
DC-DC Converter Applications
A-4 www.recom-electronic.com
2009
The data sheet specification for DC-DC con-
verters contains a large quantity of information.
This terminology is aimed at ensuring that the
user can interpret the data provided correctly
and obtain the necessary information for their
circuit application.
Input Range
The range of input voltage that the device can
tolerate and maintain functional performance
over the Operating Temperature Range at full
load.
Load Regulation
The change in output voltage over the speci-
fied change in output load. Usually specified as
a percentage of the nominal output voltage, for
example, if a 1V change in output voltage is
measured on a 12V output device, load voltage
regulation is 8.3%. For unregulated devices
the load voltage regulation is specified over
the load range from 10% to 100% of full
load.
Line Voltage Regulation
The change in output voltage for a given
change in input voltage, expressed as percen-
tages. For example, assume a 12V in-put, 5V
output device exhibited a 0.5V change at the
output for a 1.2V change at the input, line
regulation would be 1%/1%.
Output Voltage Accuracy
The proximity of the output voltage to the
specified nominal value. This is given as a
tolerance envelope for unregulated devices
with the nominal input voltage applied. For ex-
ample, a 5V specified output device at 100%
load may exhibit a measured output voltage of
4.75V, i.e. a voltage accuracy of –5%).
Input and Output Ripple and Noise
The amount of voltage drop at the input, or
output between switching cycles. The value of
voltage ripple is a measure of the storage
ability of the filter capacitors. The values given
in the datasheets include the higher frequency
Noise interference superimposed on the ripple
due to switching spikes.The measurement is
limited to 20MHz Bandwidth.
Input to Output Isolation
The dielectric breakdown strength test between
input and output circuits. This is the isolation
voltage the device is capable of withstanding
for a specified time, usually 1 second (for more
details see chapter “Isolation Voltage vs. Rated
Working Voltage”).
Insulation Resistance
The resistance between input and output
circuits. This is usually measured at 500V DC
isolation voltage.
Efficiency at FulI Load
The ratio of power delivered from the device to
power supplied to the device when the part is
operating under 100% load conditions at 25°C.
Temperature Drift
The change in voltage, expressed as a
percentage of the nominal, per degree change
in ambient temperature. This parameter is
related to several other temperature dependent
parameters, mainly internal component drift.
Switching Frequency
The nominal frequency of operation of the
switching circuit inside the DC-DC converter.
The ripple observed on the input and output
pins is usually twice the switching frequency,
due to full wave rectification and the push-pull
configuration of the driver circuit.
No Load Power Consumption
This is a measure of the switching circuits
power cunsumption; it is determined with zero
output load and is a limiting factor for the total
efficiency of the device.
Isolation Capacitance
The input to output coupling capacitance. This
is not actually a capacitor, but the parasitic
capacitive coupling between the transformer
primary and secondary windings. Isolation
capacitance is typically measured at 1 MHz to
reduce the possibility of the on-board filter
capacitors affecting the results.
Mean Time Between Failure (MTBF)
RECOM uses MIL-HDBK-217F standard for
calculation of MTBF values for +25°C as well as
for max. operating temperature and 100% load.
When comparing MTBF values with other
vendor's products, please take into account the
different conditions and standards i.e. MIL-
HDBK-217E is not as severe and therefore values
shown will be higher than those shown by RECOM.
(1000 x 10³ hours =1000000 hours = 114 years!)
These figures are calculated expected device
lifetime figures using the hybrid circuit model of
MIL-HDBK-217F. POWERLINE converters also
can use BELLCORE TR-NWT-000332 for
calculation of MTBF. The hybrid model has
various accelerating factors for operating
environment (πE), maturity (πL), screening (πQ),
hybrid function (πF) and a summation of each
individual component characteristic (λC).
The equation for the hybrid model is then given
by:
λ= Σ(NCλC) (1 + 0.2πE) πLπFπQ
(failures in 106hours)
The MTBF figure is the reciprocal of this value.
In the data sheets, all figures for MTBF are
given for the ground benign (GB) environment
(πE = 0.5); this is considered the most
appropriate for the majority of applications in
which these devices are likely to be used.
However, this is not the only operating
environment possible, hence those users
wishing to incorporate these devices into a
more severe environment can calculate the
predicted MTBF from the following data.
The MIL-HDBK-217F has military environ-
ments specified, hence some interpretation of
these is required to apply them to standard
commercial environments. Table 1 gives
approximate cross references from MIL-HDBK-
217F descriptions to close commercial equi-
valents. Please note that these are not implied
by MIL-HDBK-217F, but are our interpretation.
Also we have reduced the number of environ-
ments from 14 to 6, which are most appro-
priate to commercial applications. For a more
detailed understanding of the environments
quoted and the hybrid model, it is
recommended that a full copy of MIL-HDBK-
217F is obtained.
It is interesting to note that space flight and
ground benign have the same environment
factors. It could be suggested that the act
of achieving space flight should be the
determining environmental factor (i.e. missile
launch).
The hybrid model equation can therefore be
rewritten for any given hybrid, at a fixed
temperature, so that the environmental factor
is the only variable:
λ = k (1 + 0.2 πE)
The MTBF values for other environment factors
can therefore be calculated from the ground
benign figure quoted at each temperature point
in the data book. Hence predicted MTBF
figures for other environments can be calcula-
ted very quickly. All the values will in general
be lower and, since the majority of the mobile
environments have the same factor, a quick
divisor can be calculated for each condition.
Therefore the only calculation necessary is to
devide the quoted MTBF fig. by the divisor
given in table 2.
Terminology
DC-DC Converter Applications
www.recom-international.com A-5
2009
Environ- πEMIL-HDBK-271F Commercial Interpretation
ment Symbol Description or Examples
Ground GB Non-mobile, temperature and Laboratory equipment, test
Benign humidity controlled environments instruments, desktop PC's,
readily accessible to maintenance static telecomms
Ground GM Equipment installed in wheeled or In-vehicle instrumentation,
Mobile tracked vehicles and equipment mobile radio and telecomms,
manually transported portable PC's
Naval NS Sheltered or below deck Navigation, radio equipment
Sheltered equipment on surface ships or and instrumentation below
submarines deck
Aircraft AIC Typical conditions in cargo Pressurised cabin compart-
Inhabited compartments which can be ments and cock-pits, in flight
Cargo occupied by aircrew entertainment and non-safety
critical applications
Space SF Earth orbital. Vehicle in neither Orbital communications satel-
Flight powered flight nor in atmospheric lite, equipment only operated
re-entry once in-situ
Missile ML Severe conditions relating Severe vibrational shock and
Launch to missile launch very high accelerating forces,
satellite launch conditions
TTaabbllee 11:: IInntteerrpprreettaattiioonn ooff EEnnvviirroonnmmeennttaall FFaaccttoorrssFFiigguurree 11:: SSttaannddaarrdd IIssoollaatteedd CCoonnffiigguurraattiioonnss
0V
+VO
-VO
DC
GND
DC
GND
DC
DC
0V
+VO
(VO+VIN)
VCC
0V
DC
-VO
DC
+VO
GND
VCC
VCC
FFiigguurree 22:: AAlltteerrnnaattiivvee SSuuppppllyy CCoonnffiigguurraattiioonnss
b) Non-lsolated Negative Rail
a) Non-lsolated Dual Rails
c) Dual Isolated Outputs (U/T)
GND DC
DC
0V2
DC
-VO
DC
0V
+VO
VO
DC
GND
GND
VIN DC
VIN 0V
VIN
VO2
0V1
VO1
c) Twin Isolated Outputs
b) Dual Output
a) Single Output
Noise
Input conducted noise is given in the line
conducted spectra for each DC-DC converter
(see EMC issues for further details). Noise is
affected significantly by PCB layout, measure-
ment system configuration, terminating
impedance etc., and is difficult to quote
reliably and with any accuracy other than via a
spectrum analysis type plot. There will be some
switching noise present on top of the ripple,
however, most of this is easily reduced by use
of small capacitors or filter inductors, as shown
in the application notes.
Operating temperature range:
Operating temperature range of the converter
is limited due to specifications of the
components used for the internal circuit of the
converter.
The diagram for temperature derating shows
the safe operating area (SOA) within which the
device is allowed to operate. At very low
temperatures, the specifications are only
guaranteed for full load.
Up to a certain temperature 100% power can
be drawn from the device, above this tempera-
ture the output power has to be less to en-
sure function and guarantee specifications over
the whole lifetime of the converter.
These temperature values are valid for natural
convection only. If the converter is used in a
closed case or in a potted PCB board, higher
temperatures will be present in the area around
thermal converter because the convection may
be blocked.
If the same power is also needed at higher
temperatures either the next higher wattage
series should be chosen or if the converter has
a metal case, a heatsink may be considererd.
Please refer to the Powerline Application Notes
Section for more information on thermal
impedance and heatsinking.
Environment πEπEDivisor
Symbol Value
Ground Benign GB 0.5 1.00
Ground Mobile GM 4.0 1.64
Naval Sheltered GNS 4.0 1.64
Aircraft
Inhabited AIC 4.0 1.64
Cargo
Space Flight SF 0.5 1.00
Missile Launch ML 12.0 3.09
TTaabbllee 22:: EEnnvviirroonnmmeennttaall FFaaccttoorrss
DC-DC Converter Applications
A-6 www.recom-electronic.com
2009
The graph and table above show the requirements from IEC950. According to our experience and in-house tests, we can offer the following conversion ta-
bles:
Isolation Test Voltage Isolation Test Voltage Isolation Test Voltage
(1 second) (1 minute) (1 minute)
500 VDC 400 VDC 250 VAC
1000 VDC 800 VDC 500 VAC
1500 VDC 1200 VDC 750 VAC
2000 VDC 1600 VDC 1000 VAC
2500 VDC 2000 VDC 1250 VAC
3000 VDC 2400 VDC 1500 VAC
4000 VDC 3200 VDC 2000 VAC
5000 VDC 4000 VDC 2500 VAC
6000 VDC 4800 VDC 3000 VAC
Table 1 : D.C. Isolation Voltage test vs different conditions
Isolation
One of the main features of the majority of
Recom DC-DC converters is their high galvanic
isolation capability. This allows several variations
on circuit topography by using a single DC-DC
converter.
The basic input to output isolation can be used
to provide either a simple isolated output power
source, or to generate different voltage rails,
and/or dual polarity rails (see figure 1).
These configurations are most often found in
instrumentation, data processing and other
noise sensitive circuits, where it is necessary
to isolate the load and noise presented to the
local power supply rails from that of the entire
system. Usually local supply noise appears as
common mode noise at the converter and does
not pollute the main system power supply rails.
The isolated positive output can be connected
to the input ground rail to generate a negative
supply rail if required. Since the output is
isolated from the input, the choice of reference
voltage for the output side can be arbitrary, for
example an additional single rail can be
generated above the main supply rail, or offset
by some other DC value (see figure 2).
Regulated converters need more consideration
than the unregulated types for mixing the
reference level. Essentially the single supply rail
has a regulator in its +Vout rail only, hence
referencing the isolated ground will only work if
all the current return is through the DC-DC and
not via other external components (e.g. diode
bias, resistor feed). Having an alternative return
path can upset the regulation and the
performance of the system may not equal that
of the converter.
Isolation Voltage vs. Rated Working Voltage
The isolation voltage given in the datasheet is
valid for 1 second flash tested only.
If a isolation barrier is required for longer or
infinite time the Rated Working Voltage has to
be used.
Conversion of Isolation Voltage to Rated
Working Voltage can be done by using this
table or graph.
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TTaabbllee 22:: TTyyppiiccaall BBrreeaakkddoowwnn VVoollttaaggee RRaattiin
nggss AAccccoorrddiinngg ttoo IIEECC995500
Isolation Test Voltage (V) Rated Working Voltage (V)
1000 130
1500 230
3000 1100
6000 3050
01234567
Rated Working Voltage (kV)
Isolation Test Voltage (kV)
12
10
8
6
4
2
0
DC-DC Converter Applications
www.recom-international.com A-7
2009
Isolation Test Voltage Isolation Test Voltage Isolation Test Voltage
(1 second) (1 minute) (1 minute)
500 VAC 350 VAC 565 VDC
1000 VAC 700 VAC 1130 VDC
1500 VAC 1050 VAC 1695 VDC
2000 VAC 1400 VAC 2260 VDC
2500 VAC 1750 VAC 2825 VDC
3000 VAC 2100 VAC 3390 VDC
4000 VAC 2800 VAC 4520 VDC
5000 VAC 3500 VAC 5650 VDC
6000 VAC 4200 VAC 6780 VDC
Table 2 :A.C. Isolation Voltage test vs different conditions
Isolation mode in IGBT driver circuits
An application for DC/DC converters is to isolate driver circuits for IGBT stacks. In these applications, the maximum DC voltage applied across the
isolation gap is not the only factor to be considered because the highly dynamic switching waveforms are an additional stressing factor (typical
switching transients can exceed 20kV/µs.) Taking into account that both factors mean a permanent stress on the converter, it is recommended to
over specify the converter in terms of isolation voltage and coupling capacitance.
Even if a 3kVDC product seems to be appropriate if you just look at the rated working voltage that is required, it is still recommended to choose a
product which is specified to 5.2kVDC or 6kVDC to also cover the high dv/dt rates. The higher the isolation voltage rating for a DC/DC converter is,
the lower the coupling (isolation) capacitance and a low coupling capacitance is essential in AC or highly dynamic switched DC usage. This will
ensure a safe usage and avoid a shortened lifetime in such a highly demanding situation.
In the example below, A RP-0524S is used to provide a 5200V isolated supply for the high side drivers and a second, non-isolated converter is
used to boost the 5V supply voltage up to 15V for the low side drivers.
DC-DC Converter Applications
A-8 www.recom-electronic.com
2009
Connecting
DC-DC Converters in Series
Galvanic isolation of the output allows multiple
converters to be connected in series, simply by
connecting the positive output of one converter
to the negative of another (see figure 3). In this
way non-standard voltage rails can be
generated, however, the current output of the
highest output voltage converter should not be
exceeded.
When converters are connected in series,
additional filtering is strongly recommended, as
the converters switching circuits are not
synchronised. As well as a summation of the
ripple voltages, the output could also produce
relatively large beat frequencies. A capacitor
across the output will help, as will a series
inductor (see filtering).
Connecting
DC-DC Converters in Parallel
Connecting the outputs of DC/DC converters in
parallel is possible but not recommended.
Usually DC/DC converters have no possibility
to balance out the output currents.
So there is potential danger that if the loading
is asymmetrical, that one of the converters
starts to be overloaded while the others have to
deliver less current. The over-loaded
converter may then drop out of circuit leading
to power supply oscillation.
The only possibility to balance out the
individual currents is to use a special balance
function (like in R-5xxx) or use converters with
SENSE function and additional load-share
controllers (as can be done for the RP40-SG
and RP60-SG, for example). Refer to figure
5 below.
If two or more converters are operated from a
common supply voltage (inputs in parallel),
then input decoupling via LC-filters is
recommended (see input filters in figure 5).
This helps to avoid hard-to-handle conducted
EMI caused by totally un-synchronized
oscillators. Also inrush current peaks are
lowered. Having several smaller filters, one
for each converter, is recommended instead of
using one common filter for all converters, as
this helps to reduce the possibility of the
converters beating against each other.
Chaining
DC-DC Converters
Connecting the output of one DC/DC converter
to the input of a second converter is some-
times a very useful technique. For example, the
benefits of the very wide input voltage range
of the innoline series can be combined with the
high isolation of the econoline series to create
a combination converter which is both isolated
and with an exceptionally wide 7:1 input
voltage range.
Similarly, an isolated DC/DC converter can be
used to power a R-78 switchning regulator to
provide dual positive outputs with non-
standard voltages.
In every case, some care has to be taken
concerning the inrush current of the second
converter in the chain. If the peak inrush
current is too high, then then the first
converter in the chain may not start up.
The solution to this problem is to add some
capacitance to supply the peak inrush current
and/or to delay the start-up of the second
converter in the chain.
Figure 5a shows some typical examples.
DC
DC
DC
DC
Vcc
+Vo
2Vo
0V
0V
+Vo
GND
FFiigguurree 33:: CCoonnnneeccttiinngg DDCC--DDCC CCoonnvveerrtteerrss iinn SSeerriieess
Vcc
GND
DC
DC
DC
DC
+V
0V
Balance
Link
FFiigguurree 44:: PPaarraalllleelleedd DDCC--DDCC CCoonnvveerrtteerrss wwiitthh BBaallaannccee
FFuunnccttiioonn..
FFiigguurree 55:: PPaarraalllleelleedd DDCC--DDCC CCoonnvveerrtteerrss u
ussiinngg LLooaadd SShhaarree CCoonnttrroolllleerrss
+Vout
-Vout
+Sense
-Sense
+Vout
-Vout
+Sense
-Sense
RADJ
RSENSE
RADJ
RSENSE
Sense
-Share
+Share
-Share
+Share
-Share
Connected
to System
GND
Sense
ADJ VCC
VCC
ADJ
Load Share
Control
Load Share
Control
DC/DC
Converter 2
DC/DC
Converter 1
System
GND
System
VCC
FFiigguurree 55aa:: CChhaaiinneedd DDCC--DDCC CCoonnvveerrtteerr EExxaammpplleess
DC
DC
Vcc = 5V
+Vo
0V
GND
R-783.3
-0.5
REC5-0512SRW/H6/A
+12V
-Vo
10µ +3.3V
DC
DC
Vcc = 9-39V
+Vo0V
GND
RP15-2415SAW
+15V
-Vo
DC
DC +5V
RP08-1205DA
-5V
CTRL
RP08 starts up after delay
C1 provides inrush start up current
C1
DC-DC Converter Applications
www.recom-international.com A-9
2009
Filtering
When reducing the ripple from the converter, at
either the input or the output, there are se-
veral aspects to be considered. Recom re-
commend filtering using simple passive LC
networks at both input and output (see figure
6). A passive RC network could be used,
however, the power loss through a resistor is
often too high.The self-resonant frequency of
the inductor needs to be significantly higher
than the characteristic frequency of the
device (typically 1OOkHz for Recom DC-DC
converters). The DC current rating of the
inductor also needs consideration, a rating of
approximately twice the supply current is
recommended.
The DC resistance of the inductor is the final
consideration that will give an indication of
the DC power loss to be expected from the
inductor.
Output Filtering calculation:
Calculating of the filtering components can be
done using
This frequency should be significant lower than
the switching frequency of the converter.
Example - RC series:
Operating frequency = 85kHz max.
then, fc=10 % of 85 kHz = 8,5 kHz
However, depending on your application design
and loadsituation may interfer with the
calculated filter so testing in the final
application and re-adjustment of the
component’s values may be necessary.
When choosing a value for the filtering capacitor
please take care that the maximum capacitive
load is within the specifications of the converter.
Common Mode Chokes
Better results in filtering can be achieved if
common mode chokes are used instead of a
single choke.
Common mode chokes are multiple chokes
sharing a core material so the common mode
rejection (Electrical noise which comes through
one power line and returns to the noise source
through some type of ground path is common
mode noise.) is higher.
Please refer to our page "Common Mode
Chokes for EMC" also part of these application
notes. These can be used for input filtering as
well as for the output side.
Limiting Inrush Current
Using a series inductor at the input will limit
the current that can be seen at switch on
(see figure 7).
If we consider the circuit without the series
inductor, then the input current is given by;
i = Vexp (– t )
RRC
When the component is initially switched on
(i.e. t=O) this simplifies to;
i = V
R
This would imply that for a 5V input, with say
50mOhm track and wire resistance, the inrush
current could be as large as 1OOA. This could
cause a problem for the DC-DC converter.
A series input inductor therefore not only filters
the noise from the internal switching circuit,
but also limits the inrush current at switch on.
A typical value for an input inductor used to
reduce the inrush current is 1mH or higher.
A typical value for an inductor used to filter the
input is 50-300µH. So although the circuit
diagram may look similar, the input inductors
have very different functions and different
values.
If a common mode choke is used as an inrush
current limiter, it has the added advantage over
a single inductor that the inrush currents flowing
in the two windings cancel out and the ferrite is
less likely to go into saturation.
Short Circuit Protection in
0.25W - 2W Econoline converters
In the low wattage, unregulated converter Port-
folio we offer continuous short circuit protec-
tion (option /P). Especially in applications where
the output of converters is connected via a plug
and socket to an external module, the chances
of having a short circuit across the output is
quite high. A conventional unregulated conver-
ter can withstand a short circuit across the out-
puts for only a limited time. The same condition
can occur with high capacitive loads if they have
a low ESR.
RECOM uses balancing between transformer
core saturation ratings and the maximum elec-
trical ratings of the switching transistors in the
primary side oscillator to create a converter that
can withstand a continuous short circuit
(<1 Ohm) across the outputs without failing.
However, this is NOT an overload protection.
If the coverters are over-loaded but not short
circuited, the converters may still overheat and
fail.
FFiigguurree 66:: IInnppuutt aanndd OOuuttppuutt FFiilltteerriinngg
FFiigguurree 77:: IInnppuutt CCuurrrreenntt && VVoollttaaggee aatt SSwwiittcchh OOnn
VIN
time
i = V
_
R
V
_
R
Voltage : V = Vin (1 – exp )
( )
–t
__
RC
Current : i = exp ( )
–t
__
RC
C0
1
LOUT
π
=
fc2
C0
1
LOUT
π
=
fc2
C0
1
LOUT
π
2
=
fc8,5 kHz =
for:
LOUT
=
470 H
µ
=
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
=
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
=π
π
C
0
11
(2 f )
c
2
L
OUT
(2 8,5 kHz)
2
470 uH 745 nF
DC-DC Converter Applications
A-10 www.recom-electronic.com
2009
Maximum Output Capacitance
A simple method of reducing the output ripple
is simply to add a large external capacitor. This
can be a low cost alternative to the LC filter
approach, although not as effective. There is,
however, also the possibility of causing start
up problems, if the output capacitance is too
large.
With a large output capacitance at switch on,
there is no charge on the capacitors and the
DC-DC converter immediately experiences a
large current demand at its output. The inrush
current can be so large as to exceed the
ability of the DC-DC converter, and the device
can go into current limit or an undefined mode
of operation. In the worst case scenario the
device continuously oscillates as it tries to
start, goes into overload shutdown and then
retries again.
The DC-DC converter may not survive if this
condition persists.
For the Powerline the maximum capacitive
loads are specified. For Econoline please refer
to the tables below.
If instead of single capacitors on outputs an
L-C-filter is used, the maximum capacitive load
can be higher because the choke is preventing
too high rising speed of the current peak.
However the practical maximum capacitive
load is dependent on the quality of the filter
and the ESR of the capacitors used.
Settling Time
The main reason for not fitting a series
inductor internally, apart from size constraints,
is that many applications require a fast switch
on time. When the input voltage is a fast ramp,
then the output can respond within 500µs of
the input reaching its target voltage (measured
on a range of RA/RB and RC/RD converters
under full output load without external filters).
The use of external filters and additional input
or output capacitance will slow this reaction
time. It is therefore left to the designer to
decide on the predominant factors important
for their circuit: settling time or noise
performance.
Isolation Capacitance
and Leakage Current
The isolation barrier within the DC-DC
converter has a capacitance, which is a
measure of the coupling between input and
output circuits. Providing this is the largest
coupling source, a calculation of the leakage
current between input and output circuits can
be calculated.
Single Output Dual Output
22µF max.
33µF max. 10µF max.
47µF max. 33µF max.
Max. capacitive load for unregulated Econoline models
Unregulated 0.25W
Unregulated 0.5W
Unregulated 1W
Regulated 0.5W
Unregulated 2W
Regulated 1W
Max. capacitive load
3.3V 2200µF
5.0V 1000µF
9.0V 470µF
12.0V 220µF
15.0V 120µF
±5.0V ±470µF
±9.0V ±220µF
±12.0V ±100µF
±15.0V ±68µF
Max. capacitive load for REC3 and REC5 series
3W , 5W
Single output
Dual output
Max. capacitive load
3.3V 3300µF
5.0V 2200µF
9.0V 680µF
12.0V 330µF
15.0V 220µF
±5.0V ±1000µF
±9.0V ±330µF
±12.0V ±160µF
±15.0V ±100µF
Max. capacitive load for REC7.5 series
7.5W
Single output
Dual output
DC-DC Converter Applications
www.recom-international.com A-11
2009
Assuming we have a known isolation capaci-
tance (Cis - refer to datasheet) and a known
frequency for either the noise or test signal,
then the expected leakage current (iL) between
input and output circuits can be calculated
from the impedance.
The general isolation impedance equation for a
given frequency (f) is given by:
Zf
= ___1___
j
2π
Cis
For an RB-0505D, the isolation capacitance is
18pF, hence the isolation impedance to a 50Hz
test signal is:
Z50
= ___1_______ = 177
M
Ω
j
2π50 18
pf
If using a test voltage of 1kVrms, the leakage
current is:
iL
= Vtest = _1000V_ = 5.65 µ
A
Zf
177
M
Ω
It can be easily observed from these simple
equations that the higher the test or noise
voltage, the larger the leakage current, also the
lower the isolation capacitance, the lower the
leakage current. Hence for low leakage
current, high noise immunity designs, high
isolation DC-DC converters should be selected
with an appropriate low isolation capacitance.
Application Examples
Overload Protection
Although the use of filtering will prevent
excessive current at power-on under normal
operating conditions, many of the lower cost
converters have no protection against an output
circuit taking excessive power or even going
short-circuit. When this happens, the DC-DC
converter will take a large input current to try
to supply the output. Eventually the converter
will overheat and destroy itself if this condition
is not rectified (short circuit overload duration
is only for 1s on a standard unregulated part).
There are several ways to prevent overload at
the outputs destroying the DC-DC converter.
The simplest being a straight forward fuse.
Sufficient tolerance for inrush current is required
to ensure the fuse does not blow on power-on
(see figure 8). Another simple scheme that
can be applied is a circuit breaker.
There is also the potential to add some
intelligence to the overload scheme by either
detecting the input current, or the output
voltage (see figure 9).
If there is an intelligent power management
system at the input, using a series resistor (in
place of the series inductor) and detecting the
voltage drop across the device to signal the
management system can be used. A similar
scheme can be used at the output to
determine the output voltage, however, if the
management system is on the input side, the
signal will need to be isolated from the
controller to preserve the system isolation
barrier (see figure 10).
There are several other current limiting techni-
ques that can be used to detect an overload
situation, the suitability of these is left to the
designer. The most important thing to consider
is how this information will be used. If the
system needs to signal to a controller the
location or module causing the overload, some
form of intelligence will be needed. If the device
simply needs to switch off, a simple fuse type
arrangement will be adequate.
Unregulated RECOM DC/DC converters usually
are short circuit protected only for a short time,
e.g. 1 second. By option they can be continous
short circuit protected (option /P), then their
design is able to withstand the high output
current in a short circuit situation without any
need for extra circuit protection. All Recom
DC-DC converters which include an internal
linear regulator have a thermal overload shut-
down condition which protects these devices
from excessive over-load.
If this condition is to be used to signal a power
management system, the most suitable
arrangement is the output voltage detector
(see figure 10a), since this will fall to near zero
on shut-down. Wide input range regulated
converters offer overload protection / short
circuit protection via an internal circuit that
interfers with the primary oscillator so the
switching is regulated back in situations of
overload or output short circuit.
DC
DC
GND
Fuse
VIN
FFiigguurree 88:: SSiimmppllee OOvveerrllooaadd PPrrootteeccttiioonn
DC
DC
DC
DC
Vcc
GND
R1
R2 Rgnd
Ilimit
Vcc
GND
Vout
Rin
FFiigguurree 99:: IInnppuutt MMoonniittoorreedd OOvveerrllooaadd PPrrootteeccttiioonn
a) Series Resistor for Input Current Measurement
b) Ground Current Monitor
Choose current limit (ILIMIT)
and ground resistor (RGND) so
that : 0.7V = RGND x ILIMIT.
DC-DC Converter Applications
A-12 www.recom-electronic.com
2009
FFiigguurree 1100 :: OOuuppuutt MMoonniittoorreedd OOvveerrllooaadd PPrrootteeccttiioonn
DC
DC
VCC
GND
+VO
OV
RD
VOL
ROOpto-Isolator
Opto-Isolated Power Good / Overload Detector
(On overload +VO falls and the LED switches off, the VOL. line is then pulled high.)
DC
DC
47µF
LIN
ZDX60
Output Circuit
FFiigguurree 1111 :: IInnppuutt VVoollttaaggee DDrroopp--oouutt
R2
DC
DC
R10%
DC
DC
R10%
FFiigguurree 1122:: NNoo LLooaadd oovveerr VVoollttaaggee LLoocckk--OOuutt
Input Voltage
Drop-Out (brown-outs)
When the input voltage drops, or is momentarily
removed, the output circuit would suffer similar
voltage drops. For short period input voltage
drops, such as when other connected circuits
have an instantaneous current demand, or
devices are plugged in or removed from the
supply rail while 'hot', a simple diode-capacitor
arrangement can prevent the output circuit
from being effected.
The circuit uses a diode feed to a large reservoir
capacitor (typically 47µF electrolytic), which
provides a short term reserve current source
for the converter, the diode blocking other
circuits from draining the capacitor over the
supply rail. When combined with an in-line
inductor this can also be used to give very
good filtering. The diode volt drop needs to be
considered in the power supply line under
normal supply conditions. A low drop Schottky
diode is recommended (see figure 11).
No Load Over Voltage Lock-Out
Unregulated DC-DC converters are expected to
be under a minimum of 10% load, hence
below this load level the output voltage is
undefined. In certain circuits this could be a
potential problem.
The easiest way to ensure the output voltage
remains within a specified tolerance, is to add
external resistors, so that there is always a
minimum 10% loading on the device (see
figure 12). This is rather inefficient in that 10%
of the power is always being taken by this load,
hence only 90% is available to the additional
circuitry.
Zener diodes on the output are another simple
method. It is recommended that these be used
with a series resistor or inductor, as when the
Zener action occurs, a large current surge may
induce signal noise into the system.
DC-DC Converter Applications
www.recom-international.com A-13
2009
Long Distance Supply Lines
When the supply is transmitted via a cable,
there are several reasons why using an isolated
DC-DC converter is good design prac-tice (see
figure 13). The noise pick up and EMC suscep-
tibility of a cable is high compared to a pcb
track. By isolating the cable via a DC-DC
converter at either end, any cable pick-up will
appear as common mode noise and should be
self-cancelling at the converters.
Another reason is to reduce the cable loss by
using a high voltage, low current power transfer
through the cable and reconverting at the
terminating circuit. This will also reduce noise
and EMC susceptibility, since the noise voltage
required to affect the rail is also raised.
For example, compare a system having a 5V
supply and requiring a 5V, 500mW output at a
remote circuit. Assume the connecting cable
has a 100 Ohm resistance. Using an RO-0505
to convert the power at either end of the cable,
with a 100mA current, the cable will lose 1W
(I2R) of power. The RO would not be suitable,
since this is its total power delivery; hence
there is no power available for the terminating
circuit. Using a RB-0512D to generate 24V and
a RO-2405S to regenerate the 5V, only a 21
mA supply is required through the cable, a
cable loss of only 44mW.
LCD Display Bias
A LCD display typically requires a positive or
negative 24V supply to bias the crystal. The
RO-0524S converter was designed specifically
for this application. Having an isolated OV out-
put, this device can be configured as a +24V
supply by connecting this to the GND input, or
a –24V supply by connecting the +Vo output to
GND (see figure 14).
Pre- and Post Regulation
The usefulness of many DC-DC converters can
be enhanced by pre- or post-regulation.
The usual input voltage range of a DC-DC
converter is either fixed, 2:1 or 4:1 depending
on the converter technology used inside the
device. Switching regulators have typically a
much wider input voltage range - up to 8:1,
but do not have the advantage of the DC-DC
converter’s galvanic isolation. By combining
the two techniques and using a switching
regulator as a pre-regulator, an ultra-wide
range, isolated DC-DC converter supply can be
built (see Figure 15a)
Post regulation is useful to combine the
advantages of a linear regulator’s low noise
output with the ability of a DC-DC converter to
boost a lower input voltage to a higher output
voltage.
In this example, a low cost RAA unregulated
converter is used to boost a 5V supply up to
10V so that a low drop out linear regulator can
produce a low noise, regulated 9V output.
EIA-232 Interface
In a mains powered PC often several supply
rails are available to power a RS232 interface.
However, battery operated PC’s or remote
equipment having a RS232 interface added
later, or as an option, may not have the supply
rails to power a RS232 interface. Using a
RB-0512S is a simple single chip solution,
allowing a fully EIA-232 compatible interface
to be implemented from a single 5V supply rail,
and only 2 additional components (see figure
16a).
FFiigguurree 1133:: LLoonngg DDiissttaannccee PPoowweerr TTrraannssffeerr
Vin
GND DC
DC DC
DC
Target Circuit
RO-2405RB-0512D Cable
DC
DC Liquid
Crystal
Display
RO-0524S
-24V
(up to 42mA)
FFiigguurree 1144:: LLCCDD DDiissppllaayy BBiiaass
FFiigguurree 1155aa:: PPrree--RReegguullaattiioonn EExxaammppllee
DC
DC
Vcc = 9~72VDC
+5V @ 400mA
GND
R-78HB05-0.5
Isolated Vout
RI-0505S
DC
DC
Vcc = 5V
+Vo
0V
GND
7805
LDO
RB-053.3D +5V
-Vo
<5µV
Low Noise
Regulated
5V Output
+6.6V
(Optional Link)
100n
2µ2
FFiigguurree 1155bb:: PPoosstt--RReegguullaattiioonn EExxaammppllee
DC-DC Converter Applications
A-14 www.recom-electronic.com
2009
3V/5V Logic Mixed Supply Rails
There has been a lot of attention given to new
l.C.'s and logic functions operating at what is
rapidly emerging as the standard supply level
for notebook and palmtop computers. The 3.3V
supply is also gaining rapid acceptance as the
defacto standard for personal tele-
communications, however, not all circuit
functions required are currently available in a
3.3V powered IC. The system designer there-
fore has previously had only two options
available; use standard 5V logic or wait until
the required parts are available in a 3.3V form,
neither being entirely satisfactory and the
latter possibly resulting in lost market share.
There is now another option, mixed logic
functions running from separate supply rails. A
single 3.3V line can be combined with a range
of DC-DC converters from Recom, to generate
voltage levels to run virtually any standard logic
or interface IC.
The Recom range includes dual output parts
for powering analogue bipolar and amplifier
functions (RB series), as well a single output
function for localised logic functions (RL/RM,
RN/RO series). A typical example might be a
RS232 interface circuit in a laptop PC using a
3.3V interface chip (such as the LT1330),
which accepts 3.3V logic signals but requires
a 5V supply (see figure 16b). Recom has another
variation on this theme and has developed two
5V to 3.3V step down DC-DC converters
(RL-053.3 and R0-053.3). These have been
designed to allow existing systems to start
incorporating available 3.3V l.C.’s without
having to redesign their power supply.
This is particularly important when trying to
reduce the overall power demand of a system,
but not having available all of the functions at
the 3.3V supply.
The main application for this range of devices
are system designers, who want to provide
some functionality that requires a higher
voltage than is available from the supply rail, or
for a single localised function. Using a fully
isolated supply is particularly useful in interface
functions and systems maintaining separate
analogue and digital ground lines.
DC
DC
RB-0512D
DB9S Connector
SN75C185
GND
VCC
+VO
-VO
OV
5V
+12V
EIA-232 Port
VDD
DCD
DSR
RX
RTS
TX
CTS
RI
DTR
FFiigguurree 1166aa:: OOppttiimmiisseedd RRSS223322 IInntteerrffaaccee
GND
3.3VCC
OV
3.3V
DC
DC
RL-3.305
3
1
8
7
VCC
+5V
GND
1µF +V -V 100nF
+
220nF
+
200nF
GND
RX1
TX1 TX1
RX1
LT1330
RS232
3.3V Logic
17
6
5
27
26
28
21
3
4
14
25
24
FFiigguurree 1166bb:: RRSS223322 IInntteerrffaaccee wwiitthh 33VV LLooggiicc
DC-DC Converter Applications
www.recom-international.com A-15
2009
FFiigguurree 1177:: IIssoollaatteedd SSeerriiaall AADDCC SSyysstteemm
ZN509
VCC
GND
DC
RH-0505
DC
5V +5V
47µH
1µF
+5V
1K2
470vF
AIN
Vref
CLK
Data
1K2
4K7
+5V
+5V
Status
CS
4K7
1K2
SFH610
Opto Isolators
4K7
1K2
5V
4K7
1K2
5V
Status
CLK
CS
Data
5V Logic Circuit
CCT1 CCT2
GND
VCC
PSU 3
CCT1 CCT2
GND
VCC
PSU 8
FFiigguurree 1188:: EElliimmiinnaattee LLooooppss iinn SSuuppppllyy LLiinnee
FFiigguurree 1199:: DDeeccoouuppllee SSuuppppllyy LLiinneess aatt LLooccaall BBoouunnddaarriieess
Power Supply Considerations
●Eliminate loops in supply lines (see figure 18).
●Decouple supply lines at local boundaries (use LC filters with low Q,
see figure 19).
●Place high speed sections close to the power line input, slow
speed sections furthest away (reduces power plane transients, see
figure 20).
●Isolate individual systems where possible (especially analogue
and digital systems) on both power supply and signal lines (see figure 21).
An isolated DC-DC converter can provide a significant benefit to help
reduce susceptibility and conducted emission due to the isolation of
both power rail and ground from the system supply. Recom primarily
uses toroidal transformers in our DC-DC converters and as such they
have negligible radiated EMI, but all DC-DC converters are switching
devices and as such will have a characteristic switching frequency,
which may need some additional filtering.
Interpretation of DC-DC Converter EMC Data
Electromagnetic compatibility (EMC) of electrical and electronic products
is a measure of electrical pollution. Throughout the world there are
increasing statutory and regulatory requirements to demonstrate the
EMC of end products. In Europe the EC directive 89/336/EEC requires
that any product sold after 1 January 1996 complies with a series of
EMC limits, otherwise the product will be prohibited from sale within
the EEC and the seller could be prosecuted and fined.
Although DC-DC converters are generally exempt from EMC restrictions
on the grounds that they are components, it is the belief of Recom that
information on the EMC of these components can help designers plan
ahead so that their end products can meet the relevant statutory EMC
requirements. It must be remembered however, that a DC-DC converter
is unlikely to be the only com-ponent in the power supply chain, hence
the information quoted needs interpretation by the circuit designer to
determine its impact on the final EMC performance of their system.
Isolated Data Acquisition System
Any active system requiring isolation will need a DC-DC converter to provide the power transfer for the isolated circuit. In a data acquisition circuit
there is also the need for low noise on the supply line; hence good filtering is required. The circuit shown (see figure 17) provides a very high
voltage isolation barrier by using an RH converter to provide the power isolation and opto isolators for the data isolation. An overall system isolation
of 2.5kV is achieved.
EMC Considerations:When used for isolating a local power supply and incorporating the appropriate filter circuits as illustrated in Fig. 17), DC-DC
converters can present simple elegant solutions to many EMC power supply problems. The range of fixed frequency DC-DC converters is
particularly suitable for use in EMC problem situations, as the stable fixed switching frequency gives easily characterised and easily filtered output.
The following notes give suggestions to avoid common EMC problems in power supply circuits.
CCT1 CCT2
GND
VCC
DC-DC Converter Applications
A-16 www.recom-electronic.com
2009
The notes given here are aimed at helping
the designer interpret the effect the DC-DC
converter will have on the EMC of their end
product, by describing the methods and ratio-
nale for the measurements made. Where
possible CISPR and EN standards have been
used to determine the noise spectra of the
components, however, all of the standards
reference to mains powered equipment and
interpretation of these specifications is
necessary to examine DC supplied devices.
Conducted and
Radiated Emissions
There are basically two types of emissions
covered by the EC directive on EMC: radiated
and conducted. Conducted emissions are
those transmitted over wire connecting circuits
together and covers the frequency spectrum
150kHz to 30MHz. Radiated are those emissions
transmitted via electromagnetic waves in air
and cover the frequency spectrum 30MHz to
1GHz.
Hence, the EC directive covers the frequency
spectrum 150kHz to 1GHz, but as two
separate and distinct modes of transmission.
The Recom range of DC-DC converters feature
toroidal transformers. These have been tested
and proved to have negligible radiated noise.
The low radiated noise is primarily due to
toroidal shaped transformers maintaining the
magnetic flux within the core, hence no
magnetic flux is radiated by design. Due to the
exceptionally low value of radiated emission,
only conducted emissions are quoted.
Conducted emissions are measured on the
input DC supply line. Unfortunately no
standards exist for DC supplies, as most
standards cover mains connected equipment.
This poses two problems for a DC supplied
device, firstly no standard limits can be directly
applied, since the DC supplied device does
not directly connect to the mains, also all
reference material uses the earth-ground as
a reference point. In a DC system often the OV
is the reference, however, for EMC purposes, it
is probably more effective to maintain the earth
as the reference, since this is likely to be the
reference that the shielding is connected to.
Consequently all measurements quoted are
referenced to the mains borne earth.
Line Impedance Stabilisation
Network (LISN)
It is necessary to ensure that any
measure-ment of noise is from the device
under test (DUT) and not from the supply to this
device. In mains connected circuits this is
important and the mains has to be filtered prior
to supply to the DUT. The same approach has
been used in the testing of DC-DC converters
and the DC supply to the converter was filtered,
to ensure that no noise from the PSU as
present at the measuring instrument.
A line impedance stabilisation network (LISN)
conforming to CISPR 16 specification is
connected to both positive and negative supply
rails and referenced to mains earth (see figure
22). The measurements are all taken from the
positive supply rail, with the negative rail
measurement point terminated with 50 Ohm to
impedance match the measurement channels.
Power Input
Filter
P
S
U
High Speed
Circuit
Medium Speed
Circuit
Low Speed
Circuit
DC Circuit
Local
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CCT1
GND
VCC
DC
DC
CCT2
DC
DC
FFiigguurree 2211 :: IIssoollaattee IInnddiivviidduuaall SSyysstteemmss
–
+
LISN
LISN
DC
DC
To Spectrum Analyser
Power Supply 50Ω
Termination
Load
FFiigguurree 2222:: FFiilltteerreedd SSuuppppllyy ttoo DDCC--DDCC CCoonnvveerrtteerr
DC-DC Converter Applications
www.recom-international.com A-17
2009
Shielding
At all times the DUT, LlSN’s and all cables
connecting any measurement equipment,
loads and supply lines are shielded. The
shielding is to prevent possible pick-up on
cables and DUT from external EMC sources
(e.g. other equipment close by). The shielding
is referenced to mains earth (see figure 22).
Line Spectra of DC-DC Converters
All DC-DC converters are switching devices,
hence, will have a frequency spectra.
Fixed input DC-DC converters have fixed
switching frequency, for example the RC/RD
range of converters has a typical switching
frequency of 50kHz. This gives a stable and
predictable noise spectrum regardless of load
conditions.
If we examine the noise spectrum closely (see
figure 23) we can see several distinct peaks,
these arise from the fundamental switching
frequency and its harmonics (odd line spectra)
and the full rectified spectra, at twice the
fundamental switching frequency (even line
spectra). Quasi-resonant converters, such as
the Recom range, have square wave switching
waveforms, this produces lower ripple and a
higher efficiency than soft switching devices,
but has the drawback of having a relatively
large spectrum of harmonics.
The EC regulations for conducted interference
covers the bandwidth 150kHz to 30MHz.
Considering a converter with a 100kHz nominal
switching frequency, this would exhibit 299
individual line spectra. There will also be a
variation of absolute switching frequency with
production variation, hence a part with a 90kHz
nominal frequency would have an additional
33 lines over the entire 30MHz bandwidth.
Absolute input voltage also produces slight
variation of switching frequency (see figure
24). Hence, to give a general level of
conducted noise, we have used a 100kHz
resolution bandwidth (RBW) to examine the
spectra in the data sheets. This wide RBW
gives a maximum level over all the peaks,
rather than the individual line spectra. This is
easier to read as well as automatically
compensating for variances in switching
frequency due to production variation or
differences in absolute input voltage (see
figure 25).
The conducted emissions are measured under
full load conditions in all cases. Under lower
loads the emission levels do fall, hence full load
is the worst case condition for conducted line
noise.
Econoline Filters for Conducted
and Radiated Emissions
Econoline converters will meet the
requirements for FCC / EN55022 Class A and
Class B limits for conducted and radiated
emissions with the addition of an external filter.
The following filter circuit suggestions are
based on EMC tests carried out in an EMC test
facility on single converters. Different
component values or filter configurations may
be required if several converters share a
common supply, if different types of converter
are used together or if the supply voltage or
load is not placed close to the converters.
50
40
30
20
10
0
Frequency (kHz)
0246810
Input Voltage (V)
12 14
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FFiigguurree 2255 :: VV SSppeeccttrruumm
Frequency
100
80
60
40
20
100kHz 1MHz 10MHz 100MHz
0
Conducted Emission (dBuV)
FFiigguurree 2233:: IInnddiivviidduuaall LLiinnee SSppeeccttrraa
0
1
2
3
4
5
6
7
8
9
10
11
12
13
100
Frequency (kHz)
100
80
60
40
20
0
Conducted Emission (dBuV)
200 300 400 500
DC-DC Converter Applications
A-18 www.recom-electronic.com
2009
Econoline EMC Filter Suggestions: Low Power Regulated and Unregulated Converters
EN55022 Class A
(Omit C1, L1 and C3)
RM, RSS, RSD, RNM,ROM,
RO, RBM,RB,RE.RK, RH, RN,
RTS, RTD, RI, RD, RKZ,RJZ,
RZ, RSZ, RY
C2=3.3µF
RP, RxxPxx, RU, RxxP2xx,
RUZ, RV
C2=10µF
++Output
C1
Input
L1
C3
C2
EN55022 Class B
All 2:1 and 4:1
REC3-REC7.5
Converters
For details of CMC-08
common mode choke
refer to Powerline
application notes section
++
15µF
Output
10µF
Input
CMC-08
2.2nF-100nF
EN55022 Class B
RM, RSS, RSD, RNM,ROM, RO,
RBM,RB,RE.RK, RH, RN, RTS, RTD,
RI, RD, RKZ,RJZ, RZ, RSZ, RY
C1=10µF, L1 = 470µH, C2=4.7µF,
C3 = 2.2nF
RP, RxxPxx, RU, RxxP2xx, RUZ, RV
C1=10µF, L1 = 470µH, C2=10µF,
C3 = 2.2nF
EN55022 Class A
(omit C3)
RS0, RS, RW2
RS3, RW-S, RW-D, REC3-R
C1=10µF, L1 = 1mH, C2=10µF
EN55022 Class B
RS0, RS, RW2
RS3, RW-S, RW-D, REC3-R
C1=10µF, L1 = 1mH, C2=20µF,
C3 = 2.2nF
All capacitors are MLCC
2
1
43
C1 C2
C3
CMC-08
Ground
Plane
"A" Pinning
Econoline EMC Filter Suggestion: 3W - 7.5W Regulated Converters
Bottom View
www.recom-international.com A-19
2009
DC-DC Converter Applications
Temperature Performance
The temperature performance of the DC-DC
converters detailed in this book is always better
than the quoted operating temperature range.
The main reason for being conservative on the
operating temperature range is the difficulty of
accurately specifying parametric performance
outside this temperature range.
There are some limiting factors which provide
physical barriers to performance, such as the
Curie temperature of the core material used in
the DC-DC converter (the lowest Curie
temperature material in use at Recom is
125°C). Ceramic capacitors are used almost
exclusively in the DC-DC converters because
of their high reliability and extended life
properties, however, the absolute capacity of
these can fall when the temperature rises
above 85°C (i.e. the ripple will increase). Other
considerations are the power dissipation within
the active switching components, although
these have a very high temperature rating.
Their current carrying capacity derates as
temperature exceeds 100°C.
Therefore this allows the DC-DC converters
to be used above their specified operating
temperature, providing the derating of power
delivery given in the specification is adhered
to. Components operating outside the quoted
operating temperature range cannot be
expected to exhibit the same parametric
performance that is quoted in the specification.
An indication of the stability of a device can be
obtained from the change in its operating
frequency, as the temperature is varied (see
figure 26). A typical value for the frequency
variation with temperature is 0.5% per °C, a
very low value compared to other commercial
parts. This illustrates the ease of filtering of
Recom DC-DC converters, since the frequency
is so stable across load and temperature ranges.
Surface Mount DC-DC Converters
Production Guideline Application Note
The introduction by Recom of a new and
innovative method of encapsulating hybrid DC-
DC converters in a transfer moulded (TM)
epoxy molding compound plastic has enabled
a new range of surface mount (SMD) DC-DC
converters to be brought to market, which
addresses the component placement with
SOIC style handling.
With any new component there are of course
new lessons to be learned with the mounting
technology. With the Recom SMD DC-DC
converters, the lessons are not new as such,
but may require different production
techniques in certain applications.
Component Materials
Recom SMD converters are manufactured in a
slightly different way than the through-hole
converters. Instead of potting the PCB board
inside a plastic case with conventional epoxy
the whole package is molded around the PCB
board with epoxy molding compound plastic.
Open frame SMD parts have no moulding
compound and the case (when fitted) is
provided purely to allow the pick-amd-place
machine to be able to grip the part and to
provide a surface for the part number and
datecode. As the parts are nor encapsulated,
they have more freedom to expand and
contract which makes them ideal for vapour
phase reflow processes and allows greater
flexibility in the termperature profile.
All materials used in RECOM lead-free products
are ROHS compliant, thus the total amount
of the restricted materials (lead, mercury,
cadmium, hexavalent chromium, PBBs and
PBDEs) are below the prescribed limits.
Detailed chemical analysis reports are available.
Component Placement
Recom SMD DC-DC converters are designed
to be handled by placement machines in a
similar way to standard SOIC packages. The
parts are available either in tubes (sticks) or in
reels. The parts can therefore be placed using
machines with either vibrational shuttle, gravity
feeders, or reel feeders.The vacuum nozzle for
picking and placing the components can be the
same as used for a standard 14 pin or 18 pin
SOIC (typically a 5 mm diameter nozzle). An
increase in vacuum pressure may be
beneficial, due to the heavier weight of the
hybrid compared to a standard SOIC part (a ty-
pical 14 pin SOIC weighs 0.1g, the Recom
SMD DC-DC converter weighs 1.5 ~ 2,7g).
It is advisable to consult your machine supplier
on the best choice of vacuum nozzle if in
doubt.
If placing these components by hand, handle
the components only by the central body area
where there are no component pins.
Component Alignment
The components can be aligned by either
optical recognition or manual alignment. If
using manual alignment it should be ensured
that the tweezers press on the component
body and not on the pins. The components
themselves are symmetrical along their axis,
hence relatively easy to align using either
method.
Solder Pad Design
The Recom SMD DC-DC converters are
designed on a pin pitch of 2,54mm (0.1") with
1,20 mm pad widths and 1,80 mm pad
lengths.
This allows pads from one part to be used
within a PCB CAD package for forming the pad
layouts for other SMD converters. These pads
are wider than many standard SOIC pad sizes
(0.64mm) and CAD packages may not
accommodate these pins with a standard SOIC
pad pattern. It should be remembered that
these components are power supply devices
and as such need broader pads and thicker
component leads to minimise resistive losses
within the interconnects.
160
140
120
100
80
60
Switching Frequency (kHz)
–20 020406080
100
Temperature (°C)
O/N
A/B
C/D
Under Full Load Conditions
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Top View
12.00
1.80
1.20
85
241
DC-DC Converter Applications
A-20 www.recom-electronic.com
2009
10-30s
(245°C)
min. 300s
Pre - Heat
Time (seconds)
300
250
200
150
100
50
50 100 150 300
250200 350 400 450 500
Temperature (°C)
Lead-free Recommended Soldering Profile (SMD parts)
3 - 5 seconds
Pre - Heat
Time (seconds)
120
Temperature (°C)
Lead-free Recommended Soldering Profile (Through hole parts)
Forced Cooling
60°C/s Min.
Natural Cooling
Enter Wave
Double Wave
100°C ~ 150°C Max.
110
100
90
8070
6050
40
30
20
10
0
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
Notes: 1. The wave solder profile is measured on lead temperature.
2. Need to keep the solder parts internal temperature less than about 210°C
Solder Reflow Profile
RECOM’s SMD converters are designed to
withstand a maximum reflow temperature of
245°C (for max. 30seconds) in accordance
with JEDEC STD-020C. If multiple reflow
profiles are to be used (i.e. the part is to
passthrough several reflow ovens), it is
recommended that lower ramp rates be used
than the maximum specified in JEDEC STD-
020C. Continual thermal cycling to this
profile could cause material fatigue, if more
than 5 maximum ramp cycles are used.
In general these parts will exceed the re-flow
capability of most IC and passive components
on a PCB and should prove the most thermally
insensitive component to the reflow conditions
Recommended Solder Reflow Profile:
The following 2 graphs show the typical
recommended solder reflow profiles for SMD
and through-hole ROHS compliant converters.
The exact values of the profile’s peak and its
maximum allowed duration is also given in the
datasheet of each converter.
Adhesive Requirements
If SM surface mount components are going to
be wave soldered (i.e. in a mixed through hole
and SMD PCB) or are to be mounted on both
sides of a PCB, then it is necessary to use an
adhesive to fix them to the board prior to
reflow.
The adhesive prevents the SMD parts being
”washed off“ in a wave solder, and being
”vibrated off“ due to handling on a double
sided SMD board.
As mentioned previously, the Recom range of
SMD DC-DC converters are heavier than
standard SOIC devices. The heavier weight is a
due to their size (volume) and internal hybrid
construction. Consequently the parts place a
larger than usual stress on their solder joints
and leads if these are the only method of
attachment. Using an adhesive between
component body and PCB can reduce this
stress considerably. If the final system is to be
subjected to shock and vibration testing, then
using adhesive attachment is essential to
ensure the parts pass these environmental
tests.
The Recom SMD DC-DC converters all have a
stand-off beneath the component for the
application of adhesive to be placed, without
interfering with the siting of the component.
The method of adhesive dispensing and cu-
ring, plus requirements for environmental test
and in-service replacement will determine sui-
tability of adhesives rather than the component
itself. However, having a thermoset plastic
body, thermoset epoxy adhesive bonding bet-
ween board and component is the recommen-
ded adhesive chemistry.
If the reflow stage is also to be used as a cure
for a heat cure adhesive, then the component
is likely to undergo high horizontal acceleration
and deceleration during the pick and place
operation. The adhesive must be sufficiently
strong in its uncured (green) state, in order to
keep the component accurately placed.
Adhesive Placement
The parts are fully compatible with the 3 main
methods of adhesive dispensing; pin transfer,
printing and dispensing. The method of placing
adhesive will depend on the available processes
in the production line and the reason for using
adhesive attachment. For example, if the part
is on a mixed though-hole and SMD board,
adhesive will have to be placed and cured prior
to reflow. If using a SMD only board and heat
cure adhesive, the reflow may be used as the
cure stage. If requiring adhesive for shock
and vibration, but using a conformal coat, then
it may be possible to avoid a separate
adhesive alltogether, and the coating alone
provides the mechanical restraint on the
component body.
www.recom-international.com A-21
2009
DC-DC Converter Applications
Patterns for dispensing or printing adhesive are
given for automatic lines. If dispensing
manually after placement the patterns for UV
cure are easily repeated using a manual
syringe (even if using heat cure adhesive).If dis-
pensing manually, dot height and size are not
as important, and the ad-hesive should be
applied after the components have been
reflowed. When dispensing after reflow, a chip
underfill formulation adhesive would be the
preferred choice. These types 'wick' under the
component body and offer a good all round
adhesion from a single dispensed dot.
The patterns allow for the process spread of
the stand-off on the component, but do not
account for the thickness of the PCB tracks.
If thick PCB tracks are to be used, a grounded
copper strip should be laid beneath the centre
of the component (care should be exercised to
maintain isolation barrier limits). The adhesive
should not retard the pins reaching their solder
pads during placement of the part, hence low
viscosity adhesive is recommended.
The height of the adhesive dot, its viscosity and
slumping properties are critical. The dot must
be high enough to bridge the gap between
board surface and component, but low enough
not to slump and spread, or be squeezed by
the component, and so contaminate the solder
pads.
If wishing to use a greater number of dots of
smaller diameter (common for pin transfer
methods), the dot pattern can be changed, by
following a few simple guidelines. As the
number of dots is doubled their diameter
should be halved and centres should be at
least twice the printed diameter from each
other, but the dot height should remain at
0.4mm. The printed dot should always be
positioned by at least its diameter from the
nearest edge of the body to the edge of the
dot. The number of dots is not important,
provided good contact between adhesive and
body can be guaranteed, but a minimum of two
dots is recommended.
Cleaning
The thermoset plastic encapsulating material
used for the Recom range of surface mount
DC-DC converters is not fully hermetically
sealed. As with all plastic encapsulated active
devices, strongly reactive agents in hostile
environments can attack the material and the
internal parts, hence cleaning is recommended
in inert solutions (e.g. alcohol or water based
solvents) and at room temperature in an inert
atmospheres (e.g. air or nitrogen).
A batch or linear aqueous cleaning process
would be the preferred method of cleaning
using a deionised water solution.
Vapour Phase Reflow Soldering
Vapour phase soldering is a still upcoming
soldering practice; therefore there are no
standard temperature profiles available.
Principally, the Lead-free Soldering Profile
recommended by RECOM can be used for
vapour phase soldering. RECOM has tested
large quantities of 8-pin and 10-pin SMD
converters and recommends as an absolute
maximum condition 240°C for 90s dwell time.
In standard applications with small sized
components on a pcb, 230°C and shorter
dwell times will still deliver good results.
After discussions with various contract
manufacturers, we recommended that the
temperature gradients used during preheat and
cooling phases are between 0.5°K/s up to
3°K/s.
Other form factors than 8-pin or 10-pin SMD-
packages have not been fully tested under
vapour phase conditions. Please contact
RECOM in this case.
Custom DC-DC Converters
In addition to the standard ranges shown in this
data book, Recom have the capability to
produce custom DC-DC converters designed
to your specific requirements. In general, the
parts can be rapidly designed using computer
based CAD tools to meet any input or output
voltage requirements within the ranges of
Recom standard products (i.e. up to 48V at
either input or output). Prototype samples can
also be produced in short timescales.
Custom parts can be designed to your
specification, or where the part fits within a
standard series, the generic series specifica-
tion can be used. All custom parts receive the
same stringent testing, inspection and quality
procedures, as standard products. However
there is a minimum order quantity as the
additional documentation and administrative
tasks must be covered in terms of costs.
A general figure for this MOQ can be around
3000pcs of low wattage converters
(0,25W ~ 2W), 1000pcs medium sized
wattage (2W~15W) and 500pcs for higher
wattages (> 20W).
Recom custom parts are used in many
applications, which are very specific to the
individual customer, however, some typical
examples are:
●ECL Logic driver
●Multiple cell battery configurations
●Telecommunications line equipment
●Marine apparatus
●Automotive electronics
●LCD display power circuitry
●Board level instrumentation systems
To discuss your custom DC-DC converter
requirements, please contact Recom technical
support desk or your local distributor.
Tin Whisker Mitigation
The use of pure tin coating has caused
considerable customer concern about the pos-
sibility of tin whisker formation. Although it is
the opinion of Recom that the risks of con-
verter failure due to tin whisker formation are
vanishingly small (the only actual recorded fai-
lures due to tin whiskers were in exceptional
environments such as deep space or as a
contributary factor to corona discharge
flashover in a UHV transformer), we have
undertaken tin whisker mitigation procedures
as recommended by Jedec in their JP002
guidelines.
Through Hole Devices:
The pins used in all of our through-hole
converters are made of hard silver-copper
alloy. The pins are then nickel underplated to
0.5µm before being pure tin electroplated to
6µm thickness. This thickness of overplating is
a compromise between reasonable
manufacturing costs and having a thick
enough coating to impair tin whisker formation.
The surface is not ‘brightened’, also to
mitigate tin whisker formation.
Finally the pins are annealed according to JIS
C3101. This reduces any residual forming
stresses, which is one of the other potential
causes of tin whisker formation
Surface Mount Devices:
The carrier frames used in our SMD converters
are made from DF42N nickel alloy which is
pure tin plated. The pins are hot dipped in
Sn-Ag-Cu solder just before injection molding.
Hot dipping with SnAg4 or SnAgCu is generally
an effective mitigation practice and considered
whisker free.
A-22 www.recom-electronic.com
2009
Innoline Application Notes
EMC Considerations
Although all Innoline converters are switching regulators, and contain internal high frequency oscillators, they have been designed to minimise
radiated and conducted emissions.
If the end-application is particularly sensitive to conducted interference, the following input filter can be used for all R-78, R-5xxx, R-6xxx and
R-7xxx converters.
10µF10µF
Input
Vin
GND
Vout
Output
50µH
50µH
Output Soft Start
Innoline converters with Vadj pins (R-78Axx-xxSMD, R-5xxx, R-6xxx and R-7xxx families) can be fitted with an external circuit to create an output
soft start. Any general purpose PNP transistor and diode can be used for TR1 and D1 and typical values for R1 = 100K and C1 = 10µF.
Vcc
GND
On/Off
+Vin +Vout
GND Vadj
Ctrl R1
C1
D1
TR1
Innoline Application Notes
●EMC Considerations
●Soft Start Circuit
●Positive-to-Negative Converters
R-78xx-0.5 Series
R-78Axx-0.5SMD Series
R-78xx-1.0 Series
R-78Axx-1.0SMD Series
R-78Bxx-1.0 Series
R-78HBxx-xx Series
R-62xxP_D Series
Pos-to-Neg Circuit Ideas
Contents
www.recom-international.com A-23
2009
Series Maximum Input Voltages Output Voltages No. of Case Adjustable Max
Output (VDC) (VDC) Outputs Vout? Cap.
Current min. max. Load
R-78xx-0.5 -0.4A 4.75 – 28, -1.5, -1.8, -2.5, -3.3, -5.0, S SIP3 No 220µF
-0.2A 5.0 – 26, 8.0 – 18 -6.5, -9.0, -12, -15
R-78Axx-0.5SMD -0.4A 4.75 – 28, -1.5, -1.8, -2.5, -3.3, -5.0, S SMD Yes 220µF
-0.2A 5.0 – 26, 8.0 – 18 -6.5, -9.0, -12, -15
R-78xx-1.0 Not recommended to be used in this mode due to the reduced input and output voltage range
R-78Axx-1.0SMD Not recommended to be used in this mode due to the reduced input and output voltage range
R-78Bxx-1.0 -0.6A 4.75 – 28, -1.5, -1.8, -2.5, -3.3, -5.0, S SIP3 No 220µF
-0.4A 8.0 – 28, 8.0 – 26 -6.5, -9.0,
-0.3A 8.0 – 18 -12, -15
R-78Bxx-1.5 Not recommended to be used in this mode due to the reduced input and output voltage range
R-78HBxx-0.5 -0.4A/-0.35A 15 – 65, -3.3, -5.0,-6.5 S SIP3 No 100µF
-0.3A/-0.25A/-0.2A 15 – 62, 15 – 59, 15 – 56, -9.0, -12, -15
-0.2A 20 – 48 -24
R-5xxxP/DA Not recommended to be used in this mode due to the reduced input and output voltage range
R-61xxP/D Not recommended to be used in this mode as R-78B series offer a lower cost alternative
R-62xxP/D -1A/-0.8A/-0.6A 9 - 28, 9-26 -1.8, -2.5, -3.3, -5, -9, -12 S SIP12 Yes 470µF
R-7xxxP/D Not recommended to be used in this mode due to the reduced efficiency and higher Ripple & Noise figures.
Circuit Ideas
●●Innoline Switching Regulators can also be used
to convert a positive voltage into a negative
voltage
●●TThhee ssttaannddaarrdd ppaarrttss ccaann bbee uusseedd -- oonnllyy ttwwoo eexxttrraa
ccaappaacciittoorrss aarree rreeqquuiirreedd
●●Fixed and variable output voltages are available.
●●Input voltage range can be lower than the output
voltage for higher output voltages
Positive-to-Negative Switching Regulators Selection Guide
Positive to Negative Converters
Innoline Application Notes
Features
Innoline
Innoline
Switching
Switching
Regulators
Regulators
A-24 www.recom-electronic.com
2009
INNOLINE
DC/DC-Converter
R-78xx-0.5
Series
Positive to
Negative
Converter
Selection Guide
Part Input Output Output Efficiency External Capacitors
Number Range (1) Voltage Current Min. Vin Max. Vin C1 C2*
SIP3 (V) (V) (A) (%) (%)
R-781.5-0.5 4.75 – 28 -1.5 -0.4 68 67 10µF/35V 22µF/6.3V
R-781.8-0.5 4.75 – 28 -1.8 -0.4 71 70 10µF/50V 22µF/6.3V
R-782.5-0.5 4.75 – 28 -2.5 -0.4 75 76 10µF/50V 22µF/6.3V
R-783.3-0.5 4.75 – 28 -3.3 -0.4 77 80 10µF/50V 22µF/6.3V
R-785.0-0.5 4.75 – 28 -5.0 -0.4 79 84 10µF/50V 22µF/10V
R-786.5-0.5 5.0 – 26 -6.5 -0.3 81 86 10µF/50V 10µF/10V
R-789.0-0.5 8.0 – 18 -9.0 -0.2 87 89 10µF/50V 10µF/16V
R-7812-0.5 8.0 – 18 -12 -0.2 87 90 10µF/50V 10µF/25V
R-7815-0.5 8.0 – 18 -15 -0.2 87 91 10µF/50V 10µF/25V
* Maximum capacitive load including C2 is 220µF
Output Power (%)
120
100
20
60
100750
-40
Operating Temperature (°C)
0
80
5025
71
Safe Operating Area
85
40
Derating-Graph
(Ambient Temperature)
Application Example (see also Circuit Ideas at end of section)
Positive to Negative Converter
+Vin R-78xx-0.5
-Vout
C1 C2
0V
0V
1
2
3
213
RECOM
R-785.0-05
****
Pin Connections
Pin # Negative Positive
Output Output
1 +Vin +Vin
2 -Vout GND
3 GND +Vout
C1 and C2 are required
and should be fitted close
to the converter pins.
Maximum capacitive load
including C2 is 220µF
R-78xx-0.5
-Vout
C1 C2
0V
0V
1
2
3
+Vin R-78xx-0.5
1
2
3+Vout
Maximum capacitive
load ±220µF
www.recom-international.com A-25
2009
INNOLINE
DC/DC-Converter
R-78A(A)
xx-0.5 SMD
Positive to
Negative
Converter
Selection Guide
Part Input Output Output Efficiency External Capacitors
Number Range (1) Voltage Current Min. Vin Max. Vin C1 C2
SIP3 (V) (V) (A) (%) (%)
R-78A(A)1.5-0.5SMD 4.75 – 28 -1.5 -0.4 68 67 10µF/35V 22µF/6.3V
R-78A(A)1.8-0.5SMD 4.75 – 28 -1.8 -0.4 71 70 10µF/50V 22µF/6.3V
R-78A(A)2.5-0.5SMD 4.75 – 28 -2.5 -0.4 75 76 10µF/50V 22µF/6.3V
R-78A(A)3.3-0.5SMD 4.75 – 28 -3.3 -0.4 77 80 10µF/50V 22µF/6.3V
R-78A(A)5.0-0.5SMD 4.75 – 28 -5.0 -0.4 79 84 10µF/50V 22µF/10V
R-78A(A)6.5-0.5SMD 5.0 – 26 -6.5 -0.3 81 86 10µF/50V 10µF/10V
R-78A(A)9.0-0.5SMD 8.0 – 18 -9.0 -0.2 87 89 10µF/50V 10µF/16V
R-78A(A)12-0.5SMD 8.0 – 18 -12 -0.2 87 90 10µF/50V 10µF/25V
R-78A(A)15-0.5SMD 8.0 – 18 -15 -0.2 87 91 10µF/50V 10µF/25V
* Maximum capacitive load including C2 is 220µF
Output Power (%)
120
100
20
60
100750
-40
Operating Temperature (°C)
0
80
5025
71
Safe Operating Area
85
40
Derating-Graph
(Ambient Temperature)
Application Example (see also Circuit Ideas at end of section)
Positive to Negative Converter
R-78A(A)xx-
0.5SMD
-Vout
+Vin
0V
1,2
10 3,7
8,9
6
4,5
R1
R2
On/Off
(Referenced to
-Vout)
C1
0V
C2
10 7
245
RECOM
R-78Axx-0.5SMD
xxxx
13
6
89
Pin Connections
Pin # Negative Positive
Output Output
1,2 +Vin +Vin
3,7,8,9 -Vout GND
4,5 GND +Vout
6 -Vout Adj. +Vout Adj.
10 On/Off On/Off
C1 and C2 are required
and should be fitted close
to the converter pins.
Maximum capacitive load
including C2 is 220µF
-Vout
0V
1,2
10 3,7
8,9
6
4,5
R1
R2
C1
0V
C2
R-78A(A)xx-
0.5SMD
+Vin 1,2
10 3,7
8,9
6
4,5
R1
R2
+Vout
On/Off
Opto-
coupler
Opto-
coupler
R-78A(A)xx-
0.5SMD
Maximum capacitive
load ±220µF
A-26 www.recom-electronic.com
2009
-Vout
-
1,2
10 3,7
8,9
6
4,5
10µF
0V
22µF
R-78A(A)12-
0.5SMD
Vin=15VDC
1,2
10 3,7
8,9
6
4,5 +Vout
+5V
+9V
+12V
+7.5V
26k
100k
200k
-5V
-9V
-12V
-7.5V
26k
100k
200k
Dual Rail Selectable Output Voltage Power Supply
+
R-78A(A)12-
0.5SMD
Typical Application
Table 1: Adjustment Resistor Values
INNOLINE
DC/DC-Converter R-78A(A)xx-0.5 SMD
Positive to Negative
0.5Adc R-78A(A)1.8 R-78A(A)2.5 R-78A(A)3.3 R-78A(A)5.0 R-78A(A)6.5 R-78A(A)9.0 R-78A(A)12
-0.5SMD -0.5SMD -0.5SMD -0.5SMD -0.5SMD -0.5SMD -0.5SMD
Vout (nom.) 1.8Vdc 2.5Vdc 3.3Vdc 5.0Vdc 6.5Vdc 9.0Vdc 12.0Vdc
VVoouutt ((aaddjj))RR11RR22RR11RR22RR11RR22RR11RR22RR11RR22 RR11RR22RR11RR22
-1.5 (V) 3KΩ200Ω
-1.8 (V) 12KΩ
-2.5 (V) 11.8KΩ
-3.0 (V) 4.64KΩ44.2KΩ88.4KΩ17KΩ
-3.3 (V) 27KΩ6.7KΩ
-3.6 (V) 60.4KΩ42KΩ14KΩ
-3.9 (V) 28KΩ58KΩ23KΩ
-4.5 (V) 11.3kΩ180KΩ49KΩ26KΩ17KΩ
-4.9 (V) 7.15kΩ850KΩ77kΩ36KΩ24KΩ
-5.0 (V) 6.34kΩ86kΩ39KΩ26KΩ
-5.1 (V) 5.9kΩ231kΩ97KΩ42KΩ28KΩ
-5.5 (V) 3.9kΩ56.2kΩ160KΩ56KΩ36KΩ
-6.5 (V) 14kΩ112KΩ63KΩ
-8.0 (V) 2.32kΩ24.6KΩ400KΩ125KΩ
-9.0 (V) 10.7KΩ200KΩ
-10 (V) 4.75KΩ54.9KΩ345KΩ
-11 (V) 1.65KΩ16.5KΩ740KΩ
-12 (V) 3.6KΩ
-12.6 (V) 0Ω180KΩ
www.recom-international.com A-27
2009
INNOLINE
DC/DC-Converter
R-78Bxx-
1.0 Series
Positive to
Negative
Converter
Selection Guide
Part Input Output Output Efficiency External Capacitors
Number Range (1) Voltage Current Min. Vin Max. Vin C1 C2*
SIP3 (V) (V) (A) (%) (%)
R-78B1.5-1.0 4.75 – 28 -1.5 -0.6 70 68 10µF/50V 22µF/6.3V
R-78B1.8-1.0 4.75 – 28 -1.8 -0.6 72 72 10µF/50V 22µF/6.3V
R-78B2.5-1.0 4.75 – 28 -2.5 -0.6 75 77 10µF/50V 22µF/6.3V
R-78B3.3-1.0 4.75 – 28 -3.3 -0.6 77 80 10µF/50V 22µF/6.3V
R-78B5.0-1.0 6.5 – 28 -5.0 -0.6 83 85 10µF/50V 22µF/10V
R-78B6.5-1.0 8.0 – 26 -6.5 -0.4 84 87 10µF/50V 10µF/10V
R-78B9.0-1.0 8.0 – 18 -9.0 -0.4 88 89 10µF/25V 10µF/25V
R-78B12-1.0 8.0 – 18 -12 -0.3 89 90 10µF/25V 10µF/25V
R-78B15-1.0 8.0 – 18 -15 -0.3 89 91 10µF/25V 10µF/25V
* Maximum capacitive load including C2 is 220µF
Output Power (%)
120
100
20
60
100750
-40
Operating Temperature (°C)
0
80
5025
71
Safe Operating Area
85
40
Derating-Graph
(Ambient Temperature)
Application Example (see also Circuit Ideas at end of section)
Positive to Negative Converter
+Vin R-78Bxx-1.0
-Vout
C1 C2
0V
0V
1
2
3
213
RECOM
R-78B5.0-1.0
****
Pb
Pin Connections
Pin # Negative Positive
Output Output
1 +Vin +Vin
2 -Vout GND
3 GND +Vout
C1 and C2 are required
and should be fitted close
to the converter pins.
Maximum capacitive load
including C2 is 220µF
R-78Bxx-1.0
-Vout
C1 C2
0V
0V
1
2
3
+Vin R-78Bxx-1.0
1
2
3+Vout
Maximum capacitive
load ±220µF
A-28 www.recom-electronic.com
2009
INNOLINE
DC/DC-Converter
R-78HBxx-
0.5 Series
Positive to
Negative
Converter
Selection Guide
Part Input Output Output Efficiency External Capacitors
Number Range (1) Voltage Current Min. Vin Max. Vin C1 C2*
SIP3 (V) (V) (A) (%) (%)
R-78HB3.3-0.5 15 – 65 -3.3 -0.4 78 75 1µF/100V 22µF/6.3V
R-78HB5.0-0.5 15 – 65 -5.0 -0.4 82 80 1µF/100V 22µF/10V
R-78HB6.5-0.5 15 – 65 -6.5 -0.35 84 82 1µF/100V 22µF/10V
R-78HB9.0-0.5 15 – 62 -9.0 -0.3 87 85 1µF/100V 10µF/16V
R-78HB12-0.5 15 – 59 -12 -0.25 88 86 1µF/100V 10µF/25V
R-78HB15-0.5 15 – 56 -15 -0.2 89 87 1µF/100V 10µF/25V
R-78HB15-0.5 15 – 48 -24 -0.2 89 87 1µF/100V 10µF/35V
* Maximum capacitive load including C2 is 100µF
Output Power (%)
120
100
20
60
100750
-40
Operating Temperature (°C)
0
80
5025
71
Safe Operating Area
85
40
Derating-Graph
(Ambient Temperature)
Application Example (see also Circuit Ideas)
Positive to Negative Converter
+Vin
R-78HBxx-0.5
-Vout
C1 C2
0V
0V
1
2
3
213
RECOM
R-78HB5.0-0.5
****
Pb
Pin Connections
Pin # Negative Positive
Output Output
1 +Vin +Vin
2 -Vout GND
3 GND +Vout
C1 and C2 are required
and should be fitted close
to the converter pins.
Maximum capacitive load
including C2 is 100µF
R-78HBxx-0.5
-Vout
C1 C2
0V
0V
1
2
3
+Vin
R-78HBxx-0.5
1
2
3+Vout
Maximum capacitive
load ±100µF
www.recom-international.com A-29
2009
Derating
Ambient Temperature (°C)
90
60
20
40
1.510.5
Internal Power Dissipation (W)
0
80
85
0.7
Max output current calculation:
Internal power dissipation
(1W) = Io x Vo x (1-Efficiency)
Io = 1(W) / Vo x (1-Efficiency)
Example : R-625.0P
at Vin = +9VDC, Vout=-5.0V
Efficiency = 80% (see ”Selection Guide” table)
Io = 1W / 5V x (1-0.8) = -1000mA
at Vin = +9VDC, Vout=-8.0V (with trim)
Efficiency = 80% (see ”Selection Guide” table)
Io = 1W / 8V x (1-0.8) = -625mA
Selection Guide
Part Input Output Output Efficiency External Capacitors
Number Range (1) Voltage Current Min. Vin Max. Vin C1 C2*
SIP3 (V) (V) (A) (%) (%)
R-621.8P/D 9 – 28 -1.8 (-1.5~-3.6) -1.0 72 65 10µF/50V 100µF/6.3V
R-622.5P/D 9 – 28 -2.5 (-1.5~-4.5) -1.0 76 72 10µF/50V 100µF/6.3V
R-623.3P/D 9 – 28 -3.3 (-1.8~-6V) -1.0 79 76 10µF/50V 100µF/10V
R-625.0P/D 9 – 28 -5.0 (-1.8~-9V) -1.0 81 80 10µF/50V 100µF/10V
R-629.0P/D 9 – 26 -9.0 (-3.3~-15V) -0.8 84 85 10µF/50V 100µF/25V
R-6212P/D 9 – 26 -12 (-3.3~-15V) -0.6 86 88 10µF/50V 100µF/25V
* Maximum capacitive load including C2 is 220µF
Positive to Negative Converter
R-62xxP/D
-Vout
+Vin
0V
2,3,4
15,6
7,8
12
9,10,
11
R1
R2
On/Off
(Referenced to
-Vout)
C1
0V
C2
1 2 3 4 5 6 7 8 9 10 11 12
RECOM
R-6212P
INNOLINE
DC/DC-Converter
R-62xxP/D
SIP12
Positive to
Negative
Converter
Pin Connections
Pin # Negative Positive
Output Output
2,3,4 +Vin +Vin
5,6,7,8 -Vout GND
9,10,11 GND +Vout
12 -Vout Adj. +Vout Adj.
1 On/Off On/Off
C1 and C2 are required
and should be fitted close
to the converter pins.
Maximum capacitive load
including C2 is 220µF
A-30 www.recom-electronic.com
2009
Remote On/Off Control Application Example
INNOLINE
DC/DC-Converter
Table 1: Adjustment Resistor Values
-1Adc R-621.8P/D R-622.5P/D R-623.3P/D R-625.0P/D
Vout (nominal) 1.8VDC 2.5VDC 3.3VDC 5VDC
Vout (adj) R1 R2 R1 R2 R1 R2 R1 R2
1.5 13.6KΩ3.3KΩ
1.8 8.2KΩ3.1KΩ820Ω
2.0 10KΩ15KΩ5.1KΩ1.5KΩ
2.5 5.1KΩ13KΩ3.6KΩ
3.0 2.5KΩ10KΩ51KΩ7.0KΩ
3.3 1.7KΩ5.9KΩ9.7KΩ
3.6 1.2KΩ3.9KΩ18KΩ14KΩ
3.9 2.8KΩ9.1KΩ20KΩ
4.5 1.6KΩ3.9KΩ60KΩ
5.0 2.4KΩ
5.1 2.2KΩ60KΩ
5.5 1.6KΩ15KΩ
6.0 1.1KΩ7.2KΩ
7.0 2.8KΩ
8.0 1.5KΩ
-Vout
0V
R1
R2
C1
0V
C2
R-6xxxP
+Vin 2,3,4
15,6
7,8
12
9,10,11
R1
R2
+Vout
On/Off
Opto-
coupler
Opto-
coupler
R-62xxP
100µF
2,3,4
15,6
7,8
12
9,10,
11
Maximum capacitive
load ±220µF
R-62xxP_D
Positive to Negative
www.recom-international.com A-31
2009
Positive to Negative
Circuit Ideas
Application Examples
INNOLINE
DC/DC-Converter
-12V
R-78B12-1.0
-24V @ 300mA
10µF/
25V
10µF/
25V
0V
1
2
3
0V
+Ve R-7812-0.5
0V
10µF/
25V
10µF/
25V
-Ve
1
2
3
12V
Vbatt =
8~18V
L
R-7805-0.5
-5V @ -400mA
10µF/
25V
22µF/
10V
N
1
2
3
+12V @ 655mA
RAC10-
12SB 0V
60mm
27.2mm
C4
C2
Ultra-compact low noise
regulated and protected
AC/DC dual output supply.
47µF/
16V
C3
0.1µF
C1
C1
C2
C3 C4
RAC10 AC/DC Converter R-78
Negative Voltage Doubler
12V Battery Stabilisor
Negative Rail Generator for Asymmetric Rails
A-32 www.recom-electronic.com
2009
Common Mode Chokes for EMC
Recom offers a range of Common Mode Chokes useful for EMI Filtering to meet the requirements of EN-55022, Class B.
The component values given are suggested values and may need to be optimised to suit the application. The effectiveness of any filter
network is heavily dependent on using quality capacitors, the layout of the board and having a low impedance path to ground.
See section on filtering elsewhere in the Application Notes for more details.
++
C2
Output
C1
Input
CMC
C3
C4
100nF
(fit close
to pins)
Class B EMC Filter Suggestion
Powerline Application Notes
Powerline DC/DC Application
Notes
●Common Mode Chokes for EMC
●Powerline Definitions and Testing
Introduction
Input Voltage Range
Pi Filter
Output Voltage Accuracy
Voltage Balance
Line Regulation
Load Regulation
Efficiency
Switching Frequency
Output Ripple and Noise
Transient Recovery Time
Current Limiting
Fold Back Current Limiting
Isolation
Break Down Voltage
Temperature Coefficient
Ambient Temperature
Operating Temperature Range
Storage Temperature Range
●Undervoltage Lockout Tables
●Output Voltage Trim Tables
●Powerline Heat Sinks
Heat Sink Dimensions
Powerline AC/DC Application
Notes
Input Fuse
Earthing
Combining Converters
DC Inputs
Contents
Standard EMC Filter
www.recom-international.com A-33
2009
Powerline DC-DC Application Notes
RP15-SO_DO and RP15-SOW_DOW Series Only
+++
C2
Output
C1
Input
CMC
470pF/ 3kV
470pF/ 3kV
C3
RP15-SO_DO
Vout+
Vout-
L1
RP30-SF_DF and RP30-SF W_DFW Series Only
+++
C2
Trim or
Common
C1
Input
CMC-09
C5
C4
C3
RP30-SF_DF
RP30-SFW_DFW
Vout+
Vout-
CMC-10
C6
A-34 www.recom-electronic.com
2009
Component Values
All capacitors MLCC (Multi Layer Ceramic Capacitor).
RP08-A Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/3kV, CMC-06
Vin = 24VDC nom., C1=6.8µF/50V, C2=Not Required, C3,C4=1nF/3kV, CMC-06
Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/3kV, CMC-06
RP08-AW Vin = 9~36VDC, C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/3kV, CMC-06
Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/3kV, CMC-06
RP10-E Vin = 12VDC nom., C1=3.3µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06
RP12-A Vin = 24VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06
Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06
RP10-EW Vin = 9~36VDC, C1=3.3µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06
RP12-AW Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-07
RP15-A Vin = 12VDC nom., C1=10µF/25V, C2=10µF/25V, C3,C4=470pF/2kV, CMC-07
Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=470pF/2kV, CMC-06
Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=470pF/2kV, CMC-01
RP15-AW Vin = 9~36VDC, C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=470pF/2kV, CMC-05
Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=470pF/2kV, CMC-06
RP15-O Vin = 12VDC nom., C1=10µF/25V, C2=10µF/25V, L1 = 10µH, , CMC-07
Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, L1 = 10µH, , CMC-07
Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, L1 = 18µH, CMC-07
RP15-OW Vin = 9~36VDC, C1, C2, C3 =6.8µF/50V, CMC-07
Vin = 18~75VDC, C1=2 x 2.2µF/100V in parallel, C2,C3 =2.2µF/100V, L1 = 33µH, CMC-06
RP15-F Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06
Vin = 24VDC nom., C1=3.3µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06
Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06
RP15-FW Vin = 9~36VDC, C1=2.2µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05
Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06
RP20-F Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05
Vin = 24VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05
Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-05
RP20-FW Vin = 9~36VDC, C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05
Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06
RP30-E Vin = 12VDC nom., C1=4.7µF/25V, C2=Not Required, C3,C4=1nF/2kV, CMC-05
Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=1nF/2kV, CMC-05
Vin = 48VDC nom., C1=2.2µFII2.2µF/100V, C2=2.2µFII2.2µF/100V, C3,C4=1nF/2kV, CMC-05
RP30-EW Vin = 9~36VDC, C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=1nF/2kV, CMC-05
Vin = 18~75VDC, C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV, CMC-05
Continued on next page
Powerline DC-DC Application Notes
www.recom-international.com A-35
2009
Powerline DC-DC Application Notes
RP30-F Vin = 12VDC nom., C1, C2, C3 =10µF/25V, C4, C5, C6=1nF/2kV, CMC1 = CMC-09, CMC2 = CMC-10
Vin = 24VDC nom., C1, C2, C3 =4.7µF/50V, C4, C5, C6=1nF/2kV, CMC1 = CMC-09, CMC2 = CMC-10
Vin = 48VDC nom., C1, C2, C3 =2.2µF/100V, C4, C5, C6=1nF/2kV, CMC1 = CMC-09, CMC2 = CMC-10
RP30-FW Vin = 9~36VDC, C1, C2, C3 =4.7µF/50V, C4, C5, C6=1nF/2kV, CMC1 = CMC-09, CMC2 = CMC-10
Vin = 18~75VDC, C1, C2, C3 =4.7µF/50V, C4, C5, C6=1nF/2kV, CMC1 = CMC-09, CMC2 = CMC-10
RP40-G Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05
Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=1nF/2kV, CMC-05
Vin = 48VDC nom., C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV, CMC-08
RP40-GW Vin = 9~36VDC, C1=4.7µF/50V, C2=4.7µF/50V, C3,C4=1nF/2kV, CMC-05
Vin = 18~75VDC, C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV, CMC-08
RP60-G Vin = 24VDC nom., C1=4.7µF/50V, C2=4.7µF/50V, C3,C4=1nF/2kV, CMC-05
Vin = 48VDC nom., C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV,CMC-08
2
1
43
C1 C2
C3
C4
CMC
100
nF
Recommended PCB Layouts
Standard EMC Filter
RP15-O Open Frame
Converters
2
1
43
C1 C2 C3
L1
CMC
470
pF
470
pF
A-36 www.recom-electronic.com
2009
CMC-01
Component Inductance Rating DCR
CMC-01 620µHx2 1.7A 80mOhm
2.54 2
1
43
2.54 Top View
43
12
j 0.6 ± 0.1
7.62 ± 0.2
9.5 ± 0.1
9.5 ± 0.1
7.8 max.
2.5 min.
7.5 ± 0.2
Recommended Footprint Details
Powerline DC-DC Application Notes
2
1
43
C1 C2 C3
CMC-09
2
1
43
C4
C5
C6
CMC-10
Recommended PCB Layouts
RP30-S_DF
RP30-S_DFW
General Information about Recom Common Mode Chokes
Recom common mode chokes are all RoHS conform.
Maximum Rated Voltage = 500VDC
Operating Temperature = -40°C ~ +105°C
Typical Impedance curve (CMC-08)
www.recom-international.com A-37
2009
43
12
j 0.6 ± 0.1
7.5 ± 0.2
11.0 max
11.0 max
9.8 max.
2.5 min.
7.62 ± 0.2
43
12
j 0.6 ± 0.1
7.5 ± 0.2
11.0 max
11.0 max
8.8 max.
2.5 min.
7.62 ± 0.2
Powerline DC-DC Application Notes
CMC-05
Component Inductance Rating DCR
CMC-05 450µHx2 5.2A 25mOhm
CMC-06
Component Inductance Rating DCR
CMC-06 325µHx2 3.3A 35mOhm
43
12
j 0.6 ± 0.1
7.5 ± 0.2
11.0 max
11.0 max
8.8 max.
2.5 min.
7.62 ± 0.2
43
12
j 0.6 ± 0.1
7.5 ± 0.2
11.0 max
11.0 max
9.8 max.
2.5 min.
7.62 ± 0.2
CMC-07
Component Inductance Rating DCR
CMC-7 145µHx2 5.2A 20mOhm
CMC-08
Component Inductance Rating DCR
CMC-8 830µHx2 5.2A 31mOhm
43
12
j 0.6 ± 0.1
7.5 ± 0.2
11.0 max
11.0 max
8.8 max.
2.5 min.
7.62 ± 0.2
43
12
j 0.6 ± 0.1
7.5 ± 0.2
11.0 max
11.0 max
8.8 max.
2.5 min.
7.62 ± 0.2
CMC-09
Component Inductance Rating DCR
CMC-7 33,3µHx2 3.3A 10mOhm
CMC-10
Component Inductance Rating DCR
CMC-10 55µHx2 4A 7mOhm
A-38 www.recom-electronic.com
2009
Definitions and Testing
AA
VV
DC Power
Source
DC/DC
Converter
under Test
+V
-V
( VDC or VRMS ) Adjustable
load
General Test Set-Up
Note: If the converter is under test with
remote sense pins, connect these pins
to their respective output pins. All tests
are made in ”Local sensing“ mode.
FFiigguurree 11--33:: GGeenneerraall DDCC//DDCC ccoonnvveerrtteerr tteesstt sseett--uupp
Make and record the following measure-
ments with rated output load at +25°C:
●Output voltage at nominal line
(input) voltage. Vout N
●Output voltage at high line (input)
voltage. Vout H
●Output voltage at low line (input)
voltage. Vout L
The line regulation is Vout M (the maxi-
mum of the two deviations of output) for
the value at nominal input in percentage.
Vout M – Vout N
Vout NX100
Line Regulations
The minimum and maximum input vol-
tage limits within which a converter
will operate to specifications.
An input filter, consisting of two capacitors,
connected before and after a series
inductor to reduce input reflected ripple
current. The effective filter is C1/L
+ L/C2, so the inductor filter element is
doubly effective.
Input Voltage Range
PI Filter
Output Voltage Accuracy
L
C2 Output
C1
Input
Figure 2: PI Filter
With nominal input voltage and rated
output load from the test set-up, the DC
output voltage is measured with an
accurate, calibrated DC voltmeter.
Output voltage accuracy is the difference
between the measured output voltage
and specified nominal value as a
percentage. Output accuracy (as a %) is
then derived by the formula:
Vnom is the nominal output specified in
the converter data sheet.
Vout – Vnom
Vnom NX100
For a multiple output power converter,
the percentage difference in the voltage
level of two outputs with opposite polar-
rities and equal nominal values.
Voltage Balance
Powerline DC-DC Application Notes
www.recom-international.com A-39
2009
Definitions and Testing
Make and record the following measure-
ments with rated output load at +25°C:
●Output voltage with rated load
connected to the output. (Vout FL)
●●OOuuttppuutt vvoollttaaggee wwiitthh nnoo llooaadd oorr tthhee
mmiinniimmuumm ssppeecciiffiieedd llooaadd ffoorr tthhee
DDCC--DDCC ccoonnvveerrtteerr.. ((VVoouutt MMLL))
Load regulation is the difference between
the two measured output voltages as a
percentage of output voltage at rated
load.
The rate at which the DC voltage is swit-
ched in a DC-DC converter or switching
power supply. The ripple frequency is
double the switching frequency in push-
pull designs.
Because of the high frequency content
of the ripple, special measurement tech-
niques must be employed so that correct
measurements are obtained. A 20MHz
bandwidth oscilloscope is used, so that
all significant harmonics of the ripple
spike are included.
This noise pickup is eliminated as shown
in Figure 3, by using a scope probe with
an external connection ground or ring
and pressing this directly against the
output common terminal of the power
converter, while the tip contacts the vol-
tage output terminal. This provides the
shortest possible connection across the
output terminals.
The ratio of output load power consump-
tion to input power consumption expres-
sed as a percentage. Normally measured
at full rated output power and nominal
line conditions.
Ground Ring
to Scope
+
Output
-
Vout ML – Vout FL
Vout FL X100
Figure 3:
Load Regulation
Efficiency
Switching Frequency
Output Ripple and Noise
Powerline DC-DC Application Notes
A-40 www.recom-electronic.com
2009
Figure 4 shows a complex ripple voltage
waveform that may be present on the
output of a switching power supply.
There are three components in the wa-
veform, first is a charging component that
originates from the output rectifier and
filter, then there is the discharging com-
ponent due to the load discharging the
output capacitor between cycles, and
finally there are small high frequency
switching spikes imposed on the low
frequency ripple.
Peak-Peak
Amplitude
Time
Figure 4: Amplitude
Output Ripple and Noise (continued)
Transient Recovery Time
Current Limiting
Fold Back Current Limiting
The time required for the power supply
output voltage to return to within a speci-
fied percentage of rated value, following
a step change in load current.
output current is limited to prevent
damage of the converter at overload
situations. If the output is shorted, the
output voltage is regulated down so the
current from the outputs cannot be
excessive.
A method of protecting a power supply
from damage in an overload condition,
reducing the output current as the load
approaches short circuit.
Rated Io
V out
I out
Figure 6: Fold Back Current LimitingTime
Load
Undershoot
Overshoot
V out
I out
Time
Transient
Recovery Time
Output
Voltage
5V + U
5V
5V - L
U: upper limit
L: lower limit
Figure: 5 Transient Recovery Time
Definitions and Testing
Powerline DC-DC Application Notes
www.recom-international.com A-41
2009
The electrical separation between the
input and output of a converter, (consis-
ting of resistive and capacitive isolation)
normally determined by transformer-
characteristics and circuit spacing.
The maximum continuous DC voltage,
which may be applied between the input
and output terminal of a power supply
without causing damage.
Typical break-down voltage for DC-DC
converters is 1600VDC because the
equivalent DC isolation for 230VAC
continuous rated working voltage is
1500VDC.
With the power converter in a tempera-
ture test chamber at full rated output
load, make the following measurements:
●●OOuuttppuutt vvoollttaaggee aatt ++2255°°CC aammbbiieenntt
tteemmppeerraattuurree..
●●SSeett tthhee cchhaammbbeerr ffoorr mmaaxxiimmuumm
ooppeerraattiinngg aammbbiieenntt tteemmppeerraattuurree
aanndd aallllooww tthhee ppoowweerr ccoonnvveerrtteerr ttoo
ssttaabbiilli
izzee ffoorr 1155 ttoo 3300 mmiinnuutteess..
MMeeaassuurree tthhee oouuttppuutt vvoollttaaggee..
●●SSeett tthhee cchhaammbbeerr ttoo mmiinniimmuumm
ooppeerraattiinngg aammbbiieenntt tteemmppeerraattuurree aanndd
aallllooww tthhee ppoowweerr ccoonnvveerrtteerr ttoo
ssttaabbiilliiz
zee ffoorr 1155 ttoo 3300 mmiinnuutteess..
●●DDiivviiddee eeaacchh ppeerrcceennttaaggee vvoollttaaggee
ddeevviiaattiioonn ffrroomm tthhee ++2255°°CC aammbbiieenntt
vvaalluuee bbyy tthhee ccoorrrreessppoonnddiinngg tteemmppee--
rraattuurree cchhaannggee ffrroomm ++2255°°CC
aammbbiieenntt..
The temperature coefficient is the higher
one of the two values calculated above,
expressed as percent per change centi-
grade.
Output
Rectifier
and
Regulator
Input
Breakdown Voltage
Resistive and
Capacitive Isolation
C
R
Isolation
Break-Down Voltage
Temperature Coefficient
Ambient Temperature
Operating Temperature Range
Storage Temperature Range
Figure 7:
The temperature of the still-air im-
mediately surrouding an operating
power supply. Care should be taken
when comparing manufacturer’s data-
sheets that still-air ambient tempera-
ture and not case temperature is
quoted.
The range of ambient or case tempe-
rature within a power supply at which
it operates safely and meets its
specifications.
The range of ambient temperatures
within a power supply at non-opera-
ting condition, with no degradation in
its subsequent operation.
Definitions and Testing
Powerline DC-DC Application Notes
A-42 www.recom-electronic.com
2009
Some converters from our Powerline offer
the feature of trimming the output voltage in
a certain range around the nominal value
by using external trim resistors.
Because different series use different cir-
cuits for trimming, no general equation can
be given for calculating the trim resistors.
The following trimtables give values for
chosing these trimming resistors.
If voltages between the given trim points
are required, extrapolate between the two
nearest given values to work out the
resistor required or use a variable resistor
to set the voltage.
Output Voltage Trimming:
Trim up 12345678910%
Vout = 3,333 3,366 3,399 3,432 3,465 3,498 3,531 3,564 3,597 3,63 Volts
RU= 57.93 26.16 15.58 10.28 7.11 4.99 3.48 2.34 1.46 0.75 KOhms
Trim down 12345678910%
Vout = 3,267 3,234 3,201 3,168 3,135 3,102 3,069 3,036 3,003 2,97 Volts
RD= 69.47 31.23 18.49 12.12 8.29 5.74 3.92 2.56 1.50 0.65 KOhms
RP15-, RP20-, RP30-, RP40-, RP60- xx3.3S (For RP15-SA/SAW and RP15-SO/SOW see next page)
Trim up 12345678910%
Vout = 5,05 5,1 5,15 5,2 5,25 5,3 5,35 5,4 5,45 5,5 Volts
RU= 36.57 16.58 9.92 6.58 4.59 3.25 2.30 1.59 1.03 0.59 KOhms
Trim down 12345678910%
Vout = 4,95 4,9 4,85 4,8 4,75 4,7 4,65 4,6 4,55 4,5 Volts
RD= 45.53 20.61 12.31 8.15 5.66 4.00 2.81 1.92 1.23 0.68 KOhms
RP15-, RP20-, RP30-, RP40-, RP60- xx05S (For RP15-SA/SAW and RP15-SO/SOW see next page)
Trim up 12345678910%
Vout = 12,12 12,24 12,36 12,48 12,6 12,72 12,84 12,96 13,08 13,2 Volts
RU= 367.91 165.95 98.64 64.98 44.78 31.32 21.70 14.49 8.88 4.39 KOhms
Trim down 12345678910%
Vout = 11,88 11,76 11,64 11,52 11,4 11,28 11,16 11,04 10,92 10,8 Volts
RD= 460.99 207.95 123.60 81.42 56.12 39.25 27.20 18.16 11.13 5.51 KOhms
RP15-, RP20-, RP30-, RP40- ,RP60-xx12S (For RP15-SA/SAW and RP15-SO/SOW see next page)
Trim up 12345678910%
Vout = 15,15 15,3 15,45 15,6 15,75 15,9 16,05 16,2 16,35 16,5 Volts
RU= 404.18 180.59 106.06 68.80 46.44 31.53 20.88 12.90 6.69 1.72 KOhms
Trim down 12345678910%
Vout = 14,85 14,7 14,55 14,4 14,25 14,1 13,95 13,8 13,65 13,5 Volts
RD= 499.82 223.41 131.27 85.20 57.56 39.14 25.97 16.10 8.42 2.282 KOhms
RP15-, RP20-, RP30-, RP40-, RP60- xx15S (For RP15-SA/SAW and RP15-SO/SOW see next page)
Single Output Voltage Trim Tables
Trim Tables
Powerline DC-DC Application Notes
www.recom-international.com A-43
2009
Trim up 12345678910%
Vout = 3,333 3,366 3,399 3,432 3,465 3,498 3,531 3,564 3,597 3,63 Volts
RU= 385.07 191.51 126.99 94.73 75.37 62.47 53.25 46.34 40.96 36.66 KOhms
Trim down 12345678910%
Vout = 3,267 3,234 3,201 3,168 3,135 3,102 3,069 3,036 3,003 2,97 Volts
RD= 116.72 54.78 34.13 23.81 17.62 13.49 10.54 8.32 6.60 5.23 KOhms
RP15-xx3.3SA, RP15-xx3.3SAW, RP15-xx3.3SO, RP15-xx3.3SOW
Trim up 12345678910%
Vout = 5,05 5,1 5,15 5,2 5,25 5,3 5,35 5,4 5,45 5,5 Volts
RU= 253.45 125.70 83.12 61.82 49.05 40.53 34.45 29.89 26.34 23.50 KOhms
Trim down 12345678910%
Vout = 4,95 4,9 4,85 4,8 4,75 4,7 4,65 4,6 4,55 4,5 Volts
RD= 248.34 120.59 78.01 56.71 43.94 35.42 29.34 24.78 21.23 18.39 KOhms
RP15-xx05SA, RP15-xx05SAW, RP15-xx05SO, RP15-xx05SOW
Trim up 12345678910%
Vout = 12,12 12,24 12,36 12,48 12,6 12,72 12,84 12,96 13,08 13,2 Volts
RU= 203.22 99.06 64.33 46.97 36.56 29.61 24.65 20.93 18.04 15.72 KOhms
Trim down 12345678910%
Vout = 11,88 11,76 11,64 11,52 11,4 11,28 11,16 11,04 10,92 10,8 Volts
RD= 776.56 380.72 248.78 182.81 143.22 116.83 97.98 83.85 72.85 64.06 KOhms
RP15-xx12SA, RP15-xx12SAW, RP15-xx12SO, RP15-xx12SOW
Trim up 12345678910%
Vout = 15,15 15,3 15,45 15,6 15,75 15,9 16,05 16,2 16,35 16,5 Volts
RU= 161.56 78.22 50.45 36.56 28.22 22.67 18.70 15.72 13.41 11.56 KOhms
Trim down 12345678910%
Vout = 14,85 14,7 14,55 14,4 14,25 14,1 13,95 13,8 13,65 13,5 Volts
RD= 818.22 401.56 262.67 193.22 151.56 123.78 103.94 89.06 77.48 68.22 KOhms
RP15-xx15SA, RP15-xx15SAW, RP15-xx15SO, RP15-xx15SOW
RP15-S_DA, RP15 S:DAW Output Voltage Trim Tables
Trim Tables
Powerline DC-DC Application Notes
A-44 www.recom-electronic.com
2009
Trim up 12345678910%
Vout = 10,1 10,2 10,3 10,4 10,5 10,6 10,7 10,8 10,9 11 Volts
RU= 90.30 40.60 24.03 15.75 10.78 7.47 5.1 3.32 1.94 0.84 KOhms
Trim down 12345678910%
Vout = 9,9 9,8 9,7 9,6 9,5 9,4 9,3 9,2 9,1 9 Volts
RD= 109.3 49.00 28.90 18.85 12.82 8.80 5.93 3.77 2.10 0.76 KOhms
RP15-, RP20- xx05D
Trim up 12345678910%
Vout = 24,24 24,48 24,72 24,96 25,2 25,44 25,68 25,92 26,16 26,4 Volts
RU= 218.21 98.10 58.07 38.05 26.04 18.03 12.32 8.03 4.69 2.02 KOhms
Trim down 12345678910%
Vout = 23,76 23,52 23,28 23,04 22,8 22,56 22,32 22,08 21,84 21,6 Volts
RD= 273.44 123.02 72.87 47.80 32.76 22.73 15.57 10.20 6.02 2.67 KOhms
RP15-, RP20, RP30- xx12D
Trim up 12345678910%
Vout = 30,3 30,6 30,9 31,2 31,5 31,8 32,1 32,4 32,7 33 Volts
RU= 268.29 120.64 71.43 46.82 32.06 22.21 15.1 9.91 5.81 2.53 KOhms
Trim down 12345678910%
Vout = 29,7 29,4 29,1 28,8 28,5 28,2 27,9 27,6 27,3 27 Volts
RD= 337.71 152.02 90.13 59.18 40.61 28.23 19.39 12.76 7.60 3.47 KOhms
RP15-, RP20-, RP30-- xx15D
Dual Output Voltage Trim Tables
Trim Tables
Powerline DC-DC Application Notes
www.recom-international.com A-45
2009
Undervoltage Lockout Tables
At low input voltages, the input currents
can exceed the rating of the converter.
Therefore, converters featuring under-
voltage lockout will automitically shut
down if the input voltage is too low. As
the input voltage rises, they will restart.
Undervoltage Lockout
Converter Series Nominal Input Voltage Switch ON Switch OFF
input voltage input voltage
RP08-S_DAW 24V (9~36VDC) 9VDC 8VDC
48V (18~75VDC) 18VDC 16VDC
RP12-S_DA 12V (9~18VDC) 9VDC 8VDC
24V (18~36VDC) 18VDC 16VDC
48V (36~75VDC) 36VDC 33VDC
RP12-S_DAW 24V (9~36VDC) 9VDC 8VDC
48V (18~75VDC) 18VDC 16VDC
RP15-S_DA, RP15-S_DO 12V (9~18VDC) 9VDC 8VDC
24V (18~36VDC) 17VDC 14.5VDC
48V (36~75VDC) 33VDC 30.5VDC
RP15-S_DAW, RP15-S_DOW 24V (9~36VDC) 9VDC 8VDC
48V (18~75VDC) 18VDC 16VDC
RP15-S_DFW 24V (9~36VDC) 9VDC 7.5VDC
48V (18~75VDC) 18VDC 15VDC
RP20-S_DFW 24V (9~36VDC) 9VDC 7.5VDC
48V (18~75VDC) 18VDC 15VDC
RP30-S_DE 12V (9~18VDC) 9VDC 8VDC
24V (18~36VDC) 17.8VDC 16VDC
48V (36~75VDC) 36VDC 33VDC
RP30-S_DEW 24V (10~40VDC) 10VDC 8VDC
48V (18~75VDC) 18VDC 16VDC
RP40-S_D_TG 12V (9~18VDC) 9VDC 8VDC
24V (18~36VDC) 17.8VDC 16VDC
48V (36~75VDC) 36VDC 34VDC
RP30-S_DGW 24V (9~36VDC) 9VDC 8VDC
48V (18~75VDC) 18VDC 16VDC
RP60-SG 24V (18~36VDC) 17VDC 15VDC
48V (36~75VDC) 34VDC 32VDC
Undervoltage Lockout
Powerline DC-DC Application Notes
A-46 www.recom-electronic.com
2009
DC-DC Converter Applications
Thermal Management-
The Laws of Thermodynamics
Smaller, more powerful, better performance
…are the buzzwords in the area of DC/DC
module power supplies. Good thermal
management of the heat generated has
become an important part of the design-
process. But what needs to be done?
An indisputable fact is that the efficiency of any
energy conversion process is always less than
100%. This means that a part of the energy
being converted goes astray as heat and that
ultimately this waste heat must be removed.
The laws of thermodynamics state that heat
energy can only flow from a warmer to a
colder environment. So, for DC/DC converters,
this means that if the internal heat is to be
dissipated out of the module, that the ambient
temperature must always be lower than the
maximum allowable internal temperature. The
larger this difference, the more effectively
waste heat can flow out of the converter.
But which temperature specifications in the
datasheets are to be consulted for the thermal
calculations? RECOM declares two values in its
datasheets, Operating Temperature Range
(with or without derating) and the Maximum
Case Temperature. Some manufacturers even
claim that these two values are the same.
The case (surface) temperature of DC/DC
modules are typically given as around +100°C.
This value appears at first to be very high;
however this figure includes not only the self-
warming through internal losses but also the
ambient temperature itself.
Remember: The smaller the difference
between case surface and ambient, so the
smaller the amount of heat that can be lost to
the surroundings. If a converter has high
internal dissipation, then it will be more
affected by a small temperature difference
than a converter with low internal dissipation.
The internal losses occur mainly through
switching losses in the transistors, rectification
losses, core losses in the transformer and
resistive losses in the windings and tracks. The
maximum allowable internal temperature is
determined by either the curie temperature of
the transformer core material, the maximum
junction temperature of the switching
transistors or rectification diodes or the
maximum operating temperature of the
capacitors: whichever is the lowest.
Thermal Management-
Thermal Impedance
The Thermal Impedance is a measure of how
effectively heat can flow from inside the con-
verter to its surroundings. It is measured in
°C/Watt. It is possible to further lower the
thermal resistance to ambient by fitting an
external heat sink as this increases the surface
area from which heat can be transferred to the
surrounding air. The thermal impedance can
also be lowered by blowing air across the
converter as moving air can transfer more heat
away from the converter as stationary air.
Recom datasheets always show the thermal
impedance without a heatsink and with
natural convection (still air).
The datasheets also state the minimum and
maximum ambient operating temperature
rather than just the maximum case
temperature because this is easiest for the end
user to measure and to monitor. The advantage
is that true ambient temperature can be mea-
sured in the actual application and it need not
be calculated theoretically, plus the results are
valid for both sealed and vented constructions
with a through-flow of cooling air.
Nevertheless, the maximum case temperature
is useful to decide on a suitably dimensioned
heat sink so that the maximum case
temperature is not exceeded at the maximum
ambient temperature.
The internal losses and thermal resistances
can also be derived mathematically.
For the calculations, Ohm’s Law of R=V/I can
be modified so that R becomes thermal resi-
stance, V becomes temperature and I becomes
power dissipation. The following equations can
thus be derived:
where
R THcase-ambient = Thermal impedance
(from the case to the ambient surroundings)
T case =Case temperature
T ambient=Environment temperature
P dissipation =Internal losses
P in =Input power
P out =Output power
η(oper) =efficiency under the given operating
conditions
With help of the above formulae, the maximum
allowable ambient temperature for a given set
of operating conditions can be calculated - but
it is important to remember that efficiency is
dependent on both the output load and the
input voltage.
The formulae also demonstrate that case
temperature is not the same as operating
temperature, as is so often falsely claimed.
A practical example:
Take the RP30-4805SE with 80% load:
What is the maximum operating temp?
From the datasheet text and graphs, the
following information can be found:
R THcase-ambient = 10°C/W
T case = 100°C maximum
T ambient=unknown
P dissipation must be calculated from:
P out = 30 x 80% = 24W
η(oper) = 90% (from Eff vs Load Graph)
P diss. = 24/0.9 -24 = 2.66 Watts.
Thus
10W/°C = (100 - T amb) / 2.66W
and T amb max. = 73.4°C
At 100% load, this figure reduces to 64.4°C
At 100% load and over the full input voltage
range, this figure reduces further to 59.1°C
If the thermal dissipation calculations reveal
that the DC/DC Module will overheat at the
desired ambient operating temperature, then
there are still a number of options available to
reach a solution.
One option is to derate the converter, i.e, use a
higher power converter running at less than full
load. The derating diagrams in the datasheets
essentially define the maximum load at any
given temperature within the operating
temperature range. The derating curves are in
reality not so linear as they are declared in
most datasheets. However, reliable
manufacturers will always err on the safe side
so that the values given can be safely relied on
in practice.
If the converter has a plastic case, then the
next largest case size with the same power
rating could be chosen to increase the
available surface area. However, care must be
taken not to compromise on efficiency
otherwise no net gain will be made.
www.recom-international.com A-47
2009
Thermal Management-
Heat Sinking
If the converter has a metal case, then adding
a heat sink is can be very effective, particularly
in conjunction with a forced-air cooling system.
If a heat sink is used with fan cooling, then the
thermal resistance equation becomes:
RTHcase-ambient = RTHcase-heatsink + RTHheatsink-ambient
where
RTHcase-ambient =Thermal impedance
(from the case to the ambient surroundings)
RTHcase-heatsink =Thermal impedance
(from the case to the heat sink)
RTHheatsink-ambient =Thermal impedance
(from the heat sink to ambient)
The value of RTH heatsink-ambient includes
the thermal resistance of the heat sink as well
as the thermal resistance of any thermally
conductive paste or silicon pads used for a
better thermal contact to the case. If these heat
transfer aids are not applied, then a value of
approximately 0.2 K/W must be added to the
thermal resistance of the heat sink alone.
When establishing of the value of RTH
heatsink-ambient it is also necessary to know
how much air is being blown across the heat
sink fins. These values are most often given in
lfm (linear feet per minute) and declared by the
fan manufacturer. The conversion to m/s is
100lfm = 0.5 m/s.
Calculation of heatsinks size:
Example: RP30-2405SEW starts derating
without heatsink at +65°C but the desired
operation is 30W at +75°C so the size of
the heatsink has to be calculated.
Pout = 30W
Efficiency = 88% max.
Pd = Pout - Pout = 30W - 30W = 4.1W
Efficiency 88%
Tcase = 100°C (max. allowed case temperature)
Tambient = 75°C
RTHcase-ambient = Tcase-Tambient = 100°C-75°C
PD4.1°C
=6.1°C/W
So it has to be ensured that the thermal
resistance between case and ambient is
6,1°C/W max.
When mounting a heatsink on a case there is
a thermal resistance RTH case-heatsink between
case and heatsink which can be reduced by
using thermal conductivity paste but cannot be
eliminated totally.
Therefore, If a heatsink is mounted on the
converter, it’s thermal resistance has to be at
least:
RTHcase-ambient = RTHcase-heatsink + RTHheatsink-ambient =
6.1°C/W - 1°C/W = 5.1°C/W
If however, the results of your calculations or
measurements are border-line, then the issue
must be examined in more depth. So, for
example, there is a difference in thermal
performance between vertically and
horizontally mounted modules, between static
air and freely convecting air and with air at low
atmospheric pressures.
Heatsink mounted on case
without thermal conductivity paste RTH case-heatsink = ca. 1…2 °C/W
Heatsink mounted on case
with thermal conductivity paste RTH case-heatsink = ca. 0,5…1 °C/W
Heatsink mounted on case
with thermal conductivity paste
and electrical-isolation-film RTH case-heatsink = ca. 1…1,5 °C/W
2000 4000 8000 20000 40000 80000
1.0
0.8
0.6
0.4
0.2
0.0 0
ALTITUDE (FT)
NATURAL CONVECTION
EFFECTIVENESS
DC-DC Converter Applications
A-48 www.recom-electronic.com
2009
A : A
A : A ( 5 : 1mm)
1.30
1.30
1.30
1.40
2.00
1.40
49.80 ±0.2
24.20±0.2
12.00 ±0.2
12.00 ±0.2
R 0.65
1.2 ±0.1
3.2 ±0.1
5.60 ±0.1
1.70 ±0.1
R 2
7G-0020C (9.5°C/W)
7G-0047-F (12°C/W)
Heat Sinks available from Recom
Powerline DC-DC Application Notes
www.recom-international.com A-49
2009
7G-0011C (8.24°C/W)
A : A
A : A ( 5 : 1mm)
1.30
1.30
1.40
2.00
1.00
50.00 ±0.2
37.40±0.2
27.00 ±0.2
5.60 ±0.1
1.70 ±0.1
15.00 ±0.2
3.00 ±0.1
R 0.65
A : A
A : A ( 5 : 1mm)
1.30
1.30
1.30
1.40
1.30
1.40
49.80 ±0.2
49.80 ±0.2
12.00 ±0.2
12.00 ±0.2
R 0.65
1.2 ±0.1
3.2 ±0.1
5.60 ±0.1
1.70 ±0.1
7G-0026C (7.8°C/W)
Heat Sinks available from Recom
Powerline DC-DC Application Notes
A-50 www.recom-electronic.com
2009
AC/DC Application Notes
AC/DC
Converter
L
N
Adjustable
load
Time Delay
Fuse
+Vout
- Vout
AC/DC
Converter
L
N
Adjustable
load
Time Delay
Fuses
+Vout
- Vout
Live
Neutral
AC
INPUT
Input Fuse
Note: An input fuse is recommended for
safety and protection.
A time-delay or slo-blo fuse should be
fitted.
If the AC connector is not-polarised, then
fuses can be fitted to both inputs
Recommended Fuse Ratings
<40W 1.5Amp
40W 2 Amp
60W 3 Amp
AC/DC
Converter
L
NAdjustable
load
Time Delay
Fuse
+Vout
- Vout
Live
Neutral
Earth FG
Optional Link
Earthing
Note: If the converter has a ground pin
(FG), then it must be earthed to a safety
ground point.
Use thicker,shorter cables to ensure a
good connection as this will also reduce
the EMC interference.
-Vout can be also connected to FG to re-
ference the output to Ground.
AC/DC
Converter
L
NAdjustable
load
Time Delay
Fuse
+Vout
- Vout
Live
Neutral
Earth FG
Line
Filter
External Filter
Note: The RECOM RAC series contain a
built-in line filter to meet EN 55022 Class
B Conducted Emissions.
If additional filtering is required, then an
external line filter module can be fitted.
The cabling between the external filter
and the converter should be kept as
short as possible and a central star-earth
wiring should be used.
www.recom-international.com A-51
2009
AC/DC Application Notes
AC
DC
AC
DC
+Vo
2Vo
0V
0V
+Vo
N
L
AC
DC
AC
DC
+Vo
Vo
0V
0V
+Vo
N
L
Combining Converters
-in Parallel
Note: AC/DC converters can be
paralleled to increase the output voltage
or to make a hot-swap circuit.
The inputs of two AC/DC converters
cannot be wired in series to increase the
input voltage range
AC/DC
Converter
L
N
Main
load
Time Delay
Fuse
+Vout
0V
Live
Neutral
Earth FG
R-78xx
Aux.
load
AC/DC
Converter
L
N
Main
load
Time Delay
Fuse
+Vout
0V
Live
Neutral
Earth FG
DC
DC +Vo
-Vout
Note: A DC/DC converter or switching
regulator can be powered from the
output of an AC/DC converter to add an
auxilliary output or negative rail.
AC/DC
Converter
L
N
Adjustable
load
Time Delay
Fuse
+Vout
- Vout
200VDC
DC Inputs
Note: All AC/DC converters will also work
with DC inputs.
Check the individual datasheets for the
DC input voltage ranges.
Combining Converters
-in Series
A-52 www.recom-electronic.com
2009
Unregulated Single Output
RM, RL , RNM, RN, RQS, RO, RE,
ROM, RSS, R1S, RB-xxxxS,
RA-xxxxS, RBM-xxxxS, RK,
RP-xxxxS, RxxPxxS, RxxP2xxS,
R2S, RTS, RI, REZ, RKZ-xxxxS,
RV-xxxxS, RGZ
+Vout
-Vout
+Vin
-Vin
Oscillator
Unregulated Dual Output
RQD, RSD, R1D, RB-xxxxD,
RA-xxxxD, RBM-xxxxD, RH,
RP-xxxxD, RxxPxxD, RxxP2xxD,
RTD, R2D, RC-xxxxD, RD-xxxxD,
RKZ-xxxxD, RV-xxxxD, RJZ
+Vout
-Vout
+Vin
-Vin
Oscillator Com
Unregulated Dual Isolated Output
RU, RUZ
+Vout1
-Vout2
+Vin
-Vin
Oscillator -Vout1
+Vout2
Post-Regulated Single Output
RZ, RSZ (P), RY-xxxxS, RX-xxxxS, REC3-xxxxSR/H1
+Vout
-Vout
+Vin
-Vin
Oscillator
Reg
Post-Regulated Dual Output
RY-xxxxD, REC3-xxxxDR/H1
+Vout
-Vout
+Vin
-Vin
Oscillator Com
Reg
Reg
DC/DC Block Diagrams
Application Notes
www.recom-international.com A-53
2009
Regulated Single Output
RSO, RS, RW-xxxxS, REC3-xxxxSRW(Z)/H*, REC5-xxxxSRW(Z)/H*, REC7.5-xxxxSRW/AM/H*, RP08-xxxxSA,
RP08-xxxxSAW, RP10-xxxxSE, RP10-xxxxSEW, RP12-xxxxSA, RP12-xxxxSAW, RP15-xxxxSO, RP15-xxxxSOW, RP15-xxxxSA, RP15-xxxxSAW, RP15-xxxxSF,
RP15-xxxxSFW, RP20-xxxxSF, RP20-xxxxSFW
Noise
Filter +Vout
Isolation Reference
& Error AMP
-Vout
+Vin
-Vin
Oscillator &
Controller
Regulated Dual Output
RSO-xxxxD, RS-xxxxD, RW-xxxxD, REC3-xxxxDRW(Z)/H*, REC5-xxxxDRW(Z)/H*, REC7.5-xxxxDRW/AM/H*,
RP08-xxxxDA, RP08-xxxxDAW, RP10-xxxxDE, RP10-xxxxDEW, RP12-xxxxDA, RP12-xxxxDAW, RP15-xxxxDF, RP15-xxxxDFW, RP15-xxxxDA, RP15-xxxxDAW,
RP20-xxxxDF, RP20-xxxxDFW, RP30-xxxxDE, RP30-xxxxDEW, RP40-xxxxDG, RP40-xxxxDGW
Noise
Filter
Com
+Vout
Isolation Reference
& Error AMP
-Vout
+Vin
-Vin
Oscillator &
Controller
DC/DC Block Diagrams
Application Notes
A-54 www.recom-electronic.com
2009
Regulated Single Output, Synchronous Rectification
RP20-xxxxSF, RP30-xxxxSE, RP30-xxxxSEW, RP40-xxxxSG, RP40-xxxxSGW, RP60-xxxxSG
Switch
Control
Com
ON/OFF
Control
+Vout
Isolation Reference
& Error AMP Trim
+Vin
-Vin
PWM
Controller
Regulated Dual Output
RP40-05xxTG
Noise
Filter
+Vout1
Isolation Reference
& Error AMP
-Vout1
+Vin
-Vin
Oscillator &
Controller
Com
+Vaux
-Vaux
DC/DC Block Diagrams
Application Notes
www.recom-international.com A-55
2009
Rectifier
FG
Line Filter
+Vout
Isolation Reference
& Error AMP
-Vout
L
N
PWM
Controller
Rectifier
+Vout
Isolation Reference
& Error AMP
-Vout
L
N
PWM
Controller
RAC04-xxSA, RAC05-xxSA, RAC10-xxSA, RAC15-xxSA, RAC20-xxSA, RAC30-xxSA, RAC60-xxSB
RAC05-xxSB, RAC10-xxSB, RAC15-xxSB, RAC30-xxSB, RAC40-xxSA
AC/DC Block Diagrams
Application Notes
A-56 www.recom-electronic.com
2009
Rectifier
Filter
FG
Overcurrent
Protection
Com
+Vout
Isolation Reference
& Error AMP
-Vout
L
N
PWM
Controller
RAC05-xxDA, RAC10-xxDA, RAC15-xxDA, RAC20-xxDA, RAC30-xxDA
RAC15-xxDB, RAC30-xxDB, RAC40-xxSA
Rectifier
Filter
Overcurrent
Protection
+Vout
Isolation Reference
& Error AMP
-Vout
L
N
PWM
Controller
AC/DC Block Diagrams
Application Notes
www.recom-international.com A-57
2009
Rectifier
FG
Line Filter
Isolation Reference
& Error AMP
-Vout
L
N
PWM
Controller
+Vout
Com
+5Vout
+5V Rtn
Overcurrent
Protection
RAC15-05xxTA, RAC20-05xxTA
Rectifier
Line Filter
Isolation Reference
& Error AMP
-Vout
L
N
PWM
Controller
+Vout
Com
+5Vout
+5V Rtn
Overcurrent
Protection
RAC15-05xxTB, RAC30-05xxTA, RAC40-05xxTA
AC/DC Block Diagrams
Application Notes
A-58 www.recom-electronic.com
2009
No. Types
1. RO, RM, RN, RNM, RE, ROM, RB, RBM, RK, RH, RP, RU, RI, RD, RKZ, RUZ, RY,
R-78xx-0.5, R-78xx-1.0
2. RS, RSO, RS3, RxxTR
3. RJZ, RGZ, RW2(B)
4. RSS, RSD, RZ, R1S, R1D
5. RTD, RTS, RSZ, R-78Axx-xx SMD, R2S, R2D, R-78AAxx-xx SMD
6. RV, RW-S, RxxPxx, RxxP2xx, RW2(A)-SMD
7. R5-xxxxPA, R6xxxxP, R7xxxxP, RW-D,
REC3-, REC3.5, REC5-, REC6-, REC7.5-
8. RP08, RP12, RCD-24-xxx
9. RP15-O, RP15-OW, RP15-A, RP15-AW,
10. RP08-SMD, REC3-SMD, REC3.5-SMD, REC5-SMD, REC6-SMD, REC7.5-SMD
11. RP10, RP15, RP20, RP30, RP40
12. R-78Bxx-xx, R-78HBxx-xx
13. R-78Bxx-xxL, R-78HBxx-xxL
14. R5-xxxxDA, R6xxxxD, R7xxxxD
Transport Tubes
1. 2. 3.
TUBE LENGTH = 520±2.0 TUBE LENGTH = 520±1.5 TUBE LENGTH = 520±1.0
www.recom-international.com A-59
2009
7. 8.
Transport Tubes
4. 5. 6.
TUBE LENGTH = 530±2.0 TUBE LENGTH = 530±2.0 TUBE LENGTH =530±2.0
TUBE LENGTH = 530±2.0 TUBE LENGTH = 530±2.0
9. 10.
TUBE LENGTH = 530±2.0 TUBE LENGTH =530±2.0
A-60 www.recom-electronic.com
2009
Transport Tubes
20.0 ± 0.5
6.0 ± 0.5
15.0 ± 0.5
1.2 ± 0.2
50.0 ± 0.5
7.0 ± 0.5
TUBE LENGTH = 254mm ± 2.0
10.0 ± 0.5
54.0 ± 0.5
22.0 ± 0.5
11.
12. 13
23.8 ± 0.25
4.3 ± 0.25
0.63 ± 0.15 9.3 ± 0.25
18.5 ± 0.25
TUBE LENGTH = 520mm ± 2.0
17.8±0.25
10.2±0.25
0.7±0.2
6.5±0.25
9.2±0.25
5±0.25
3.3±0.25
11.1±0.25
14.
18.42±0.25
12.32±0.25
7.62± 0.25
17.15±0.25
11.68±0.25
TUBE LENGTH = 520mm ± 2.0
2.41±0.25
0.5± 0.127
www.recom-international.com A-61
2009
RSS(8)-xxxx & R1S(8)-xxxx tape outline dimensions
13.2
Spocket hole Ø1.50+0.1/-0
Spocket hole tolerance over any 10 pitches ±0.2
11.5
1.75
24.0 ±0.2
2.00
4.00
All dimensions in mm xx.xx ±0.1
1. 10 sprocket hole pitch cumulative tolerance ±0.20
2. All dimensions meet EIA-481-2 requirements
3. Component load per 13" reel : 500 pcs
4. The diameter of disc center hole is 13.0mm
RECOM
R1S-0505
xxxx
RECOM
R1S-0505
xxxx
RECOM
R1S-0505
xxxx
11.4
16.00
7.6
0.40 ±0.05
Tape and Reel (Suffix -R)
A-62 www.recom-electronic.com
2009
Tape and Reel (Suffix -R)
RSD(10)-xxxx, RSS12-xxxx, RSD12-xxxx, R1D(10)-xxxx, R1S12-xxxx, R1D12-xxxx,
& RZ-xxxx tape outline dimensions
17.75
Spocket hole Ø1.50+0.1/-0
Spocket hole tolerance over any 10 pitches ±0.2
11.5
1.75
24.0 ±0.2
2.00
4.00
All dimensions in mm xx.xx ±0.1
1. 10 sprocket hole pitch cumulative tolerance ±0.20
2. All dimensions meet EIA-481-2 requirements
3. Component load per 13" reel : 500 pcs
4. The diameter of disc center hole is 13.0mm
RECOM
RSD-0505
xxxx
RECOM
RSD-0505
xxxx
RECOM
RSD-0505
xxxx
11.4
16.00
7.6
0.35 ±0.05
www.recom-international.com A-63
2009
Tape and Reel (Suffix -R)
RSZ-xxxx, RTS-xxxx, R2S-xxxx, RTD-xxxx, R2D-xxxx
R-78Axx-xxSMD & R-78AAxx-xxSMD tape outline dimensions
15.5
Spocket hole Ø1.50+0.1/-0
Spocket hole tolerance over any 10 pitches ±0.2
11.5
1.75
24.0 ±0.3
2.00
4.00
All dimensions in mm xx.xx ±0.1
1. 10 sprocket hole pitch cumulative tolerance ±0.20
2. All dimensions meet EIA-481-2 requirements
3. Component load per 13" reel : 500 pcs
4. The diameter of disc center hole is 13.0mm
RECOM
RSZ-0505
xxxx
RECOM
RSZ-0505
xxxx
RECOM
RSZ-0505
xxxx
12.5
20.00
9.9
0.5 ±0.05
THINK GREEN - More than just a slogan.
THINK GREEN is a holistic concept to reduce energy consumption and waste at every stage of manu-
facture, use and disposal.
RECOM has developed a new series of DC-DC converters that are optimised to promote this THINK GREEN
concept.
MANUFACTURE: The RECOM factory is certified to EN14001:2005 for its Environmental Management
Systems. The aim of this standard is to reduce the environmental footprint of a business and to decrease the
pollution and waste a business produces. For RECOM, this has meant reducing the demand on natural
resources such as electricity and water used during production, introducing waste recycling throughout our
production and investigating ways of reducing or eliminating hazardous-to-the-environment chemicals
contained in the components used to build our converters.
DID YOU KNOW? - RECOM is already planning compliance with the new REACH (Reduction, Evaluation,
Authorization and restriction of Chemicals) proposals – even though the requirements are not due to come
into force until 2011!
USE: ICE (Innovation in Converter Excellence) Technology uses a combination of techniques to minimise
internal heat dissipation and maximise the heat transfer to ambient to create a new converter series which
offers high end performance at a price which is significantly lower than conventional specialist converters.
THINK GREEN: The new POWERLINE PLUS converters combine exceptional efficiency with very
low standby currents - thus energy loss is reduced at both full load and under no load conditions. Similar low
standby currents can also be found in our Innoline and Powerline AC-DC converters.
DID YOU KNOW? - A converter with 95% efficiency wastes half the energy of a converter with only
90% efficiency!
DISPOSAL: RECOM DC-DC and AC-DC converters are designed to give many years of service and offer
a level of reliability that the competition find hard to match. Due to the complex construction of a converter,
it is not possible to easily recycle a conventional module. RECOM has started to introduce open-frame
designs without the uses of epoxy or metal cases. This makes the disposal of end-of-life converters easier
as the converters can be ground up and any precious metals recovered by chemical means.
DID YOU KNOW? - We have converters still in active use that are more than 10 years old - and still going
strong!
THE NEXT GENERATION CONSTANT CURRENT HIGH POWER
DRIVER
LE
DRIVER
All-in-one
DRIVER
Fig. original size
- Ready to use - Plug & Play
- Up to 1.2A Constant Current
- PWM/Digital Dimming
- 100% linear Analog Dimming
- 96% Efficiency
- Wide Input Voltage Range
- Low Emissions (EN-55022)
- Long lifetime up to 600,000hrs.
- Ultra Miniature Design
- High op. temperature/85oC
NEW!
Wired version.
No more designing, certifying and procuring.
RECOM Power, Inc.
18 Bridge Street
Unit 4C
Brooklyn, NY 11201, USA
Phone: (+1) 718-855-9710
Fax: (+1) 718-855-9714
admin@recom-power.com
www.recom-power.com
RECOM ELECTRONIC -THE NETWORK
RECOM Asia Pte Ltd
Block 1003, Technopreneur Centre
Bukit Merah Central, # 04-30
159836 Singapore
Phone: (+65) 6276-8795
Fax: (+65) 6273-1477
Mobile: (+65) 9788-0774
enquiry@recomasia.com
www.recomasia.com
RECOM Application Engineering
Support Center
Krottenseestraße 45,
A-4810 Gmunden
Phone: +43 (0) 7612-9003-3101
Fax: +43 (0) 7612-9003-3130
info@recom-development.at
www.recom-electronic.com
RECOM ELECTRONIC GmbH
Otto-Hahn-Str. 60
D-63303 Dreieich
Germany
Phone: +49-(0)6103-30007-0
Fax: +49-(0)6103-30007-61
info@recom-electronic.com
www.recom-electronic.com
www.recom-electronic.com/contacts
Let us help you to find the right solution. Contact our Customer Service or find a Sales Representative.
With offices around the world, we are eager to help you meet your needs. Our highly trained sales
staff and our technical engineers can help you find the right solution for your power application.
RECOM Asia Pte Ltd
Shanghai Office
Rm 8205, 2F Building A,
Jiahua Business Center
No. 808 Hongqiao Rd
Shanghai, China
Phone: +86 (21) 6448-1990
Fax: +86 (21) 6448-0511
enquiry@recomasia.com
www.recomasia.com
RECOM ELECTRONIC uses ICE Technology. A combination of techniques
to minimise internal heat dissipation and maximise the heat transfer to
ambient to create a new converter series which offers high end performance
at a price which is significantly lower than conventional specialist converters.
RECOM - Green high-efficiency power solutions. SAVE ENERGY. NOW.
