Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 1
Technical
Specification
SQ60120HZx50
Contents
Operational Features
• High efciency, 95% at full rated load current
• Delivers up to 50A of output current (600W) with optional baseplate
conguration
• Output droop characteristic allows direct parallel operation
• Operating input voltage range: 35-75Vdc
• Fixed frequency switching provides predictable EMI
• No minimum load requirement
Protection Features
• Input under-voltage lockout disables converter at low Vin conditions
• Output current limit and short circuit protection protects converter
and load from permanent damage and hazardous conditions
• Active back bias limit provides smooth startup with
external load induced pre-bias
• Thermal shutdown protects from abnormal environmental conditions
SQ60120HZx50 Model
Control Features
• On/Off control referenced to input side (positive and negative logic
options are available)
Mechanical Features
• Industry standard pin-out conguration
• Standard Size Open Frame:2.39" x 2.49" (60.6 x 63.1mm)
• Total Open Frame height only 0.420” (10.67mm),
permits better airow and smaller card pitch
• Open Frame Weight: 2.6 oz. (75g)
• Flanged pins designed to permit surface mount soldering
(avoid wave solder) using FPiP technique
The SQ60120HZx50 bus converter is a next-
generation, board-mountable, isolated, xed
switching frequency dc/dc converter that uses
synchronous rectication to achieve extremely high
conversion efciency. The power dissipated by the
converter is so low that a heatsink is not required,
which saves cost, weight, height, and application
effort. The SQ BusQor series provides an isolated
step down voltage from 48V to a semi-regulated 12V
intermediate bus. BusQor converters are ideal for
customers who need multiple outputs and wish to
build or buy point of load converters to work with a
12V rail. RoHS Compliant (see last page).
Safety Features
• UL 60950-1:R2011-12
• EN60950-1/A12:2011
• CAN/CSA-C22.2 No. 60950-1/A1:2011
35-75V 100V 12Vout 600W 2250V dc Half-brick
Continuous Input Transient Input Semi-Regulated Max Power Isolation DC-DC Converter
Page No.
Open Frame Mechanical Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Baseplated Mechanical Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electrical Characteristics...................................4
Standards & Qualifications ................................. 6
Figures............................................... 7
Application Section ..................................... 10
Ordering Information.................................... 14
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 2
Technical
Specification
SQ60120HZx50
Open Frame Mechanical Diagram
Open Frame Mechanical Diagram
mech01
2.40
[61]
.400[10.16]
.700[17.78]
1.000[25.4]
1.400[35.56]
.50[12.7]
.400[10.16]
1.400
[35.56]
2.30
[58.4]
.19
[4.8]
1.90
[48.3]
TOP VIEW
OVERALL HEIGHT
.413 ± .017
10.49 ± 0.43[ ] .180
[4.57]
SEE NOTE 3
BOTTOMSIDE
CLEARANCE
.044 ± .027
1.12 ± 0.68[ ]
SIDE VIEW
5
6
7
8
9
124
NOTES
1) Pins 1, 2 & 4, 6-8 are 0.040” (1.02mm) dia. with 0.080" (2.03mm)
standoff shoulders.
2) Pins 5 & 9 are 0.080” (1.57mm) dia. with 0.125" (2.54mm) standoff
shoulders.
3) Other pin extension lengths available.
4) All Pins: Material - Copper Alloy
Finish: Matte Tin over Nickel Plate
5) Undimensioned components are shown for visual reference only.
6) All dimensions in inches (mm)
Tolerances: X.XXin +/- 0.02 (X.Xmm +/- 0.5mm)
X.XXXin +/- 0.010 (X.XXmm +/- 0.25mm)
7) Open Frame Weight: 2.6 oz. (75g)
8) Workmanship: Meets or exceeds IPC-A-610 Class II
PIN DESIGNATIONS
Pin Name Function
1 Vin(+) Positive input voltage
2 ON/OFF TTL input to turn converter on and off,
referenced to Vin(–), with internal pull up.
4 Vin(–) Negative input voltage
5 Vout(–) Negative output voltage
6 Not Present Not applicable
7 Not Present Not applicable
8 Not Present Not applicable
9 Vout(+) Positive output voltage
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 3
Technical
Specification
SQ60120HZx50
Baseplated Mechanical Diagram
mech02
NOTES
1) M3 screws used to bolt unit's baseplate to other surfaces such as
heatsink must not exceed 0.100" (2.54mm) depth below the surface
of the baseplate.
2) Applied torque per screw should not exceed 6in-lb (0.7Nm).
3) Other pin extension lengths available.
4) Pins 1, 2 & 4, 6-8 are 0.040” (1.02mm) dia. with 0.080" (2.03mm)
standoff shoulders.
5) Pins 5 & 9 are 0.080” (1.57mm) dia. with 0.125" (2.54mm) standoff
shoulders.
6) Baseplate atness tolerance is 0.004" (.10mm) TIR for surface.
7) All Pins: Material - Copper Alloy
Finish: Matte Tin over Nickel Plate
8) Undimensioned components are shown for visual reference only.
9) All dimensions in inches (mm)
Tolerances: X.XXin +/- 0.02 (X.Xmm +/- 0.5mm)
X.XXXin +/- 0.010 (X.XXmm +/- 0.25mm)
10) Weight: 4.3 oz. (123g)
11) Workmanship: Meets or exceeds IPC-A-610 Class II
PIN DESIGNATIONS
Pin Name Function
1 Vin(+) Positive input voltage
2 ON/OFF TTL input to turn converter on and off,
referenced to Vin(–), with internal pull up.
4 Vin(–) Negative input voltage
5 Vout(–) Negative output voltage
6 Not Present Not applicable
7 Not Present Not applicable
8 Not Present Not applicable
9 Vout(+) Positive output voltage
.400[10,16]
.700[17,78]
1.000[25,4]
1.400[35,56]
.180
[4,57]
SEE NOTE 3
BOTTOMSIDE
CLEARANCE
.044± .027
1,12± 0,68[ ]
SIDE VIEW
OVERALL HEIGHT
.495± .024
12,57± 0,6[ ]
TOP VIEW
M3 THREADED INSERT
4 PLACES
SEE NOTE 1
.50[12,7]
.400[10,16]
1.400
[35,56]
.19
[4,8]
1.90
[48,3]
2.30
[58,4]
2.40
[61]
124
5
6
7
8
9
Baseplated Mechanical Diagram
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 4
Technical Specification
Input:35-75V
Output:12V
Current:50A
Part No.:SQ60120HZx50
Electrical Characteristics
SQ60120HZx50 Electrical Characteristics
Ta = 25 °C, airow rate = 300 LFM, Vin = 48 V dc unless otherwise noted; full operating temperature range is -40 °C to +100 °C baseplate temperature
with appropriate power derating. Specications subject to change without notice.
Parameter Min. Typ. Max. Units Notes & Conditions
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Non-Operating 0 100 V Continuous
Operating 80 V Continuous
Operating Transient Protection 100 V 100 ms transient, square wave
Isolation Voltage
Input to Output 2250 V
Operating Temperature -40 100 °C
Storage Temperature -55 125 °C
Voltage at ON/OFF input pin -2 18 V
INPUT CHARACTERISTICS
Operating Input Voltage Range 35 48 75 V
Input Under-Voltage Lockout
Turn-On Voltage Threshold 31.5 33.0 34.5 V
Turn-Off Voltage Threshold 29.0 30.5 32.0 V
Lockout Voltage Hysteresis 1.5 2.5 3.5 V
Maximum Input Current 20 A 100% Load, 35 Vin
No-Load Input Current 125 200 mA
Disabled Input Current 20 40 mA
Inrush Current Transient Rating A2s
Response to Input Transient 1.0 V 0.25V/μs input transient
Input Reected-Ripple Current 5 20 mA RMS thru 4.7μH inductor
Input Terminal-Ripple Current 220 mA RMS
Recommended Input Fuse 30 A Fast blow external fuse recommended
Recommended External Input Capacitance 220 µF Typical ESR 0.1-0.2 Ω; Figure 11
Input Filter Component Values (C\L\C) 22\0.75\11 nF\µH\µF Internal values; Figure H
OUTPUT CHARACTERISTICS
Output Voltage Set Point 12.00 12.20 12.35 V At zero load; semi-regulated
Output Voltage Regulation
Over Line -1.5/180 V Relative to nominal line
Over Load -4.5/540 mV Relative to zero load; semi-regulated
Over Temperature ±1.5/180 mV At full load: drift at zero load is minimal
Total Output Voltage Range 11.0 12.6 V Over sample, line, load, temperature & life
Output Voltage Ripple and Noise 20 MHz bandwidth; see Note 1
Peak-to-Peak 90 150 mV Full load
RMS 20 30 mV Full load
Operating Output Current Range 0 50 A Subject to thermal derating
Output DC Current-Limit Inception 55.0 60.0 65.0 A Output Voltage 10% Low
Output DC Current-Limit Shutdown Voltage 5 V See note 2
Back-Drive Current Limit while Enabled 13 18 23 A Negative current drawn from output source
Back-Drive Current Limit while Disabled 0 3 4 mA Negative current drawn from output
Maximum Output Capacitance 12 mF Nominal Vout at full load (resistive load)
EFFICIENCY
100% Load 94.5 95.0 % Figures 1 - 2
50% Load 96.5 % Figures 1 - 2
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 5
Technical Specification
Input:35-75V
Output:12V
Current:50A
Part No.:SQ60120HZx50
SQ60120HZx50 Electrical Characteristics (continued)
Ta = 25 °C, airow rate = 300 LFM, Vin = 48 V dc unless otherwise noted; full operating temperature range is -40 °C to +100 °C baseplate temperature
with appropriate power derating. Specications subject to change without notice.
Parameter Min. Typ. Max. Units Notes & Conditions
DYNAMIC CHARACTERISTICS
Output Voltage during Load Current Transient
Step Change in Output Current (0.1A/µs) 350 mV 50% to 75% to 50% Iout max, 470 μF load cap
Step Change in Output Current (5A/µs) 500 mV
Settling time 1 ms To within 1% Vout nom
Turn-On Transient
Turn-On Time 27 ms Full load, Vout=90% nom; Figures 9 & 10
Output Voltage Overshoot 2 % 12 mF load capacitance, Iout = 0A
ISOLATION CHARACTERISTICS
Isolation Voltage (dielectric strength) 2250 V See Absolute Maximum Ratings
Isolation Resistance 30 MΩ
Isolation Capacitance (input to output) 1000 pF See note 3
TEMPERATURE LIMITS FOR POWER DERATING CURVES
Semiconductor Junction Temperature 125 °C Package rated to 150°C
Board Temperature 125 °C UL rated max operating temp 130°C
Transformer Temperature 125 °C
FEATURE CHARACTERISTICS
Switching Frequency Regulation Stage 235.5 238.0 240.5 kHz Over sample, temp & life
Switching Frequency Isolation Stage 117.75 119.00 120.25 kHz Over sample, temp & life
ON/OFF Control (Option P)
Off-State Voltage -2.0 1.0 V
On-State Voltage 4.0 18.0
ON/OFF Control (Option N)
Off-State Voltage 4.0 18.0 V
On-State Voltage -2.0 1.0
ON/OFF Control (Either Option) Application notes; Figures A & B
ON/OFF Control Hysteresis 1.5 °C
Pull-Up Voltage 4.75 5.00 5.25 V
Pull-Up Resistance 10 kΩ
Output Over-Voltage Protection 113 118 123 % Over Full Temperature Range; % of nominal Vout
Over-Temperature Shutdown 120 °C Average PCB Temperature
Over-Temperature Shutdown Restart Hysteresis 10 °C
RELIABILITY CHARACTERISTICS
Calculated MTBF (Telcordia) 2.1 106 Hrs. TR-NWT-000332; 80% load, 300LFM, 40°C Ta
Calculated MTBF (MIL-217) 1.9 106 Hrs. MIL-HDBK-217F; 80% load, 300LFM, 40°C Ta
Field Demonstrated MTBF 106 Hrs. See our website for details
Note 1: For applications requiring reduced output voltage ripple and noise, consult SynQor applications support (e-mail: support@synqor.com)
Note 2: If the output voltage falls below the Output DC Current Limit Shutdown Voltage for more than 50ms, then the unit will enter into hiccup mode,
with a 500ms off-time.
Note 3: Higher values of isolation capacitance can be added external to the module.
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 6
Technical Specification
Input:35-75V
Output:12V
Current:50A
Part No.:SQ60120HZx50
Standards & Qualifications
Standards Compliance & Qualification Testing
Parameter Notes & Conditions
STANDARDS COMPLIANCE
UL 60950-1:R2011-12 Basic insulation
EN60950-1/A12:2011
CAN/CSA-C22.2 No. 60950-1/A1:2011
Note: An external input fuse must always be used to meet these safety requirements. Contact SynQor for ofcial safety certicates on new
releases or download from the SynQor website.
Parameter # Units Test Conditions
QUALIFICATION TESTING
Life Test 32 95% rated Vin and load, units at derating point, 1000 hours
Vibration 5 10-55 Hz sweep, 0.060" total excursion, 1 min./sweep, 120 sweeps for 3 axis
Mechanical Shock 5 100g minimum, 2 drops in x, y and z axis
Temperature Cycling 10 -40 °C to 100 °C, unit temp. ramp 15 °C/min., 500 cycles
Power/Thermal Cycling 5 Toperating = min to max, Vin = min to max, full load, 100 cycles
Design Marginality 5 Tmin-10 °C to Tmax+10 °C, 5 °C steps, Vin = min to max, 0-105% load
Humidity 5 85 °C, 95% RH, 1000 hours, continuous Vin applied except 5 min/day
Solderability 15 pins MIL-STD-883, method 2003
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 7
Technical Specification
Input:35-75V
Output:12V
Current:50A
Part No.:SQ60120HZx50
0
5
10
15
20
25
30
35
40
45
50
25 40 55 70 85
Ambient Air Temperature (
o
C)
I
out
(A)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
80
82
84
86
88
90
92
94
96
98
100
0 10 20 30 40 50
Load Current (A)
Efficiency (%)
35Vin
48Vin
75Vin
0
5
10
15
20
25
30
35
40
45
50
0 10 20 30 40 50
Load Current (A)
Power Dissipation (W)
35Vin
48Vin
75Vin
Semiconductor junction temperature is
within 1
°
C of surface temperature
Figures
0
5
10
15
20
25
30
35
40
45
50
25 40 55 70 85
Ambient Air Temperature (
o
C)
I
out
(A)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
Figure 1: Efciency at nominal output voltage vs. load current for minimum,
nominal, and maximum input voltage at 25°C.
Figure 2: Power dissipation at nominal output voltage vs. load current for
minimum, nominal, and maximum input voltage at 25°C.
Figure 3: Maximum output power derating curves vs. ambient air temperature
for airow rates of 100 LFM through 400 LFM with air owing across the
converter from pin 5 to pin 9 (nominal input voltage).
Figure 4: Thermal plot of converter at 36A load current (432W) with 55°C air
owing at the rate of 200 LFM. Air is owing across the converter from pin 5 to
pin 9 (nominal input voltage).
Figure 5: Maximum output power derating curves vs. ambient air temperature
for airow rates of 100 LFM through 400 LFM with air owing from input to
output (nominal input voltage).
Figure 6: Thermal plot of converter at 36A load current (432W) with 55°C air
owing at the rate of 200 LFM. Air is owing across the converter from input to
output (nominal input voltage).
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 8
Technical Specification
Input:35-75V
Output:12V
Current:50A
Part No.:SQ60120HZx50
Figure 7: Turn-on transient at full load (resistive load) (10 ms/div).
Ch 1: Vout (5V/div)
Ch 2: ON/OFF input (5V/div)
Figure 8: Turn-on transient at zero load (10 ms/div).
Ch 1: Vout (5V/div)
Ch 2: ON/OFF input (5V/div)
Figure 9: Output voltage response to step-change in load current [50%-75%-
50% of Iout(max); dI/dt = 0.1A/μs]. Load cap: 1μF ceramic and 470μF, 15mW
ESR electrolytic capacitors. Top trace: Vout (500mV/div), Bottom trace: Iout
(25A/div).
Figure 10: Output voltage response to step-change in load current [50%-75%-
50% of Iout(max): dI/dt = 5A/μs]. Load cap: 470μF, 15mW ESR electrolytic
capacitor. Top trace: Vout (500mV/div), Bottom trace: Iout (25A/div).
Figure 11: Test set-up diagram showing measurement points for Input Terminal
Ripple Current (Figure 12), Input Reected Ripple Current (Figure 13) and
Output Voltage Ripple (Figure 14).
Figure 12: Input Terminal Ripple Current, ic, at full rated output current and
nominal input voltage with 4.7μH source impedance and 220μF electrolytic
capacitor (1 A/div, 2 μs/div). See Figure 11.
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 9
Technical Specification
Input:35-75V
Output:12V
Current:50A
Part No.:SQ60120HZx50
11.4
11.5
11.6
11.7
11.8
11.9
12.0
12.1
12.2
12.3
12.4
0 5 10 15 20 25 30 35 40 45 50
Load Current (A)
Output Voltage (V)
Figure 13: Input reected ripple current, is, through a 4.7μH source inductor,
using a 220μF input capacitor, at nominal input voltage and rated load current
(10 mA/div, 2 μs/div). See Figure 11.
Figure 14: Output voltage ripple at nominal input voltage and rated load current
(50 mV/div, 2 μs/div). Load capacitance: 1μF ceramic capacitor and 15μF
tantalum capacitor. Bandwidth: 20 MHz. See Figure 11.
Figure 15: Output voltage response to step-change in input voltage (35V to 75V
in 300μs, 1 ms/div). Load cap: 470μF, 15mW ESR electrolytic capacitor. Ch 1:
Vout (500mV/div), Ch 2: Vin (10V/div), at zero load current.
Figure 16: Load current (10A/div; 10ms/div) as a function of time when the
converter attempts to turn on into a 1 mW short circuit.
Figure 17: Output voltage vs. load current showing droop characteristic at 25°C.
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 10
Technical
Specification
SQ60120HZx50
Application Section
Application Section
BASIC OPERATION AND FEATURES
The Zeta series converter uses a two-stage power conversion
topology. The first stage keeps the output voltage constant over
variations in line, load, and temperature. The second stage uses a
transformer to provide the functions of input/output isolation and
voltage step-down to achieve the low output voltage required.
Both the first stage and the second stage switch at a fixed frequency
for predictable EMI performance. Rectification of the transformer’s
output is accomplished with synchronous rectifiers. These devices,
which are MOSFETs with a very low on-state resistance, dissipate
significantly less energy than Schottky diodes, enabling the con-
verter to achieve high efficiency.
Dissipation throughout the converter is so low that it does not
require a heatsink for operation. Since a heatsink is not required,
the converter does not need a metal baseplate or potting material
to help conduct the dissipated energy to the heatsink. As an open
frame module, the converter can be built more simply and reliably
using high yield surface mount techniques on a PCB substrate.
The half-brick series converters use the industry standard footprint
and pin-out configuration.
CONTROL FEATURES
REMOTE ON/OFF (Pin 2): The ON/OFF input, Pin 2, permits the
user to control when the converter is or . This input is referenced
to the return terminal of the input bus, Vin(-). The converter is avail-
able with either positive or negative logic used for the ON/OFF input.
In the positive logic version, the ON/OFF input is active high (mean-
ing that a high voltage turns the converter ). In the negative logic
version, the ON/OFF signal is active low (meaning that a low voltage
turns the converter ). Figure A details five possible circuits for driv-
ing the ON/OFF pin.
PROTECTION FEATURES
Input Under-Voltage Lockout: The converter is designed to
turn off when the input voltage is too low, helping to avoid an input
system instability problem, which is described in more detail in the
application note titled “Input System Instability”
on the SynQor
website
. The lockout circuitry is a comparator with DC hysteresis.
When the input voltage is rising, it must exceed the typical “Turn-On
Voltage Threshold” value* before the converter will turn on. Once
the converter is on, the input voltage must fall below the typical
Turn-Off Voltage Threshold value before the converter will turn off.
Output Current Limit: If the output current exceeds the “Output
DC Current Limit Inception” point*, then a fast linear current limit
controller will reduce the output voltage to maintain a constant
output current.
If as a result, the output voltage falls below the
“
Output DC Current Limit Shutdown Voltage
”
* for more than
50ms, then the unit will enter into hiccup mode, with a 500ms
off-time. The unit will then automatically attempt to restart.
Back-Drive Current Limit: If there is negative output current
of a magnitude larger than the “Back-Drive Current Limit while
Enabled” specification*, then a fast back-drive limit controller will
increase the output voltage to maintain a constant output current.
If this results in the output voltage exceeding the “Output Over-
Voltage Protection” threshold*, then the unit will shut down. The full
I-V output characteristics can be seen in Figure 17.
Output Over-Voltage Limit: If the voltage directly across the
output pins exceeds the “Output Over-Voltage Protection” thresh-
old*, the converter will immediately stop switching. This shutdown is
latching; unlike other shutdown types, the converter will not restart
unless the input power is cycled or the ON/OFF input is toggled.
Over-Temperature Shutdown: A temperature sensor on the
converter senses the average temperature of the module. The ther-
mal shutdown circuit is designed to turn the converter off when the
temperature at the sensed location reaches the “Over-Temperature
Shutdown” value*. It will allow the converter to turn on again when
the temperature of the sensed location falls by the amount of the
“Over-Temperature Shutdown Restart Hysteresis” value*.
Figure A: Various circuits for driving the ON/OFF pin.
Open Collector Enable Circuit
Remote Enable
Circuit
Direct Logic Drive
Negative Logic
(Permanently
Enabled)
(Permanently
Enabled)
ON/OFF
Vin(-) Vin(-) Vin(-)
ON/OFF
ON/OFF
Vin(_)
ON/OFF
5V
CMOS
Vin(_)
Positive Logic
ON/OFF
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 11
Technical
Specification
SQ60120HZx50
Application Section
APPLICATION CONSIDERATIONS
Droop based current sharing is implemented by only regulating the
output of first stage in the two-stage power conversion topology.
The inherent impedance of the second stage balances current
between multiple modules. This scheme ensures redundancy since
there is no active current sharing circuit or common connection
to fail. Graphs in this section show two units by way of example,
but there is no fundamental limit to the number of units that can
be placed in parallel. While the lack of output voltage regulation
can seem to be a disadvantage, as we will discuss, it can actually
reduce the overall voltage deviation when transient response is
considered. Another hidden advantage of droop sharing is a
dramatic stability improvement of any external post-regulators.
Droop Damps Downstream Point-of-Loads: It is very
common to have additional non-isolated point-of-load converters
downstream of an isolated bus converter, called an Intermediate
Bus Architecture (IBA). Each of these point-of-load converters
requires damping to keep its input system stable. Since the point-
of-load converter input current goes up when the bus voltage goes
down, it presents an incremental negative resistance. This will be
unstable when coupled with a low impedance source, parasitic or
explicit inductance, high power, and low bus voltage. The usual
solution is to add large amounts of bulk capacitance with inherent
or explicit equivalent series resistance to provide damping (See
Figure 4 in Input System Instability whitepaper). The downside of
this approach is that the capacitors are expensive and bulky. An
alternate solution is to add an explicit series resistance, but this is
undesirable because of the additional power loss (See Figure 3 in
Input System Instability whitepaper).
A bus converter with a droop characteristic has an inherent
series resistance, without the need for any additional
components. Since this resistance comes from the transformer
and output rectifiers of the bus converter, it does not represent
any additional power loss. The value of this positive damping
resistance can be derived directly from the slope of the bus
converter output voltage droop characteristic vs. output
current. Stability can be determined by evaluating equations
3-6 in the Input System Instability whitepaper.
Voltage Mismatch Impacts Share Accuracy: When multiple
units having droop characteristics are placed in parallel, the current
sharing accuracy is determined by the output voltage accuracy.
A difference in voltage between two units will cause a differential
current to flow out of one unit and into the other. Figure B shows
an example with two units with output voltage mismatched by
0.5%. In this example, when Unit A is at 100% of its full rated
load current, Unit B is only at 90%, effectively reducing the total
available current by 5%. SynQor uses factory calibration of each
unit to ensure that output voltage is well matched.
-6%
-5%
-4%
-3%
-2%
-1%
0%
0% 20% 40% 60% 80%
100%
Load Current (% of Rated Value)
Output Voltage Droop (% of Nominal)
Unit A
Unit B
Figure B: Droop Characteristics with Voltage Mismatch
Temperature Mismatch Self Balancing: The slope of the
output voltage droop characteristic increases with increased
temperature. So, if a paralleled unit were hotter than its neighbor,
then it would take more of the load current. However, this
situation is self correcting, because as a converter heats up, its
droop increases due to an increase in output resistance. As shown
in Figure C, this causes the hotter unit to share less current, which
in turn cools down and restores equilibrium.
-6%
-5%
-4%
-3%
-2%
-1%
0%
0% 20% 40% 60% 80%
100%
Load Current (% of Rated Value)
Output Voltage Droop (% of Nominal)
Unit A (cooler)
Unit B (hotter)
Figure C: Droop Characteristics with Temperature Mismatch (Self Balancing)
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 12
Technical
Specification
SQ60120HZx50
Application Section
Improved Transient Response: While a droop characteristic
degrades load regulation, it also improves voltage overshoot in
response to a fast removal of load current. This is because the
output voltage starts lower when the load is higher. Figure D
shows that a droop characteristic can actually reduce the total
output voltage deviation caused by variations in load, when the
load transient response is taken into account. Note that with zero
or low output capacitance, there will be an additional immediate
voltage overshoot present on a 100µs time scale.
Figure D: Output voltage response to full load step change in output current (Ch2),
compared to a fully regulated HZA model (Ref2). 12mF output capacitance.
No output trim or remote sense: Droop share converters
do not have remote sense or trim functions, and as such, the
corresponding pins are not present. Remote sense and trim
would actually interfere with the droop behavior and prevent
proper current sharing by maintaining the output voltage of
each converter as load current varies. As a result, when placed
in parallel, the converter with the highest output voltage would
carry the entire load.
In many applications, the output is fed to low-voltage point-of-
load converters, which have their own regulating control loops
that can easily correct for a range of input voltages.
Output ORing Devices: For system designs requiring redundancy,
the converters can be configured either of two ways:
• Directly in parallel
• Paralleled through Or’ing diodes or FETs.
For direct paralleling, the output FETs in the power converter
and a few control components are the only non-redundant
electronic parts that could be single points of failure. Depending
on the required MTBF, this may be a good alternative. On
request, SynQor can provide predicted MTBF information on
these parts for specific models.
For the highest MTBF, the outputs can be OR’d with series
diodes or MOSFETs. With droop sharing in this configuration,
there are essentially no single points of failure, since there is
no explicit control connection between units, as in an active
current sharing solution.
For the best load current sharing accuracy, ORing diodes should
be exactly the same type and held to the same temperature as
much as possible. Minor differences in the forward drop of these
components will affect sharing performance.
Limited Output Voltage Resolution: The internal voltage
control feedback loop has limited resolution. Therefore, the
output voltage will exhibit discrete steps as the loop responds to
changes in line or load. For instance, on close examination, the
startup ramp has a “stair-step” shape. Likewise, a load transient
response will be composed of multiple discrete steps. The size of
each step is well determined, and is shown in Figure E. A close-
up picture of a single step is shown in Figure F. Stepping will not
occur under steady state conditions.
0
20
40
60
80
100
120
140
35 40 45 50 55 60 65 70
75
Vin (V)
Vout Step Size (mV)
= 12.0 Vout
= 10.0 Vout
≤ 8.75 Vout
Figure E: Output voltage resolution.
* See Electrical Characteristics page.
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 13
Technical
Specification
SQ60120HZx50
Application Section
Input System Instability: This condition can occur because any
DC/DC converter appears incrementally as a negative resistance
load. A detailed application note titled “Input System Instability” is
available on the SynQor website which provides an understanding
of why this instability arises, and shows the preferred solution for
correcting it.
Application Circuits: Figure G provides a typical circuit diagram
which details the input and output filtering.
Figure F: Smallest possible Vout step at 48Vin and 12Vout.
Input Filtering and External Input Capacitance: Figure H
below shows the internal input filter components. This filter
dramatically reduces input terminal ripple current, which otherwise
could exceed the rating of an external electrolytic input capacitor.
The recommended external input capacitance is specified in the
Input Characteristics section on the Electrical Specifications page.
More detailed information is available in the application note titled
“EMI Characteristics” on the SynQor website.
Output Filtering and External Output Capacitance: Figure H
below shows the internal output filter components. This filter dra-
matically reduces output voltage ripple. However, some minimum
external output capacitance is required, as specified in the Output
Characteristics section on the Electrical Specifications page. No
damage will occur without this capacitor connected, but peak out-
put voltage ripple will be much higher.
C2
C1
Lin
Vin(+)
Vin(_)
Vout (+)
Vout (-)
Regulation
Stage
Current
Sense
Isolation
Stage
Figure H: Internal Input and Output Filter Diagram (component values listed on specifications page).
Vin
External
Input
Filter
Vout (+)Vin (+)
Vout (-)Vin (-) Iload
Cload
ON/OFF
Electrolytic
Capacitor
220µF
ESR ≅ 2Ω
Figure G: Typical application circuit (negative logic unit, permanently enabled).
Product # SQ60120HZx50 Phone 1-888-567-9596 www.synqor.com Doc.# 005-0005134 Rev. D 05/30/13 Page 14
Technical
Specification
SQ60120HZx50
Ordering Information
Part Numbering System
The part numbering system for SynQor’s dc-dc converters follows the format
shown in the example below.
The first 12 characters comprise the base part number and the last 3
characters indicate available options. The “-G” suffix indicates 6/6 RoHS
compliance.
Application Notes
A variety of application notes and technical white papers can be downloaded
in pdf format from our website.
RoHS Compliance: The EU led RoHS (Restriction of Hazardous
Substances) Directive bans the use of Lead, Cadmium, Hexavalent
Chromium, Mercury, Polybrominated Biphenyls (PBB), and Polybrominated
Diphenyl Ether (PBDE) in Electrical and Electronic Equipment. This SynQor
product is 6/6 RoHS compliant. For more information please refer to
SynQor’s RoHS addendum available at our RoHS Compliance / Lead Free
Initiative web page or e-mail us at rohs@synqor.com.
Ordering Information
The tables below show the valid model numbers and ordering options for
converters in this product family. When ordering SynQor converters, please
ensure that you use the complete 15 character part number consisting of
the 12 character base part number and the additional characters for options.
Add “-G” to the model number for 6/6 RoHS compliance.
The following options must be included in place of the
w x y z
spaces in the
model numbers listed above.
Not all combinations make valid part numbers, please contact SynQor for
availability.
Warranty
SynQor offers a three (3) year limited warranty. Complete warranty
information is listed on our website or is available upon request from
SynQor.
Information furnished by SynQor is believed to be accurate and reliable.
However, no responsibility is assumed by SynQor for its use, nor for any
infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any
patent or patent rights of SynQor.
Product Family
Package Size
Performance Level
Thermal Design
Output Current
6/6 RoHS
Options (see
Ordering Information)
Input Voltage
Output Voltage
Contact SynQor for further information and to order:
Phone: 978-849-0600
Toll Free: 888-567-9596
Fax: 978-849-0602
E-mail: power@synqor.com
Web:
www.synqor.com
Address: 155 Swanson Road
Boxborough, MA 01719
USA
SQ 60 1 2 0 H Z B 50 N N S - G
PATENTS
SynQor holds the following U.S. patents, one or more of which apply to
each product listed in this document. Additional patent applications may
be pending or led in the future.
5,999,417 6,222,742 6,545,890 6,577,109 6,594,159 6,731,520
6,894,468 6,896,526 6,927,987 7,050,309 7,072,190 7,085,146
7,119,524 7,269,034 7,272,021 7,272,023 7,558,083 7,564,702
7,765,687 7,787,261 8,023,290 8,149,597
Model Number Input
Voltage
Output
Voltage
Max Output
Current
SQ60120HZw50xyz 35-75V 12V 50A
Options Description:
Thermal Design Enable Logic Pin Style Feature Set
A - Open Frame
B - Baseplated
N - Negative
P - Positive
K - 0.110"
N - 0.145"
R - 0.180"
Y - 0.250"
S - Standard
