© 2015 Bel Power Solutions, Inc.
North America
+1-866.513.2839
Asia-Pacific
+86.755.29885888
Europe, Middle East
+353 61 225 977
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BCD.00632_AA
RoHS lead-free solder and lead-solder-exempted
products are available
Delivers up to 40 A (132 W)
Industry-standard quarter brick pinout
Higher current capability at 70ºC than most
competitors’ 40 A half-bricks
On-board input differential LC-filter
High efficiency – no heat sink required
Start-up into pre-biased output
No minimum load required
Low profile: 0.31” [7.9 mm]
Low weight: 1.06 oz [30 g] typical
Meets Basic Insulation requirements of EN60950
Withstands 100 V input transient for 100 ms
Fixed-frequency operation
Fully protected
Remote output sense
Output voltage trim range: +10%/−20% with Industry-
standard trim equations
High reliability: MTBF of 2.6 million hours, calculated
per Telcordia TR-332, Method I Case 1
Positive or negative logic ON/OFF option
UL 60950 recognition in US and Canada and DEMKO
certification per IEC/EN 60950
Meets conducted emissions requirements of FCC
Class B and EN 55022 Class B with external filter
All materials meet UL94, V-0 flammability rating
The QmaXTM Series of high current single output DC-DC
converters from Bel Power Solutions sets new standards for
thermal performance and power density in the quarter brick
pack-age.
The 40A QM48T converters of the QmaXTM Series provide
thermal performance in high temperature environments that
is comparable to or exceeds the industry’s leading 40A
halfbricks. This is accomplished through the use of patent
pending circuit, packaging and processing techniques to
achieve ultra-high efficiency, excellent thermal manage-
ment and a very low body profile.
The QM48T40 converters have a power density of up to 130
W/in3, more than twice that of competitors’ 40A halfbricks.
Over 1 square inch of board space can be saved for every
slot in which a 40A half-brick is replaced with a QM48T40
converter from Bel Power Solutions.
Low body profile and the preclusion of heat sinks minimize
impedance to system airflow, thus enhancing cooling for
downstream devices. The use of 100% automation for
assembly, coupled with Bel Power Solutions advanced
electric and thermal design, results in a product with
extremely high reliability.
Operating from a 36-75 V input, the QmaXTM Series
converters provide standard output voltage for 3.3 V.
Output can be trimmed from –20% to +10% of the nominal
output voltage, thus providing outstanding design flexibility.
QM48T40033
© 2015 Bel Power Solutions, Inc.
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BCD.00632_AA
Conditions: TA = 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
PARAMETER
NOTES
TYP
MAX
UNITS
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Continuous
80
VDC
Operating Ambient Temperature
85
°C
Storage Temperature
125
°C
INPUT CHARACTERISTICS
Operating Input Voltage Range
48
75
VDC
Input Under Voltage Lockout
Non-latching
Turn-on Threshold
34
35
VDC
Turn-off Threshold
32
33
VDC
Input Voltage Transient
100 ms
100
VDC
ISOLATION CHARACTERISTICS
I/O Isolation
VDC
Isolation Capacitance
1.4
nF
Isolation Resistance
MΩ
FEATURE CHARACTERISTICS
Switching Frequency
415
kHz
Output Voltage Trim Range1
Industry-std. equations on page 5
+10
%
Remote Sense Compensation1
Percent of VOUT(NOM)
+10
%
Output Over-Voltage Protection
Non-latching
128
140
%
Auto-Restart Period
Applies to all protection features
100
ms
Turn-On Time
4
ms
ON/OFF Control (Positive Logic)
Converter Off
0.8
VDC
Converter On
20
VDC
ON/OFF Control (Negative Logic)
Converter Off
20
VDC
Converter On
0.8
VDC
INPUT CHARACTERISTICS
Maximum Input Current
40 ADC, 3.3 VDC Out @ 36 VDC In
4.1
ADC
Input Stand-by Current
Vin = 48 V, converter disabled
3
mADC
Input No Load Current (0 load on the output)
Vin = 48 V, converter enabled
63
mADC
Input Reflected-Ripple Current
25MHz bandwidth
7.5
mAPK-PK
Input Voltage Ripple Rejection
120Hz
64
dB
OUTPUT CHARACTERISTICS
Output Voltage Set Point (no load)
3.300
3.333
VDC
Output Regulation
Over Line
±2
±5
mV
Over Load
±2
±5
mV
Output Voltage Range
Over line, load and temperature2
3.350
VDC
Output Ripple and Noise - 25MHz bandwidth
Full load + 10 μF tantalum + 1 μF ceramic
30
50
mVPK-PK
External Load Capacitance
Plus full load (resistive)
40,000
μF
Output Current Range
40
ADC
Current Limit Inception
Non-latching
47
52
ADC
Peak Short-Circuit Current
Non-latching. Short=10mΩ.
50
60
A
RMS Short-Circuit Current
Non-latching
10
15
Arms
DYNAMIC RESPONSE
Load Change 25% of Iout Max, di/dt = 1 A/μS
Co = 470 μF tantalum + 1 μF ceramic
120
mV
Setting Time to 1%
80
µs
QM48T40033
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BCD.00632_AA
EFFICIENCY
100% Load
90.5
%
50% Load
92.5
%
Additional Notes:
1 Vout can be increased up to 10% via the sense leads or up to 10% via the trim function, however total output voltage trim
from all sources should not exceed 10% of VOUT (NOM), in order to insure specified operation of over-voltage protection circuitry.
2 -40ºC to 85ºC
Input and Output Impedance
These power converters have been designed to be stable with no external capacitors when used in low inductance input and
output circuits.
However, in many applications, the inductance associated with the distribution from the power source to the input of the
converter can affect the stability of the converter. The addition of a 33 µF electrolytic capacitor with an ESR < 1 across the
input helps ensure stability of the converter. In many applications, the user has to use decoupling capacitance at the load.
The power converter will exhibit stable operation with external load capacitance up to 40,000 µF.
ON/OFF (Pin 2)
The ON/OFF pin is used to turn the power converter on or off remotely via a system signal. There are two remote control
options available, positive logic and negative logic and both are referenced to Vin(-). Typical connections are shown in Fig.
A.
Rload
Vin
CONTROL
INPUT
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
(Top View)
Converter
QmaXTM Series
Fig. A: Circuit configuration for ON/OFF function.
The positive logic version turns on when the ON/OFF pin is at logic high and turns off when at logic low. The converter is on
when the ON/OFF pin is left open.
The negative logic version turns on when the pin is at logic low and turns off when the pin is at logic high. The ON/OFF pin
can be hard wired directly to Vin(-) to enable automatic power up of the converter without the need of an external control
signal.
ON/OFF pin is internally pulled-up to 5 V through a resistor. A mechanical switch, open collector transistor, or FET can be
used to drive the input of the ON/OFF pin. The device must be capable of sinking up to 0.2 mA at a low level voltage of 0.8
V. An external voltage source of ±20 V max. may be connected directly to the ON/OFF input, in which case it should be
capable of sourcing or sinking up to 1 mA depending on the signal polarity. See the Start-up Information section for system
timing waveforms associated with use of the ON/OFF pin.
Remote Sense (Pins 5 and 7)
The remote sense feature of the converter compensates for voltage drops occurring between the output pins of the converter
and the load. The SENSE(-) (Pin 5) and SENSE(+) (Pin 7) pins should be connected at the load or at the point where regulation
is required (see Fig. B).
QM48T40033
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BCD.00632_AA
100
10
Rw
Rw
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
(Top View)
Converter
QmaXTM Series
Fig. B: Remote sense circuit configuration.
If remote sensing is not required, the SENSE(-) pin must be connected to the Vout(-) pin (Pin 4), and the SENSE(+) pin must
be connected to the Vout(+) pin (Pin 8) to ensure the converter will regulate at the specified output voltage. If these
connections are not made, the converter will deliver an output voltage that is slightly higher than the specified value.
Because the sense leads carry minimal current, large traces on the end-user board are not required. However, sense traces
should be located close to a ground plane to minimize system noise and insure optimum performance. When wiring discretely,
twisted pair wires should be used to connect the sense lines to the load to reduce susceptibility to noise.
The converter’s output over-voltage protection (OVP) senses the voltage across Vout(+) and Vout(-), and not across the sense
lines, so the resistance (and resulting voltage drop) between the output pins of the converter and the load should be minimized
to prevent unwanted triggering of the OVP.
When utilizing the remote sense feature, care must be taken not to exceed the maximum allowable output power capability
of the converter, equal to the product of the nominal output voltage and the allowable output current for the given conditions.
When using remote sense, the output voltage at the converter can be increased by as much as 10% above the nominal rating
in order to maintain the required voltage across the load. Therefore, the designer must, if necessary, decrease the maximum
current (originally obtained from the derating curves) by the same percentage to ensure the converter’s actual output power
remains at or below the maximum allowable output power.
Output Voltage Adjust /TRIM (Pin 6)
The output voltage can be adjusted up 10% or down 20% relative to the rated output voltage by the addition of an externally
connected resistor. Trim up to 10% is guaranteed only at Vin ≥ 40 V, and it is marginal (8% to 10%) at Vin = 36 V.
The TRIM pin should be left open if trimming is not being used. To minimize noise pickup, a 0.1 µF capacitor is connected
internally between the TRIM and SENSE(-) pins.
To increase the output voltage, refer to Fig. C. A trim resistor, RT-INCR, should be connected between the TRIM (Pin 6) and
SENSE(+) (Pin 7), with a value of:
10.22
1.225Δ
626Δ)V5.11(100
RNOMO
INCRT
[k]
where,
INCRTR
Required value of trim-up resistor k]
NOMOV
Nominal value of output voltage [V]
100X
V)V(V
Δ NOM- O
NOM-OREQ-O
[%]
REQOV
Desired (trimmed) output voltage [V].
When trimming up, care must be taken not to exceed the converter‘s maximum allowable output power. See previous
section for a complete discussion of this requirement.
QM48T40033
© 2015 Bel Power Solutions, Inc.
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BCD.00632_AA
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
RT-INCR
(Top View)
Converter
SeriesQmaXTM
Fig. C: Configuration for increasing output voltage.
To decrease the output voltage (Fig. D), a trim resistor, RT-DECR, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
10.22
|Δ|511
RDECRT
[k]
where,
DECRTR
Required value of trim-down resistor [k]
and
Δ
is as defined above.
Note: The above equations for calculation of trim resistor values match those typically used in conventional industry-standard
quarter bricks. For more information see Application Note 103.
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-) RT-DECR
(Top View)
Converter
Series
QmaXTM
QmaXQmaXTM
Fig. D: Configuration for decreasing output voltage.
Trimming/sensing beyond 110% of the rated output voltage is not an acceptable design practice, as this condition could
cause unwanted triggering of the output over-voltage protection (OVP) circuit. The designer should ensure that the difference
between the voltages across the converter’s output pins and its sense pins does not exceed 0.33 V, or:
0.33)](V)([V)](V)([V SENSESENSEOUTOUT
[V]
This equation is applicable for any condition of output sensing and/or output trim.
QM48T40033
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BCD.00632_AA
Input Undervoltage Lockout
Input undervoltage lockout is standard with this converter. The converter will shut down when the input voltage drops
below a pre-determined voltage.
The input voltage must be at least 35 V for the converter to turn on. Once the converter has been turned on, it will shut off
when the input voltage drops below 31 V. This feature is beneficial in preventing deep discharging of batteries used in
telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or short circuit conditions. Upon sensing an overcurrent condition, the
converter will switch to constant current operation and thereby begin to reduce output voltage. When the output voltage
drops below 50% of the nominal value of output voltage, the converter will shut down.
Once the converter has shut down, it will attempt to restart nominally every 100 ms with a typical 1-2% duty cycle. The
attempted restart will continue indefinitely until the overload or short circuit conditions are removed or the output voltage
rises above 50% of its nominal value.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage across Vout(+) (Pin 8) and Vout(-) (Pin 4) exceeds the threshold of the
OVP circuitry. The OVP circuitry contains its own reference, independent of the output voltage regulation loop. Once the
converter has shut down, it will attempt to restart every 100 ms until the OVP condition is removed.
Overtemperature Protection (OTP)
The converter will shut down under an overtemperature
condition to protect itself from overheating caused by
operation outside the thermal derating curves, or operation in abnormal conditions such as system fan failure. After the
converter has cooled to a safe operating temperature, it will automatically restart.
Safety Requirements
The converters meet North American and International safety regulatory requirements per UL60950 and EN60950 (pending).
Basic Insulation is provided between input and output.
To comply with safety agencies requirements, an input line fuse must be used external to the converter. A 7.5-A fuse is
recommended for use with this product.
Modules are UL approved for maximum fuse rating of 15-A. To protect a group of modules with a single fuse, the rating can
be increased from the recommended values above.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product system level, as no specific standards dedicated to EMC
characteristics of board mounted component dc-dc converters exist. However, Bel Power Solutions tests its converters to
several system level standards, primary of which is the more stringent EN55022,
Information technology equipment - Radio
disturbance characteristics - Limits and methods of measurement.
Effective internal LC differential filter significantly reduces input reflected ripple current, and improves EMC.
With the addition of a simple external filter, all versions of the QmaX™ Series of converters pass the requirements of Class
B conducted emissions per EN55022 and FCC, and meet at a minimum, Class A radiated emissions per EN 55022 and
Class B per FCC Title 47CFR, Part 15-J. Please contact Bel Power Solutions Applications Engineering for details of this
testing.
Fig. H: Location of the thermocouple for thermal testing.
QM48T40033
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BCD.00632_AA
General Information
The converter has been characterized for many operational aspects, to include thermal derating (maximum load current as
a function of ambient temperature and airflow) for vertical and horizontal mounting, efficiency, start-up and shutdown
parameters, output ripple and noise, transient response to load step-change, overload and short circuit.
The following pages contain specific plots or waveforms associated with the converter. Additional comments for specific
data are provided below.
Test Conditions
All data presented were taken with the converter soldered to a test board, specifically a 0.060” thick printed wiring board
(PWB) with four layers. The top and bottom layers were not metalized. The two inner layers, comprising two-ounce
copper, were used to provide traces for connectivity to the converter.
The lack of metalization on the outer layers as well as the limited thermal connection ensured that heat transfer from the
converter to the PWB was minimized. This provides a worst-case but consistent scenario for thermal derating purposes.
All measurements requiring airflow were made in Bel Power Solutions’s vertical and horizontal wind tunnel facilities using
Infrared (IR) thermography and thermocouples for
thermometry.
Ensuring components on the converter do not exceed their ratings is important to maintaining high reliability. If one
anticipates operating the converter at or close to the maximum loads specified in the derating curves, it is prudent to check
actual operating temperatures in the application. Thermographic imaging is preferable; if this capability is not available, then
thermocouples may be used. Bel Power Solutions recommends the use of AWG #40 gauge thermocouples to ensure
measurement accuracy. Careful routing of the thermocouple leads will further minimize measurement error. Refer to Figure
H for optimum measuring thermocouple location.
Thermal Derating
Load current vs. ambient temperature and airflow rates are given in Figs. 1 and 2 for vertical and horizontal converter
mounting. Ambient temperature was varied between 25 °C and 85 °C, with airflow rates from 30 to 500 LFM (0.15 to 2.5
m/s).
For each set of conditions, the maximum load current was defined as the lowest of:
(i) The output current at which either any FET junction temperature did not exceed a maximum specified temperature
(120 °C) as indicated by the thermographic image, or
(ii) The nominal rating of the converter (40 A).
During normal operation, derating curves with maximum FET temperature less than or equal to 120 °C should not be
exceeded. Temperature on the PCB at the thermocouple location shown in Fig. H should not exceed 118 °C in order to
operate inside the derating curves.
Efficiency
Fig. 3 shows the efficiency vs. load current plot for ambient temperature of 25 ºC, airflow rate of 300 LFM (1.5 m/s) with
vertical mounting and input voltages of 36 V, 48 V and 72 V. Also, a plot of efficiency vs. load current, as a function of
ambient temperature with Vin = 48 V, airflow rate of 200 LFM (1 m/s) with vertical mounting is shown in Fig. 4.
Power Dissipation
Fig. 5 shows the power dissipation vs. load current plot for Ta = 25 ºC, airflow rate of 300 LFM (1.5 m/s) with vertical
mounting and input voltages of 36 V, 48 V and 72 V. Also, a plot of power dissipation vs. load current, as a function of
ambient temperature with Vin = 48 V, airflow rate of 200 LFM (1 m/s) with vertical mounting is shown in Fig. 6.
Start-up
Output voltage waveforms, during the turn-on transient using the ON/OFF pin for full rated load currents (resistive load) are
shown without and with external load capacitance in Fig. 7 and Fig. 8, respectively.
Ripple and Noise
Fig. 10 shows the output voltage ripple waveform, measured at full rated load current with a 10µF tantalum and 1µF
ceramic capacitor across the output. Note that all output voltage waveforms are measured across a 1F ceramic capacitor.
The input reflected ripple current waveforms are obtained using the test setup shown in Fig. 11. The corresponding
waveforms are shown in Fig. 12 and Fig. 13.
QM48T40033
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BCD.00632_AA
Start-up Information (using negative ON/OFF)
Scenario #1: Initial Start-up From Bulk Supply
ON/OFF function enabled, converter started via
application of VIN. See Figure E.
Time
Comments
t0
ON/OFF pin is ON; system front end power
is toggled on, VIN to converter begins to
rise.
t1
VIN crosses Under-Voltage Lockout
protection circuit threshold; converter
enabled.
t2
Converter begins to respond to turn-on
command (converter turn-on delay).
t3
Converter VOUT reaches 100% of nominal
value.
For this example, the total converter start-up time (t3-
t1) is typically 4 ms.
Fig. E: Start-up scenario #1.
Scenario #2: Initial Start-up Using ON/OFF Pin
With VIN previously powered, converter started via
ON/OFF pin. See Figure F.
Time
Comments
t0
VINPUT at nominal value.
t1
Arbitrary time when ON/OFF pin is enabled
(converter enabled).
t2
End of converter turn-on delay.
t3
Converter VOUT reaches 100% of nominal
value.
For this example, the total converter start-up time (t3-
t1) is typically 4 ms.
Fig. F: Start-up scenario #2.
Scenario #3: Turn-off and Restart Using ON/OFF Pin
With VIN previously powered, converter is disabled and then
enabled via ON/OFF pin. See Figure G.
Time
Comments
t0
VIN and VOUT are at nominal values; ON/OFF pin ON.
t1
ON/OFF pin arbitrarily disabled; converter output falls to
zero; turn-on inhibit delay period (100 ms typical) is
initiated, and ON/OFF pin action is internally inhibited.
t2
ON/OFF pin is externally re-enabled.
If (t2- t1) ≤ 100 ms, external action of ON/OFF pin is
locked out by start-up inhibit timer.
If (t2- t1) > 100 ms, ON/OFF pin action is internally
enabled.
t3
Turn-on inhibit delay period ends. If ON/OFF pin is ON,
converter begins turn-on; if off, converter awaits ON/OFF
pin ON signal; see Figure F.
t4
End of converter turn-on delay.
t5
Converter VOUT reaches 100% of nominal value.
For the condition, (t2- t1) ≤ 100 ms, the total converter start-up time (t5-
t2) is typically 104 ms. For (t2- t1) > 100 ms, start-up will be typically 4
ms after release of ON/OFF pin.
Fig. G: Start-up scenario #3
VIN
ON/OFF
STATE
VOUT
t
t0t1t2t3
ON
OFF
ON/OFF
STATE
VOUT
t0t1t2t3
ON
OFF
VIN
t
ON/OFF
STATE OFF
ON
VOUT
t0t2t1t5
VIN
t
t4t3
100 ms
QM48T40033
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BCD.00632_AA
Ambient Temperature [°C]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
10
20
30
40
50
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
Fig. 1: Available load current vs. ambient air temperature
and airflow rates for QM48T40033 converter with B height
pins mounted vertically with air flowing from pin 3 to pin 1,
MOSFET temperature 120C, Vin = 48 V.
Ambient Temperature [°C]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
10
20
30
40
50
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
Fig. 2: Available load current vs. ambient air temperature
and airflow rates for QM48T40033 converter with B height
pins mounted horizontally with air flowing from pin 3 to pin
1, MOSFET temperature 120C, Vin = 48 V.
Load Current [Adc]
010 20 30 40 50
Efficiency
0.65
0.70
0.75
0.80
0.85
0.90
0.95
72 V
48 V
36 V
Fig. 3: Efficiency vs. load current and input voltage for
converter mounted vertically with air flowing from pin 3 to
pin 1 at a rate of 300 LFM (1.5 m/s) and Ta = 25C.
Load Current [Adc]
010 20 30 40 50
Efficiency
0.65
0.70
0.75
0.80
0.85
0.90
0.95
70 C
55 C
40 C
Fig. 4: Efficiency vs. load current and ambient temperature
for converter mounted vertically with Vin = 48 V and air
flowing from pin 3 to pin 1 at a rate of 200 LFM (1.0 m/s).
Load Current [Adc]
010 20 30 40 50
Power Dissipation [W]
0.00
4.00
8.00
12.00
16.00
72 V
48 V
36 V
Fig. 5: Power dissipation vs. load current and input voltage for
converter mounted vertically with air flowing from pin 3 to pin 1
at a rate of 300 LFM (1.5 m/s) and Ta = 25C.
Load Current [Adc]
010 20 30 40 50
Power Dissipation [W]
0.00
4.00
8.00
12.00
16.00
70 C
55 C
40 C
Fig. 6: Power dissipation vs. load current and ambient
temperature for converter mounted vertically with Vin = 48 V and
air flowing from pin 3 to pin 1 at a rate of 200 LFM (1.0 m/s).
QM48T40033
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BCD.00632_AA
Fig. 7: Turn-on transient at full rated load current (resistive)
with no output capacitor at Vin = 48 V, triggered via
ON/OFF pin. Top trace: ON/OFF signal (5 V/div.). Bottom
trace: output voltage (1 V/div.) Time scale: 2 ms/div.
Fig. 8: Turn-on transient at full rated load current (resistive)
plus 40,000 F at Vin = 48 V, triggered via ON/OFF pin.
Top trace: ON/OFF signal (5 V/div.). Bottom trace: output
voltage (1 V/div.). Time scale: 2 ms/div.
Fig. 9: Output voltage response to load current step-
change (20 A – 30 A – 20 A) at Vin = 48 V. Top trace: output
voltage (100 mV/div.). Bottom trace: load current (10 A/div).
Current slew rate: 1 A/s. Co = 470 F tantalum + 1 F
ceramic. Time scale: 0.2 ms/div.
Fig. 10: Output voltage ripple (20 mV/div.) at full rated load
current into a resistive load with Co = 10 F tantalum + 1uF
ceramic and Vin = 48 V. Time scale: 1 s/div.
Vout
Vsource
iSiC
1 F
ceramic
capacitor
10 H
source
inductance DC/DC
Converter
33 F
ESR <1
electrolytic
capacitor
QmaXSeries
QmaXTM
Fig. 11: Test setup for measuring input reflected ripple currents, ic and is.
QM48T40033
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BCD.00632_AA
Fig. 12: Input reflected ripple current, is (10 mA/div),
measured through 10 H at the source at full rated load
current and Vin = 48 V. Refer to Fig. 11 for test setup. Time
scale: 1s/div.
Fig. 13: Input reflected ripple current, ic (100 mA/div),
measured at input terminals at full rated load current and
Vin = 48 V. Refer to Fig. 11 for test setup. Time scale: 1
s/div.
Fig. 14: Output voltage vs. load current showing current
limit point and converter shutdown point. Input voltage has
almost no effect on current limit characteristic.
Fig. 15: Load current (top trace, 20 A/div, 20 ms/div) into a
10 m short circuit during restart, at Vin = 48 V. Bottom
trace (20 A/div, 1 ms/div) is an expansion of the on-time
portion of the top trace.
Product
Series
Input
Voltage
Mounting
Scheme
Rated Load
Current
Output
Voltage
ON/OFF
Logic
Maximum
Height (HT)
Pin
Length (PL)
Special
Features
QM
48
T
40
033
-
N
B
B
0
Quarter-
Brick
Format
36-75 V
Through-
hole
40 A
033 3.3 V
N Negative
P Positive
A 0.325”
B 0.358”
D 0.422”
A 0.188”
B 0.145”
C 0.110”
0 STD
The example above describes P/N QM48T40033-NBB0: 36-75 V input, through-hole mounting, 40 A @ 3.3 V output, negative ON/OFF logic, a
maximum height of 0.358”, and a through the board pin length of 0.145”. Please consult factory regarding availability of a specific version.
RoHS Ordering Information:
No RoHS suffix character is required for lead-solder-exemption compliance.
For RoHS compliance to all six substances, add the letter "G" as the last letter of the part number.
Iout [Adc]
15 60
4.0
Vout [Vdc]
0
0
2.0
1.0
30 45
3.0
NOTE: The QM48T40033 is not recommended for new designs.
QM48T40033
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866.513.2839
tech.support@psbel.com
BCD.00632_AA
NUCLEAR AND MEDICAL APPLICATIONS - Products are not designed or intended for use as critical components in life support
systems, equipment used in hazardous environments, or nuclear control systems.
TECHNICAL REVISIONS - The appearance of products, including safety agency certifications pictured on labels, may change depending
on the date manufactured. Specifications are subject to change without notice.
SIDE VIEW
TOP VIEW
1
2
3
7
8
6
5
4
Height
Option
HT
(Maximum Height)
CL
(Minimum Clearance)
Pin
Option
PL
(Pin Length)
+0.000 [+0.00]
-0.038 [-0.97]
+0.016 [+0.41]
-0.000 [-0.00]
±0.005 [±0.13]
A
0.325 [8.26]
0.030 [0.77]
A
0.188 [4.77]
B
0.358 [9.09]
0.063 [1.60]
B
0.145 [3.68]
D
0.422 [10.72]
0.127 [3.23]
C
0.110 [2.79]
All dimensions are in inches [mm]
Pins 1-3 and 5-7 are Ø 0.040” [1.02]
with Ø 0.078” [1.98] shoulder
Pins 4 and 8 are Ø 0.062” [1.57]
without shoulder
Pin Material: Brass
Pin Finish: Tin/Lead over Nickel
Converter Weight: 1.06 oz [30 g]
typical
PIN CONNECTIONS
Pin #
Function
1
Vin (+)
2
ON/OFF
3
Vin (-)
4
Vout (-)
5
SENSE(-)
6
TRIM
7
SENSE(+)
8
Vout (+)