The QM Series of high current single output dc-dc converters sets new
standards for thermal performance and power density in the quarter-brick
package.
The QM48T/S25050 converters of the QM Series provide thermal performance
in high temperature environments that is comparable to or exceeds the
industry’s leading 5 V half-bricks. This is accomplished through the use of
patent pending circuit, packaging and processing techniques to achieve ultra-
high efficiency, excellent thermal management, and a very low body profile.
Low body profile and the preclusion of heat sinks minimize impedance to
system airflow, thus enhancing cooling for both upstream and downstream
devices. The use of 100% automation for assembly, coupled with advanced
electric and thermal design, results in a product with extremely high reliability.
Operating from a 36-75 V input, the QM Series converters provide outputs that
can be trimmed from –20% to +10% of the nominal output voltage, thus
providing outstanding design flexibility.
• RoHS lead-free solder and lead-solder-exempted products are available
• Delivers up to 25 A @ 5.0 V
• Industry-standard quarter brick pinout
• On-board input differential LC-filter
• High efficiency – no heat sink required
• Start-up into pre-biased output
• No minimum load required
• Available in through-hole and surface-mount packages
• Low profile: 0.28” [7.1 mm] SMT version,
• 0.31” [7.9 mm] TH version
• Low weight: 1.1 oz [31.5 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
• UL60950 recognized in US and Canada and
• Approved to the following Safety Standards: UL/CSA60950-1, EN60950-1,
and IEC60950-1
• Meets conducted emissions requirements of FCC Class B and EN 55022
Class B with external filter
• All materials meet UL94, V-0 flammability rating
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Conditions: TA = 25ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
CONDITIONS / DESCRIPTION
MIN
TYP
MAX
UNITS
Continuous
0
80
VDC
-40
85
°C
-55
125
°C
36
48
75
VDC
Non-latching
33
34
35
VDC
31
32
33
VDC
100 ms
100
VDC
25 ADC, 5 VDC Out @ 36 VDC In
3.9
ADC
Vin = 48 V, converter disabled
2.65
mADC
Vin = 48 V, converter enabled
52
mADC
25 MHz bandwidth
12.5
mAPK-PK
120 Hz
TBD
dB
Plus full load (resistive)
10,000
μF
0
25
ADC
Non-latching
27.5
30
34.5
ADC
Non-latching. Short = 10 mΩ.
31
50
A
Non-latching
6.5
Arms
4.950
5.000
5.050
VDC
±2
±5
mV
±2
±5
mV
Over line, load and temperature2
4.925
5.075
VDC
Full load + 10 μF tantalum + 1 μF ceramic
30
50
mVPK-PK
2000
VDC
1.4
nF
10
MΩ
340
kHz
Industry-std. equations
-20
+10
%
Percent of VOUT(nom)
+10
%
Non-latching
117
128
140
%
Applies to all protection features
100
ms
4
ms
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BCD.00631_AB3
-20
0.8
VDC
2.4
20
VDC
2.4
20
VDC
-20
0.8
VDC
Co = 470 μF tantalum + 1 μF ceramic
120
mV
40
µs
89.5
%
90.5
%
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
2.1
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
2,200 µF on 5 V output.
2.2
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. 1.
Rload
Vin
CONTROL
INPUT
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
(Top View)
Converter
QmaXTM Series
Figure 1. 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.
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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.
2.3
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. 2).
100
10
Rw
Rw
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
(Top View)
Converter
QmaXTM Series
Figure 2. 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 ensure 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 overvoltage 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.
2.4
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.
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. 3. 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 −
−+
=−
−
[kΩ]
where,
RT-INCR = Required value of trim-up resistor k]
VO-NOM = Nominal value of output voltage [V]
100X
V)V(V
ΔNOM- O
NOM-OREQ-O −
=
[%]
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Vo-REQ = 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.
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
RT-INCR
(Top View)
Converter
SeriesQmaXTM
Figure 3. Configuration for increasing output voltage.
To decrease the output voltage (Fig. 4), 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 −=−
[kΩ]
where,
RT-DECR 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. More information can be found in Output Voltage Trim Feature Application Note.
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-) RT-DECR
(Top View)
Converter
Series
QmaXTM
QmaXQmaXTM
Figure 4. 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 overvoltage 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 0.50 V, or:
SENSESENSEOUTOUT 0.50)](V)([V)](V)([V −−+−−−+
[V]
This equation is applicable for any condition of output sensing and/or output trim.
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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.
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 60% 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 3% duty cycle. The
attempted restart will continue indefinitely until the overload or short circuit conditions are removed or the output voltage
rises above 60% of its nominal value.
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.
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.
The converters meet North American and International safety regulatory requirements per UL60950 and EN60950. 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 fuse with rating
of 7A is recommended for use with this product.
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 their 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 QM 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 Solution Applications Engineering for details of this testing.
Figure 5. Location of the thermocouple for thermal testing
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Scenario #1: Initial Startup From Bulk Supply
ON/OFF function enabled, converter started via application of
VIN. See Figure 6.
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 startup time (t3- t1) is
typically 4 ms.
Figure 6. Start-up scenario #1.
Scenario #2: Initial Startup Using ON/OFF Pin
With VIN previously powered, converter started via ON/OFF pin.
See Figure 7.
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 startup time (t3- t1) is
typically 4 ms.
Figure 7. Startup 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 8.
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 startup 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 7.
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 startup
time (t5- t2) is typically 104 ms. For (t2- t1) > 100 ms, startup will be
typically 4 ms after release of ON/OFF pin.
Figure 8. Startup 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
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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.
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 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.
Load current vs. ambient temperature and airflow rates are given in Figs. 9-12 for vertical and horizontal converter mounting
both through-hole and surface mount version. 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 (25 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. 13 should not exceed 118 °C in order to
operate inside the derating curves.
4.4
Fig.13 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. 14.
Fig. 15 shows the power dissipation vs. load current plot for Ta = 25ºC, 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. 16.
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. 17 and Fig. 18, respectively.
Figure 20 shows the output voltage ripple waveform, measured at full rated load current with a 10 µF tantalum and 1 µF
ceramic capacitor across the output. Note that all output voltage waveforms are measured across a 1 F ceramic capacitor.
The input reflected ripple current waveforms are obtained using the test setup shown in Fig 21. The corresponding
waveforms are shown in Figs. 22 and 23.
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Ambient Temperature [°C]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
5
10
15
20
25
30
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)
Figure 9. Available load current vs. ambient air temperature and
airflow rates for QM48T25050 converter with B height pins
mounted vertically with air flowing from pin 3 to pin 1, MOSFET
temperature 120 Cº, Vin = 48 V.
Ambient Temperature [°C]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
5
10
15
20
25
30
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)
Figure 10. Available load current vs. ambient air temperature and
airflow rates for QM48T25050 converter with B height pins
mounted horizontally 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
5
10
15
20
25
30
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)
Figure 11. Available load current vs. ambient temperature and
airflow rates for QM48S25050 converter mounted vertically with
Vin = 48 V, air flowing from pin 3 to pin 1 and maximum FET
temperature 120C.
Ambient Temperature [°C]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
5
10
15
20
25
30
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)
Figure 12. Available load current vs. ambient temperature and
airflow rates for QM48S25050 converter mounted horizontally with
Vin = 48 V, air flowing from pin 3 to pin 1 and maximum FET
temperature 120C.
Load Current [Adc]
0 5 10 15 20 25 30
Efficiency
0.65
0.70
0.75
0.80
0.85
0.90
0.95
72 V
48 V
36 V
Figure 13. 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]
0 5 10 15 20 25 30
Efficiency
0.65
0.70
0.75
0.80
0.85
0.90
0.95
70 C
55 C
40 C
Figure 14. 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).
10
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Load Current [Adc]
0 5 10 15 20 25 30
Power Dissipation [W]
0.00
4.00
8.00
12.00
16.00
20.00
72 V
48 V
36 V
Figure 15. 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]
0 5 10 15 20 25 30
Power Dissipation [W]
0.00
4.00
8.00
12.00
16.00
20.00
70 C
55 C
40 C
Figure 16. 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).
Figure 17
.
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 (2 V/div.) Time scale: 2 ms/div.
Figure 18. Turn-on transient at full rated load current
(resistive) plus 10,000 F at Vin = 48 V, triggered via
ON/OFF pin. Top trace: ON/OFF signal (5 V/div.). Bottom
trace: output voltage (2 V/div.). Time scale: 2 ms/div.
Figure 19. Output voltage response to load current step-
change (12.5 A – 18.75 A – 12.5 A) at Vin = 48 V. Top trace:
output voltage (100 mV/div.). Bottom trace: load current (5
A/div). Current slew rate: 1 A/s. Co = 470 F tantalum + 1 F
ceramic. Time scale: 0.2 ms/div.
Figure 20. 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.
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BCD.00631_AB3
Vout
Vsource
iSiC
1 F
ceramic
capacitor
10 H
source
inductance DC/DC
Converter
33 F
ESR <1
electrolytic
capacitor
QmaXSeries
QmaXTM
Figure 21. Test setup for measuring input reflected ripple currents, ic and is.
Figure 22. 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. 21 for test setup. Time
scale: 1s/div.
Figure 23. Input reflected ripple current, ic (200 mA/div),
measured at input terminals at full rated load current and
Vin = 48 V. Refer to Fig. 21 for test setup. Time scale: 1
s/div.
Figure 24. Output voltage vs. load current showing current
limit point and converter shutdown point. Input voltage has
almost no effect on current limit characteristic.
Figure 25. 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.
1.0
20 30 40
6.0
Iout [Adc]
Vout [Vdc]
0
0
3.0
5.0
10
4.0
2.0
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• All dimensions are in inches [mm]
• Connector Material: Copper
• Connector Finish: Gold over Nickel
• Converter Weight: 1.1oz [31.5 g]
• Recommended Surface-Mount Pads:
Min. 0.080” X 0.112” [2.03 x 2.84]
Max. 0.092” X 0.124” [2.34 x 3.15]
PAD/PIN CONNECTIONS
Pad/Pin #
Function
1
Vin (+)
2
ON/OFF
3
Vin (-)
4
Vout (-)
5
SENSE (-)
6
TRIM
7
SENSE (+)
8
Vout (+)
QM48T (Through-Hole)
• 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 or
Matte Tin over Nickel for “G” version
• Converter Weight: 1.1 oz [31.5 g] typical
Height
Option
HT
(Maximum
Height)
CL
(Minimum
Clearance)
A
0.325 [8.26]
0.030 [0.77]
B
0.358 [9.09]
0.063 [1.60]
D
0.422 [10.72]
0.127 [3.23]
Pin
Option
PL
(Pin Length)
±0.005 [±0.13]
A
0.188 [4.77]
B
0.145 [3.68]
C
0.110 [2.79]
QM48T25050/ QM48S25050
13
Asia-Pacific
+86 755 298 85888
Europe, Middle East
+353 61 225 977
North America
+1 408 785 5200
© 2020 Bel Power Solutions & Protection
BCD.00631_AB3
Product
Series
Input
Voltage
Mountin
g
Scheme
Rated Load
Current
Output
Voltage
ON/OFF
Logic
Maximum
Height [HT]
Pin
Length [PL]
Special
Features
RoHS
QM
48
T
25
050
-
N
B
A
0
Quarter-
Brick
Format
36-75 V
S
Surface
Mount
T
Through
Hole
25 ADC
050 5.0 V
N
Negative
P
Positive
SMT
S 0.295”
Through hole
A 0.325”
B 0.358”
D 0.422”
SMT
0 0.00”
Through hole
A 0.188”
B 0.145”
C 0.110”
0 STD
No Suffix
RoHS
lead-solder-
exemption
compliant
G RoHS
compliant
for all six
substances
The example above describes P/N QM48T25050-NBA0: 36-75 V input, through-hole, 25 A @ 5 V output, negative ON/OFF logic, a maximum height
of 0.358”, a through the board pin length of 0.188”, and RoHS lead-solder-exemption compliancy. Please consult factory regarding availability of a
specific version.
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.