The new high performance 35A QME48T35120 DC-DC converter provides a
high efficiency single output, in a 1/4 brick package. Specifically designed for
operation in systems that have limited airflow and increased ambient
temperatures, the QME48T35120 converter utilizes the same pin-out and
Input/Output functionality of the industry-standard quarter-bricks. In addition,
a baseplate feature is available (-xxxBx suffix) that provides an effective
thermal interface for coldplate and heat sinking options.
The QME48T35120 converter thermal performance is accomplished through
the use of patent-pending circuits, packaging, and processing techniques to
achieve ultra-high efficiency, excellent thermal management, and a 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
electronic circuits and thermal design, results in a product with extremely high
reliability.
Operating from a wide-range 36-75V input, the QME48T35120 converter
provides a fully regulated 12.0V output voltage. Employing a standard power
pin-out, the QME48T35120 converter is an ideal drop-in replacement for
existing high current quarter-brick designs. Inclusion of this converter in a new
design can result in significant board space and cost savings. The designer
can expect reliability improvement over other available converters because of
the QME48T35120 optimized thermal efficiency.
RoHS lead-free solder and lead-solder-exempted products are
available
Delivers up to 35 A (420 Watts)
Industry-standard quarter-brick pinout
On-board input differential LC-filter
Startup into pre-biased load
No minimum load required
Meets Basic Insulation requirements of EN60950-1
Withstands 100 V input transient for 100 ms
Fixed frequency operation
Fully protected (OTP, OCP, OVP, UVLO) with automatic recovery
Positive or negative logic ON/OFF option
Low height of 0.430” (10.4mm)
Weight: 1.75 oz (49.6g), 2.15 oz (61.0g) w/baseplate
High reliability: MTBF approx. 18.8 million hours, calculated per
Telcordia TR-332, Method I Case 1
Approved to the following Safety Standards: UL/CSA60950-1,
EN60950-1, and IEC60950-1
Designed to meet Class B conducted emissions per FCC and EN55022
when used 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.
PARAMETER
CONDITIONS / DESCRIPTION
MIN
TYP
UNITS
Absolute Maximum Ratings
Input Voltage
Continuous
0
VDC
Input Transient Voltage
100 ms
VDC
Operating Ambient Temperature (TA)
-40
°C
Operating Component Temperature (TC)
-40
°C
Operating Baseplate Temperature (TB)
-40
°C
Storage Temperature
-55
°C
Input Characteristics
Operating Input Voltage Range
36
48
VDC
Input Under Voltage Lockout
Non-latching
Turn-on Threshold
31.5
34
VDC
Turn-off Threshold
30
33
VDC
Lockout Hysteresis Voltage
0.5
VDC
Input Voltage Transient Rate
V/ms
Maximum Input Current
35 ADC, 12 VDC Out @ 36 VDC In
ADC
Input Stand-by Current
converter disabled
10
mADC
Input Current @ No Load
converter enabled
95
mADC
Minimum Input Capacitance (external)
ESR < 0.7 Ω
150
µF
Inrush Transient
A2S
Input Reflected-Ripple Current, ic
25 MHz bandwidth, Io = 35 Amperes
(Figure 39)
1250
mAPK-PK
Input Reflected-Ripple Current, iS
100
mAPK-PK
Input Voltage Ripple Rejection
120 Hz
45
dB
Output Characteristics
Output Voltage Set Point (no load)1
11.76
12.00
VDC
Output Regulation1
Over Line
Vin = 39 to 75VDC [IOUT = 35Amps]
±60
mV
Over Load
±60
mV
Output Voltage Range1
Over line (39 to 75VDC), load and temp.2
11.64
VDC
Over line (36 to 75VDC), load and temp.2
11.00
VDC
Output Ripple and Noise – 20 MHz bandwidth
IOUT = 35Amps
100
mVPK-PK
CEXT =10 µF tantalum + 1 µF ceramic
mVrms
External Load Capacitance
Full Load (resistive) CEXT
0
µF
ESR
1.000
mΩ
Output Current Range
ADC
Current Limit Inception
Non-latching
110
%Iomax
Peak Short-Circuit Current3
Non-latching, Short = 10 mΩ
55
A
RMS Short-Circuit Current
Non-latching
5
Arms
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Isolation Characteristics
I/O Isolation (suffix ‘ –xxx0x’)
Input-to-Output
1.500
VDC
Isolation Capacitance
1300
ρF
Isolation Resistance
10
MΩ
I/O Isolation (suffix ‘ –xxxBx’)
Input-to-Output & Baseplate-to-Input/Output
1.500
VDC
Isolation Capacitance
Input-to-Output
1300
ρF
Isolation Resistance
Input-to-Output & Baseplate-to-Input/Output
10
MΩ
Feature Characteristics
Switching Frequency
250
kHz
Output Voltage Trim Range4
n/a
%
Remote Sense Compensation4
n/a
%
Output Overvoltage Protection
Non-latching
117
122
%
Over-Temperature Shutdown (PCB)
Non-latching
130
°C
Auto-Restart Period
Applies to all protection features
200
ms
Turn-On Time including Rise Time
20,000µF plus Full Load (resistive)
15
ms
Rise Time
From 10% to 90%
13
ms
Turn-On Time from Vin
Time from UVLO to Vo=90%VOUT(NOM)
Resistive load
3
5
ms
Turn-On Time from ON/OFF Control
Time from UVLO to Vo=90%VOUT(NOM)
Resistive load
12
ms
Turn-On Time from Vin (w/Cext max.)
Time from UVLO to Vo=90%VOUT(NOM)
Resistive load, CEXT=10,000µF load
5
10
ms
Turn-On Time from ON/OFF Control (w/Cext
max.)
Time from ON to Vo=90%VOUT(NOM)
Resistive load, CEXT=10,000µF load
14
ms
ON/OFF Control (Positive Logic)
Converter Off (logic low)
-20
VDC
Converter On (logic high)
2.4
VDC
ON/OFF Control (Negative Logic)
Converter Off (logic low)
2.4
VDC
Converter On (logic high)
-20
VDC
Dynamic Response
Load Change 50%-75%-50%, di/dt = 0.1A/μs
Co = 1 μF ceramic + 10μF tantalum
200
mV
di/dt = 1.0 A/μs
Co = 1 μF ceramic + 10μF tantalum
350
mV
Settling Time to 1% of VOUT
200
μs
Efficiency
100% Load
Vin = 39VDC
95
%
50% Load
Vin = 39VDC
96
%
Environmental
Operating Humidity
Non-condensing
%
Storage Humidity
Non-condensing
%
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Mechanical
Weight
No baseplate
1.75 [49.6]
oz [g]
With baseplate
2.15 [61.0]
Vibration
GR-63-CORE, Sect. 5.4.2
1
g
Shocks
Half Sinewave, 3-axis
50
g
Reliability
MTBF
Telcordia SR-332, Method I Case 1
50% electrical stress, 40°C components
18.8
MHrs
EMI and Regulatory Compliance
Conducted Emissions
CISPR 22 B with external EMI filter network (See Fig. 41)
1) Measured at the output pins of the converter.
2) Operating ambient temperature range of -40 ºC to 85 ºC for converter.
3) Peak currents exist for approximately 500uSec per 200msec period.
4) This functionality not provided, however the unit is fully regulated.
These power converters have been designed to be stable with no external capacitors when used in low inductance input
and output circuits.
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 150 µF electrolytic capacitor with an ESR < 0.7 Ω across the input
helps to 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 20,000 µF.
Additionally, see the EMC section of this data sheet for discussion of other external components which may be required for
control of conducted emissions.
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 and negative logic, with both referenced to Vin(-). A typical connection is shown in Fig. 1.
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. See the Electrical Specifications for logic high/low definitions.
The negative logic version turns on when the ON/OFF pin is at logic low and turns off when the ON/OFF pin is at logic high.
The ON/OFF pin can be hardwired directly to Vin(-) to enable automatic power up of the converter without the need of an
external control signal.
The ON/OFF pin is internally pulled up to 5 V through a resistor. A properly debounced 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 0.2mA at
a low
in which case it must be capable of sourcing or sinking up to 1mA depending on the signal polarity. See the Startup
Information section for system timing waveforms associated with use of the ON/OFF pin.
The converter’s output overvoltage protection (OVP) senses the voltage across Vout(+) and Vout(-), 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 function.
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Input under-voltage 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 typically 34 V for the converter to turn on. Once the converter has been turned on, it will shut off
when the input voltage drops typically below 33 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 approx. 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 200 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.
Once the output current is brought back into its specified range, the converter automatically exits the hiccup mode and
continues normal operation.
The converter will shut down if the output voltage across Vout(+) (Pin 5) 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 200 ms until the OVP condition I removed.
The converter will shut down under an over temperature 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 are safety approved to UL/CSA60950-1, EN60950-1, and IEC60950-1. Basic Insulation is provided between
input and output.
The converters have no internal fuse. To comply with safety agencies requirements, an input line fuse must be used external
to the converter. A 20-A fuse is recommended for use with this product.
The QME48T35120 converter is CSA approved for a maximum fuse rating of 20A.
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, Power Bel 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.
An effective internal LC differential filter significantly reduces input reflected ripple current, and improves EMC.
With the addition of a simple external filter, the QME48T35120 converter will pass the requirements of Class B conducted
emissions per EN55022 and FCC requirements. Refer to Figures 41 and 42 for typical performance with external filter.
3.7
Users should note that this converter does not have a Remote Sense feature. Care should be taken to minimize voltage drop
on the user’s motherboard.
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Scenario #1: Initial Startup From Bulk Supply
ON/OFF function enabled, converter started via application of
VIN. See Figure 2.
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 8 ms.
Figure 2. Start-up scenario #1.
Scenario #2: Initial Startup Using ON/OFF Pin
With VIN previously powered, converter started via ON/OFF pin.
See Figure 3.
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 8 ms.
Figure 3. 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 4.
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 (200 ms typical) is
initiated, and ON/OFF pin action is internally inhibited.
t2
ON/OFF pin is externally re-enabled.
If (t2- t1) ≤ 200 ms, external action of ON/OFF
pin is locked out by startup inhibit timer.
If (t2- t1) > 200 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 4.
t4
End of converter turn-on delay.
t5
Converter VOUT reaches 100% of nominal value.
Figure 4. Startup scenario #3.
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For the condition, (t2- t1) ≤ 200 ms, the total converter startup time
(t5- t2) is typically 208 ms. For (t2- t1) > 200 ms, startup will be
typically 8 ms after release of ON/OFF pin.
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 mountings, efficiency, startup and shutdown
parameters, output ripple and noise, transient response to load step-change, overload, and short circuit.
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, comprised of two-ounce copper,
were used to provide traces for connectivity to the converter.
The lack of metallization 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 the vertical and horizontal wind tunnel 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. The use of AWG #36 gauge thermocouples is recommended to ensure measurement accuracy.
Careful routing of the thermocouple leads will further minimize measurement error. Refer to Fig. 5 for the optimum measuring
thermocouple location.
Thermal characterization is provided for the hotspot temperatures of both 120°C and 125°C.
Load current vs. ambient temperature and airflow rates are shown in Fig. 6, Fig. 8, Fig. 10 and Fig. 12. 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:
Case I : TC (Hotspot) ≤ 120°C
(i) The output current at which any FET junction (TJ) temperature does not exceed a maximum temperature of 120°C as
indicated by the thermal measurement, or
(ii) The output current at which the temperature at the thermocouple locations TC do not exceed 120°C. (Fig. 5)
(iii) The nominal rating of the converter (35 A).
Case II : TC (Hotspot) ≤ 125°C
(i) The output current at which any FET junction (TJ) temperature does not exceed a maximum temperature of 125°C as
indicated by the thermal measurement, or
(ii) The output current at which the temperature at the thermocouple locations TC do not exceed 125°C. (Fig. 5)
(iii) The nominal rating of the converter (35 A).
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Figure 5. Location of the thermocouples for thermal testing
4.4
The output power vs. ambient temperature and airflow rates are given in Fig. 7 and Fig. 9 w/o baseplate. The output power
vs. ambient temperature and airflow rates are given in Fig. 11 and Fig. 13 with baseplate. The ambient temperature varies
between 25°C and 85°C with airflow rates from 30 to 500 LFM (0.15 to 2.5 m/s).
The maximum load current rating vs. baseplate temperature is provided for Baseplate Models with commercially available
heatsinks attached. The various configurations, TC-MAX(Hotspot) and Figure references, are listed below.
Note: TC Hotspot ≈ TJ MOSFET
For a ¼” heatsink, AAvid Thermalloy PNU 241402B92200G, TC ≤ 120⁰C, current derating is provided in Figure 14. Power
Derating is provided in Figure 15.
For a ¼” heatsink, AAvid Thermalloy PNU 241402B92200G, TC ≤ 125⁰C, current derating is provided in Figure 16. Power
Derating is provided in Figure 17.
For a ½” heatsink, AAvid Thermalloy PNU 241404B92200G, TC ≤ 120⁰C, current derating is provided in Figure 18. Power
Derating is provided in Figure 19.
For a ½” heatsink, AAvid Thermalloy PNU 241404B92200G, TC ≤ 125⁰C, current derating is provided in Figure 20. Power
Derating is provided in Figure 21.
For a 1” heatsink, AAvid Thermalloy PNU 241409B92200G, TC ≤ 120⁰C, current derating is provided in Figure 22. Power
Derating is provided in Figure 23.
For a 1” heatsink, AAvid Thermalloy PNU 241409B92200G, TC ≤ 125⁰C, current derating is provided in Figure 24. Power
Derating is provided in Figure 25.
The converter was shielded from air flow. The baseplate temperature was maintained ≤ 85°C, with an airflow rate of ≥ 30LFM
(≥ 0.15m/s). Thermocouple measurements (in Fig. 5) were recorded as TC ≤ 120°C and TB ≤ 85°C. Refer to Figure 26 and
Figure 27.
Efficiency vs. load current is showing in Fig. 28 for ambient temperature (TA) of 25ºC, airflow rate of 300LFM (1.5m/s) with
vertical mounting and input voltages of 36V, 48V, and 75V. Also, a plot of efficiency vs. load current, as a function of ambient
temperature with Vin = 48V, airflow rate of 200 LFM (1 m/s) with vertical mounting is shown in Fig. 29.
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4.8
Power dissipation vs. load current is showing in Fig. 30 for TA = 25ºC, airflow rate of 300LFM (1.5m/s) with vertical mounting
and input voltages of 36V, 48V, and 75V. Also, a plot of power dissipation vs. load current, as a function of ambient
temperature with Vin = 48V, airflow rate of 200 LFM (1m/s) with vertical mounting is shown in Fig. 31.
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. 30 and Fig. 33, respectively.
Fig. 36 show 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 µF ceramic capacitor.
The input reflected ripple current waveforms are obtained using the test setup shown in Fig. 37. The corresponding
waveforms are shown in Fig. 38 and Fig. 39.
Figures 6 & 7 without Baseplate, TC 120 C.
Figure 6. Available output current vs. ambient air temperature
and airflow rates for converter w/o baseplate mounted
vertically with air flowing from pin 1 to pin 3, MOSFET
temperature 120 C., Vin = 48 V.
Figure 7. Available output power vs. ambient air temperature
and airflow rates for converter w/o baseplate mounted
vertically with air flowing from pin 1 to pin 3, MOSFET
temperature 120 C., Vin = 48 V.
Figures 8 & 9 with Baseplate, TC 120 C.
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Figure 8. Available output current vs. ambient air temperature
and airflow rates for converter with baseplate mounted
vertically with air flowing from pin 1 to pin 3, MOSFET
temperature 120 C., Vin = 48 V.
Figure 9. Available output power vs. ambient air temperature
and airflow rates for converter with baseplate mounted
vertically with air flowing from pin 1 to pin 3, MOSFET
temperature 120 C , Vin = 48 V.
Figures 10 & 11 without Baseplate, TC 125 C.
Figure 10. Available output current vs. ambient air
temperature and airflow rates for converter w/o baseplate
mounted vertically with air flowing from pin 1 to pin 3,
MOSFET temperature 125 C , Vin = 48 V.
Figure 11. Available output power vs. ambient air temperature
and airflow rates for converter w/o baseplate mounted
vertically with air flowing from pin 1 to pin 3, MOSFET
temperature 125 C , Vin = 48 V.
Figures 12 & 13 with Baseplate, TC 125 C.
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Figure 12. Available output current vs. ambient air
temperature and airflow rates for converter with baseplate
mounted vertically with air flowing from pin 1 to pin 3,
125 C, Vin = 48 V.
Figure 13. Available output power vs. ambient air temperature
and airflow rates for converter with baseplate vertically with air
flowing from pin 1 to pin 3, MOSFET temperature 125 C ,
Vin = 48 V.
Figures 14 & 15 with ¼“ Finned Heatsink, TC 120 C.
Figure 14. Available output current vs. ambient air temperature
and airflow rates for converter mounted vertically with air flowing
from pin 1 to pin 3, MOSFET temperature 120 C , Vin = 48 V,
¼” Heatsink.
Figure 15. Available output power vs. ambient air temperature and
airflow rates for converter mounted vertically with air flowing from
pin 1 to pin 3, MOSFET temperature 120 C , Vin = 48 V, ¼”
Heatsink.
Figures 16 & 17 with ¼“ Finned Heatsink, TC 125 C.
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Figure 16. Available output current vs. ambient air
temperature and airflow rates for converter mounted vertically
with air flowing from pin 1 to pin 3, MOSFET temperature
125 C , Vin = 48 V, ¼” Heatsink.
Figure 17. Available output power vs. ambient air temperature
and airflow rates for converter mounted vertically air flowing
from pin 1 to pin 3, MOSFET temperature 125 C , Vin = 48
V, ¼” Heatsink.
Figures 18 & 19 with ½“ Finned Heatsink, TC 120 C.
Figure 18. Available output current vs. ambient air
temperature and airflow rates for converter mounted vertically
with air flowing from pin 1 to pin 3, MOSFET temperature
120 C , Vin = 48 V, ½” Heatsink.
Figure 19. Available output power vs. ambient air temperature
and airflow rates for converter mounted vertically with air
flowing from pin 1 to pin 3, MOSFET temperature 120 C ,
Vin = 48 V, ½” Heatsink.
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Figures 20 & 21 with ½“ Finned Heatsink, TC 125 C.
Figure 20. Available output current vs. ambient air
temperature and airflow rates for converter mounted vertically
with air flowing from pin 1 to pin 3, MOSFET temperature
125 C , Vin = 48 V, ½” Heatsink.
Figure 21. Available output power vs. ambient air temperature
and airflow rates for converter mounted vertically with air
flowing from pin 1 to pin 3, MOSFET temperature 125 C ,
Vin = 48 V, ½” Heatsink.
Figures 22 & 23 with 1“ Finned Heatsink, TC 120 C.
Figure 22. Available output current vs. ambient air
temperature and airflow rates for converter mounted vertically
with air flowing from pin 1 to pin 3, MOSFET temperature
120 C , Vin = 48 V, 1” Heatsink.
Figure 23. Available output current vs. ambient air
temperature and airflow rates for converter mounted vertically
with air flowing from pin 1 to pin 3, MOSFET temperature
120 C , Vin = 48 V, 1” Heatsink.
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Figures 24 & 25 with 1“ Finned Heatsink, TC 125 C.
Figure 24. Available output current vs. ambient air
temperature and airflow rates for converter mounted vertically
with air flowing from pin 1 to pin 3, MOSFET temperature
125 C , Vin = 48 V, 1” Heatsink.
Figure 25. Available output power vs. ambient air temperature
and airflow rates for converter mounted vertically with air
flowing from pin 1 to pin 3, MOSFET temperature 125 C ,
Vin = 48 V, 1” Heatsink.
Figures 26 & 27 Coldplate Cooling TC 120 C.
Figure 26. Current derating of QME48T35120 converter with
baseplate option and coldplate cooling. (Conditions: Air
velocity
≥
30LFM (
≥
0.15m/s), Vin = 48 V, TB
≤
85°C, TC
≤
120
°C. No thermal derating required.
Figure 27. Power derating of QME48T35120 converter with
baseplate option and coldplate cooling. (Conditions: Air
velocity
≥
30LFM (
≥
0.15m/s), Vin = 48 V, TB
≤
85°C, TC
≤
120°C. No thermal derating required.
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Figure 28. Efficiency vs. load current and input voltage for
converter w/o baseplate mounted vertically with air flowing
from pin 3 to pin 1 at a rate of 300 LFM (1.5 m/s) and Ta=25°C.
Figure 29. Efficiency vs. load current and ambient temperature
for converter w/o baseplate mounted vertically with Vin=48V
and air flowing from pin 3 to pin 1 at a rate of 200 LFM
(1.0m/s).
Figure 30. Power dissipation vs. load current and input voltage for
converter w/o baseplate mounted vertically with air flowing from
pin 3 to pin 1 at a rate of 300 LFM (1.5 m/s) and Ta = 25 °C.
Figure 31. Power dissipation vs. load current and ambient
temperature for converter w/o baseplate 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 32. 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 (5 V/div.). Time scale: 5 ms/div.
Figure 33. Turn-on transient at full rated load current (resistive)
plus 20,000 µF at Vin = 48 V, triggered via ON/OFF pin. Top
trace: ON/OFF signal (5 V/div.). Bottom trace: output voltage (5
V/div.). Time scale: 5 ms/div
16
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Figure 34. Output voltage response to load current step-
change (17.5 A – 26.25 A – 17.5 A) at Vin = 48 V. Top trace:
output voltage (100 mV/div.). Bottom trace: load current (10
A/div.). Current slew rate: 0.1 A/µs. Co = 1 µF ceramic + 10 µF
tantalum. Time scale: 200 µs/div.
Figure 35. Output voltage response to load current step-
change (17.5 A – 26.25 A – 17.5 A) at Vin = 48 V. Top trace:
output voltage (200 mV/div.). Bottom trace: load current (10
A/div.). Current slew rate: 1 A/µs. Co = 1 µF ceramic + 10 µF
tantalum. Time scale: 200 µs/div.
Figure 36. Output voltage ripple (20 mV/div.) at full rated load
current into a resistive load with Co = 10 µF tantalum + 1 µF
ceramic and Vin = 48 V. Time scale: 2 µs/div.
Figure 37. Test setup for measuring input reflected ripple
currents, ic and is.
Figure 38. Input reflected ripple current, ic (500 mA/div.),
measured at input terminals at full rated load current and Vin =
48 V. Refer to Fig. 37 for test setup. Time scale: 2 µs/div.
Figure 39. Input reflected ripple current, is (50 mA/div.),
measured through 5 µH at the source at full rated load current
and Vin = 48 V. Refer to Fig. 37 for test setup. Time scale: 2
µs/div.
QME48T35120
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Europe, Middle East
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North America
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© 2016 Bel Power Solutions & Protection
BCD.00771_AB
Figure 40. Load current (top trace, 20 A/div., 100 ms/div) into
a 10 m
Ω
short circuit during restart, at Vin = 48 V. Bottom
trace (20 A/div., 100 ms/div.) is an expansion of the on-time
portion of the top trace.
18
QME48T35120
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Figure 42. Input conducted emissions measurement (Typ.) of QME48T35120 with input filter shown in Figure 41. Conditions:
VIN=48VDC, IOUT = 35AMPS
Figure 41. Typical input EMI filter circuit to attenuate conducted emissions.
COMPONENT DESCRIPTION
DECSRIPTION
C1, C2, C3
2 x 1uF, 100 V Ceramic Capacitor
C4, C5, C7, C8
4700pF Ceramic Capacitor
C6
100uF, 100 V Electrolytic Capacitor
L1, L2
0.59mH, P0469NL Pulse Eng. Or, equiv
QME48T35120
19
Asia-Pacific
+86 755 298 85888
Europe, Middle East
+353 61 225 977
North America
+1 408 785 5200
© 2016 Bel Power Solutions & Protection
BCD.00771_AB
Height
HT
(Minimum
Clearance
CL
Special
Features
Pin
Option
Pin Length PL
±0.005
[±0.13]
J
0.430” [10.4] Max
0.028” [0.71]
0
A
0.188 [4.78]
0.500” +/- 0.020
[12.70 +/- 0.51]
0.028” [0.71]
B
B
0.145 [3.68]
C
0.110 [2.79]
• All dimensions are in inches [mm]
• Pins 1 – 3 are Ø 0.040” [1.02] with
Ø 0.076” [1.93] shoulder
• Pins 4 and 5 are Ø 0.062” [1.57]
with Ø 0.096” [2.44] shoulder
• Pin Material: Brass Alloy 360
• Pin Finish: Tin over Nickel
• Heatsink Mounting Screw: 3 in lb
maximum torque
PAD/PIN CONNECTIONS
Pad/Pin #
Function
1
Vin (+)
2
ON/OFF
3
Vin (-)
4
Vout (-)
5
Vout (+)
20
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Product
Series
Input
Voltage
Mounting
Scheme
Rated
Load
Current
Output
Voltage
ON/OFF
Logic
Maximum
Height [HT]
Pin
Length [PL]
Special
Features
RoHS
QME
48
T
35
120
-
N
J
B
0
G
Quarter-
Brick
Format
36-75 V
Trough
hole
35 A
120 12 V
N
Negative
P
Positive
J 0.430”
for – xJx0x
J 0.520”
for – xJxBx
A 0.188”
B 0.145”
C 0.110”
0 STD
B Baseplate
option
No Suffix
RoHS
lead-solder-
exemption
compliant
G RoHS
compliant
for all six
substances
The example above describes P/N QME48T35120-NJB0G: 36-75 V input, through-hole mounting, 35 A @ 12 V output, negative ON/OFF logic, a
maximum height of 0.520”, 0.145” pin length, with baseplate.. RoHS compliant for all 6 substances. Consult factory for availability of other options.
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.