QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 1 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Applications
Telecommunications Telecommunications equipment
Data communications Data processing
Wireless communications Wireless base stations
Servers, Workstations LAN/WAN
Industrial applications
Benefits
Fully Voltage Regulated – for IBA
High efficiency– no heat sink
required
1
Baseplate option
Features
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
Description
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.
1 Baseplate/heat spreader option (suffix ‘-xxxBx’) facilitates heatsink mounting to further enhance the unit’s thermal capability.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 2 of 20
C
36-75 VDC Input; 12 VDC @ 35 A Output
Electrical Specifications
Conditions: TA = 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
Parameter
Notes
Min
Max
Units
Absolute Maximum Ratings
Input Voltage
Continuous
0
80
VDC
Transient (100ms)
100
VDC
Operating Temperature
(See Derating Curves)
Ambient (TA)
-40
85
°C
(Note: 1) Component (TC)
-40
125
°C
Baseplate (TB)
-40
105
°C
Storage Temperature
-55
125
°C
Isolation Characteristics
I/O Isolation (suffix ‘-xxx0x’)
[Input-to-Output]
1,500
VDC
Isolation Capacitance
pF
Isolation Resistance
10
MΩ
I/O Isolation (suffix ‘-xxxBx’)
[Input-to-Output & Baseplate-to-Input/Output]
1,500
VDC
Isolation Capacitance
[Input-to-Output]
pF
Isolation Resistance
[Input-to-Output & Baseplate-to-Input/Output]
10
MΩ
Feature Characteristics
Switching Frequency
kHz
Output Voltage Trim Range 2
%
Remote Sense Compensation 2
%
Output Overvoltage Protection
Non-latching
117
127
%
Overtemperature Shutdown (PCB)
Non-latching
°C
Auto-Restart Period
Applies to all protection features
ms
Turn-On Time including Rise Time
20,000µF plus Full Load (resistive)
30
ms
Rise Time
From 10% to 90%
25
ms
Turn-On Time from Vin
Time from UVLO to Vo=90%VOUT(NOM)
Resistive load
3
10
ms
Turn-On Time from ON/OFF Control
Time from ON to Vo=90%VOUT(NOM)
Resistive load
ms
Turn-On Time from Vin (w/ Cext max.)
Time from UVLO to Vo=90%VOUT(NOM)
Resistive load, CEXT=10,000µF load
5
25
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
ms
ON/OFF Control (Positive Logic)
Converter Off (logic low)
-20
0.8
VDC
Converter On (logic high)
2.4
20
VDC
ON/OFF Control (Negative Logic)
Converter Off (logic high)
2.4
20
VDC
Converter On (logic low)
-20
0.8
VDC
Additional Notes:
1. Reference Figure E for component (T
and TB) locations.
2. This functionality not provided, however the unit is fully regulated.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 3 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Electrical Specifications (continued)
Conditions: TA = 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
Parameter
Notes
Min
Typ
Max
Units
Input Characteristics
Operating Input Voltage Range
36
48
75
VDC
Input Under Voltage Lockout
Non-latching
Turn-on Threshold
31.5
34
35.5
VDC
Turn-off Threshold
30
33
34.5
VDC
Lockout Hysteresis Voltage
0.5
2
VDC
Input Voltage Transient Rate
7
V/ms
Maximum Input Current
35 ADC, 12 VDC Out @ 36 VDC In
12.3
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
0.1
A2s
Input Reflected-Ripple Current,
ic
25 MHz bandwidth, Io = 35 Amperes
(Figure 34)
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
12.24
VDC
Output Regulation 1
Over Line
Vin = 39 to 75VDC [IOUT = 35Amps]
±60
±120
mV
Over Load
±60
±120
mV
Output Voltage Range 1
2
Over line (39 to 75VDC), load and temp.
11.64
12.36
VDC
Over line (36 to 75VDC), load and temp.2
11.00
12.36
VDC
Output Ripple and Noise – 20 MHz bandwidth
IOUT = 35Amps,
CEXT =10 µF tantalum + 1 µF ceramic
100
150
mVPK-PK
60
mVrms
External Load Capacitance4
Full Load (resistive) C
EXT
ESR
0
1
20,000
µF
mΩ
Output Current Range
0
35
ADC
Current Limit Inception
Non-latching
110
143
%Iomax
Peak Short-Circuit Current 3
Non-latching, Short = 10 mΩ
55
70
A
RMS Short-Circuit Current
Non-latching
5
Arms
Dynamic Response
Load Change 50%-75%-50%, di/dt = 0.1A/µs
Co = 1 µF ceramic + 10µF tantalum
200
360
mV
di/dt = 1 A/µs
Co = 1 µF ceramic + 10µF tantalum
350
540
mV
Settling Time to 1% of VOUT
200
µs
Efficiency
100% Load
Vin = 39VDC
95
%
50% Load
Vin = 39VDC
96
%
Additional Notes:
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 See “Input & Output Impedance”, Page 5.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 4 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Environment and Mechanical Specifications
Environmental
Operating Humidity
Non-condensing
95
%
Storage Humidity
Non-condensing
95
%
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. 36)
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 5 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Operations
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.
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.
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 and
negative logic, with both referenced to Vin(-). A
typical connection is shown in Fig. A.
level voltage of 0.8 V. An external voltage source
(±20 V maximum) may be connected directly to the
ON/OFF input, 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.
Protection Features
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 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.
Output Overcurrent Protection (OCP)
Vin
CONTROL
INPUT
Vin (+)
ON/OFF
Vin (-)
QME Series
Converter
(Top View)
Vout (+)
Vout (-)
Rload
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.
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. 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
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.
Output Overvoltage Protection (OVP)
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 is removed.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 6 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
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 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.
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, Power-One 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 36 and 37 for
typical performance with external filter.
Absence of the Remote Sense Pins
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.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 7 of 20
OFF
ON
Scenario #1: Initial Startup From Bulk Supply
ON/OFF function enabled, converter started via application
of VIN. See Figure B.
Time
Comments
t0
ON/OFF pin is ON; system front end power is
toggled on, VIN to converter begins to rise.
t1
VIN crosses undervoltage 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.
Scenario #2: Initial Startup Using ON/OFF Pin
With VIN previously powered, converter started via
ON/OFF pin. See Figure C.
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.
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 D.
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 D.
t4
End of converter turn-on delay.
t5
Converter VOUT reaches 100% of nominal value.
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.
36-75 VDC Input; 12 VDC @ 35 A Output
V
IN
Startup Information (using negative ON/OFF)
ON/OFF
STATE
V
OUT
OFF
ON
t
t0 t1 t2
t
3
Fig. B: Startup scenario #1.
V
IN
ON/OFF
STATE
V
OUT
V
IN
t
t0 t1 t2 t3
Fig. C: Startup scenario #2.
ON/OFF
STATE OFF 200 ms
ON
V
OUT
t
0
t
1
t
2
t
t3 t4 t5
Fig. D: Startup scenario #3.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 8 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Characterization
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
mountings, efficiency, startup and shutdown
parameters, output ripple and noise, transient
response to load step-change, overload, and short
circuit.
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, 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
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. E)
(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. E)
(iii) The nominal rating of the converter (35 A).
Thermocouple (TB)
Area
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. E for the
optimum measuring thermocouple location.
Thermal Derating
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. 1, Fig. 3, Fig. 5 and Fig. 7.
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).
Thermocouples (TC)
Fig. E: Location of the thermocouples for thermal testing.
Output Power
The output power vs. ambient temperature and airflow
rates are given in Fig. 2 and Fig. 4 w/o baseplate. The
output power vs. ambient temperature and airflow
rates are given in Fig. 6 and Fig. 8 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).
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 9 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Thermal Derating – Baseplate Cooled
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 9. Power Derating is provided in Figure 10.
For a ¼” heatsink, AAvid Thermalloy PNU
241402B92200G, TC ≤ 125⁰C, current derating is provided
in Figure 11. Power Derating is provided in Figure 12.
For a ½” heatsink, AAvid Thermalloy PNU
241404B92200G, TC ≤ 120⁰C, current derating is provided
in Figure 13. Power Derating is provided in Figure 14.
For a ½” heatsink, AAvid Thermalloy PNU
241404B92200G, TC ≤ 125⁰C, current derating is provided
in Figure 15. Power Derating is provided in Figure 16.
For a 1” heatsink, AAvid Thermalloy PNU
241409B92200G, TC ≤ 120⁰C, current derating is provided
in Figure 17. Power Derating is provided in Figure 18.
For a 1” heatsink, AAvid Thermalloy PNU
241409B92200G, TC ≤ 125⁰C, current derating is provided
in Figure 19. Power Derating is provided in Figure 20.
Thermal Derating – Coldplate Cooled
The converter was shieled from air flow. The
baseplate temperature was maintained ≤ 85°C, with
an airflow rate of 30LFM ( 0.15m/s).
Thermocouple measurements (in Fig. E) were
recorded as TC ≤ 120°C and TB ≤ 85°C. Refer to
Figure 21 and Figure 22.
Efficiency
Efficiency vs. load current is showing in Fig. 23 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. 24.
Power Dissipation
Power dissipation vs. load current is showing in
Fig. 25 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. 26.
Startup
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. 27 and Fig. 28,
respectively.
Ripple and Noise
Fig. 31 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. 32. The
corresponding waveforms are shown in Fig. 33 and
Fig. 34.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 10 of 20
Load Current [Adc]
Load Current [Adc]
Output Power [W]
Output Power [W]
36-75 VDC Input; 12 VDC @ 35 A Output
Figures 1 & 2 without Baseplate, TC ≤ 120°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 1: 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.
Fig. 2: 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 3 & 4 with Baseplate, TC ≤ 120°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 3: 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.
Fig. 4: 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.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 11 of 20
Load Current [Adc]
Load Current [Adc]
Output Power W]
Output Power [W]
36-75 VDC Input; 12 VDC @ 35 A Output
Figures 5 & 6 without Baseplate, TC ≤ 125°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 5: 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 125C, Vin = 48 V.
Fig. 6: 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 125C, Vin = 48 V.
Figures 7 & 8 with Baseplate, TC ≤ 125°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 7: 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 125C, Vin = 48 V.
Fig. 8: 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 
125C, Vin = 48 V.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 12 of 20
Load Current [Adc]
Load Current [Adc]
Output Power [W]
Output Power [W]
36-75 VDC Input; 12 VDC @ 35 A Output
Figures 9 & 10 with ¼” Finned Heatsink, TC ≤ 120°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 9: 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.
Fig. 10: 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 11 & 12 th ¼” Finned Heatsink, TC ≤ 125°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
450
400
350
300
250
200
150
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
100
50
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 11: 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.
Fig. 12: 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, ¼” Heatsink.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 13 of 20
Load Current [Adc]
Load Current [Adc]
Output Power [W]
Output Power [W]
36-75 VDC Input; 12 VDC @ 35 A Output
Figures 13 & 14 with ½” Finned Heatsink, TC ≤ 120°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 13: 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 120C,
Vin = 48 V, ½” Heatsink.
Fig. 14: 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.
Figures 15 & 16 with ½” Finned Heatsink, TC ≤ 125°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 15: 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.
Fig. 16: 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.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 14 of 20
Output Power [W]
Load Current [Adc]
Output Power [W]
Output Power [W]
36-75 VDC Input; 12 VDC @ 35 A Output
Figures 17& 18 with 1” Finned Heatsink, TC ≤ 120°C
450
450
400
400
350
350
300
300
250
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 17: 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.
Fig. 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, 1” Heatsink.
Figures 19 & 20 with 1” Finned Heatsink, TC ≤ 125°C
40
35
30
25
20
500 LFM (2.5 m/s)
15 400 LFM (2.0 m/s)
450
400
350
300
250
200
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
10
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
5
150
100
50
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
0
20 30 40 50 60 70 80
90
Ambient Temperature [°C]
Fig. 19: 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.
Fig. 20: 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.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 15 of 20
C
Power Dissipation
[W]
Load Current [Adc]
Efficiency
Power Dissipation
[W]
Output Power [W]
Efficiency
36-75 VDC Input; 12 VDC @ 35 A Output
Figures 21 & 22 Coldplate Cooling, T ≤ 120°C
40 450
35 400
30 350
300
25 250
20 200
15 150
10 100
5 50
0 20 30 40 50 60 70 80 90 100 110
Baseplate Temperature [°C]
0 20 30 40 50 60 70 80 90 100 110
Baseplate Temperature [°C]
Fig. 21: 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.
Fig. 22: 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.
1.00
1.00
0.95 0.95
0.90 0.90
0.85
0.80
75 V
48 V
36 V
0.85
0.80
70 C
55 C
40 C
0.75
0 5 10 15 20 25 30 35 40
Load Current [Adc]
0.75
0 5 10 15 20 25 30 35 40
Load Current [Adc]
Fig. 23: 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.
Fig. 24: Efficiency 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).
30.00 35.00
25.00 30.00
20.00
15.00
10.00
5.00
75 V
48 V
36 V
25.00
20.00
15.00
10.00
5.00
70 C
55 C
40 C
0.00
0 5 10 15 20 25 30 35 40 0.00
0 5 10 15 20 25 30 35 40
Load Current [Adc]
Fig. 25: 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.
Load Current [Adc]
Fig. 26: 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).
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 16 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Fig. 27: 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.
Fig. 28: 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.
Fig. 29: 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.
Fig. 30: 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.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 17 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
iS iC
5 H
source
inductance
Vsource
33 F
ESR < 1
electrolytic
capacitor
QME 48
DC-DC
Converter
1 F
Ceramic
+ 10 F
Tantalum
Capacitor
Vout
Fig. 31: 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.
Fig. 32: Test setup for measuring input reflected ripple
currents, ic and is.
Fig. 33: Input reflected ripple current, ic (500 mA/div.),
measured at input terminals at full rated load current
and Vin = 48 V. Refer to Fig. 32 for test setup. Time
scale: 2 µs/div.
Fig. 34: 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. 32 for test setup.
Time scale: 2 µs/div.
Fig. 35: Load current (top trace, 20 A/div.,
100 ms/div.) into a 10 mΩ 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.
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 18 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
C 4
C 7
L
1
L
2
UUT
V
in
C 1
C 2
C 3
C 6
R lo
a
d
C 5
C 8
Comp. Des.
Description
C1, C2, C3,
2 x 1uF, 100V Ceramic Capacitor
C4, C5, C7, C8
4700pF Ceramic Capacitor
C6
100uF, 100V Electrolytic Capacitor
L1, L2
0.59mH, P0469NL Pulse Eng. Or,
equiv
Fig. 36: Typical input EMI filter circuit to attenuate conducted emissions.
Fig. 37: Input conducted emissions measurement (Typ.) of QME48T35120 with input filter shown in Figure 36.
Conditions: VIN=48VDC, IOUT = 35AMPS
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 19 of 20
Pad/Pin Connections
Pad/Pin #
Function
1
VIN (+)
2
ON/OFF
3
VIN (-)
4
VOUT (-)
5
VOUT (+)
Pin
Option
Pin Length
[PL]
±0.005” [±0.13]
A
0.188” [4.78]
B
0.145” [3.68]
C
0.110” [2.79]
36-75 VDC Input; 12 VDC @ 35 A Output
Physical Information
QME48T35120 Pinout (Through-hole)
PINS 1,2,3 Ø 0.040±0.002 [Ø 1.02±0.05 ]
WITH Ø 0.076 [1.93] SHOULDER
0.430 [10.92]
1.450±0.010 [36.83±0.25]
0.300 [7.62] 2X
2.300±0.010 [58.42±0.25]
2.000 [50.80]
0.145 [3.68]
1 5
PIN ASSIGNMENTS
2 AND LOCATIONS
PINS 4,5 Ø 0.062±0.002 [Ø 1.57±0.05 ]
WITH Ø 0.096 [2.44] SHOULDER
0.600 [15.24]
3 4
TOP VIEW
HT (-xJx0x)
PL
HT (-xJxBx)
SIDE VIEW
NO HEAT SPREADER
CL
CUSTOMER PCB
SIDE VIEW HEAT
SPREADER VERSION
CL
QME48T35120 Platform Notes
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 are Ø 0.096” [2.44] shoulder
Pin Material: Brass Alloy 360
Pin Finish: Tin over Nickel
Heatsink Mounting Screw: 3 in lb
maximum torque
PL
CUSTOMER PCB
Height
[HT]
Min
Clearance
[CL]
Special
Features
J
0.430” [10.4]
Max
0.028”
[0.71]
0
0.500” +/-0.020
[12.70 +/-0.51]
0.028”
[0.71]
B
Baseplate (Heat Spreader) Interface Information
PIN 1
MARK
0.210
[5.33]
2.300
±0.010
[58.42
±0.25
]
1.860
[47.24]
1.450±0.010 [36.83±0.25] TOP
VIEW
HEAT
SPREADER
PIN 1
MARK
1.030
[26.16]
INTERFACE
0.220
[5.59]
M3 X .5
2X
LIMIT SCREW
PENETRATION
TO LESS THAN 0.060
[1.52]
QME48T35120 DC-DC Converter
Rev 0.2c, 18-May-11
www.power-one.com
Page 20 of 20
36-75 VDC Input; 12 VDC @ 35 A Output
Converter Part Numbering Ordering Information
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
T
Through-
hole
35 A
120 12 V
N 
Negative
P 
Positive
J 
0.430”
for
–xJx0x
0.520”
for
–xJxBx
Through
hole
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 0.430”, 0.145” pin length, and standard (no baseplate). RoHS compliant for all 6 substances. Consult factory for
availability of other options.
Notes:
1. NUCLEAR AND MEDICAL APPLICATIONS - Power-One products are not designed, intended for use in, or authorized for use as critical
components in life support systems, equipment used in hazardous environments, or nuclear control systems without the express written
consent of the respective divisional president of Power-One, Inc.
2. 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.