QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
The QmaXTM Series of high current single output DC-DC
converters from Power-One sets new standards for thermal
performance and power density in the quarter brick package.
The 40A QM48S converters of the QmaXTM Series provide
thermal performance in high temperature environments that
is comparable to or exceeds the industry’s leading 40A half
bricks. This is accomplished through the use of patent pend-
ing circuit, packaging and processing techniques to achieve
ultra-high efficiency, excellent thermal management and a
very low body profile.
The QM48S40 converters have a power density of up to
130 W/in3, more than twice that of competitors’ 40A half
bricks. Over 1 square inch of board space can be saved for
every slot in which a 40A half brick is replaced with a
QM48S40 converter from Power-One.
Low body profile and the preclusion of heat sinks minimize
impedance to system airflow, thus enhancing cooling for
downstream devices. The use of 100% automation for as-
sembly, coupled with Power-One’s advanced electric and
thermal design, results in a product with extremely high reli-
ability.
Operating from a 36-75 V input, the QmaXTM Series con-
verters provide standard output voltage for 3.3 V. Output can
be trimmed from –20% to +10% of the nominal output volt-
age, thus providing outstanding design flexibility.
Applications
• Telecommunications
• Data communications
• Wireless
• Servers
QM48S40033 Converter
Features
• RoHS lead-free solder and lead-solder-exempted
products are available
• Delivers up to 40 A (132 W)
• Industry-standard SM quarter brick pinout
• Higher current capability at 70 ºC than most competi-
tors’ 40 A half bricks
• On-board input differential LC-filter
• High efficiency – no heat sink required
• Start up into pre-biased output
• No minimum load required
• Low profile: 0.28” [7.1 mm]
• Low weight: 1.06 oz [30 g] typical
• Meets Basic Insulation requirements of EN60950
• Withstands 100 V input transient for 100 ms
• Fixed-frequency operation
• Fully protected
• Remote output sense
• Output voltage trim range: +10%/20% with Industry-
standard trim equations
• High reliability: MTBF of 2.6 million hours, calculated
per Telcordia TR-332, Method I Case 1
• Positive or negative logic ON/OFF option
• UL 60950 recognition in US and Canada and DEMKO
certification per IEC/EN 60950
• Meets conducted emissions requirements of FCC
Class B and EN 55022 Class B with external filter
• All materials meet UL94, V-0 flammability rating
FEB 10, 2004 revised to NOV 13, 2006 Page 1 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Electrical Specifications
Conditions: TA=25ºC, Airflow=300 LFM (1.5 m/s), Vin=48 Vdc, unless otherwise specified.
PARAMETER NOTES MIN TYP MAX UNITS
ABSOLUTE MAXIMUM RATINGS
Input Voltage Continuous 0 80 Vdc
Operating Ambient Temperature -40 85 °C
Storage Temperature -55 125 °C
INPUT CHARACTERISTICS
Operating Input Voltage Range 36 48 75 Vdc
Input Under Voltage Lockout Non-latching
Turn-on Threshold 33 34 35 Vdc
Turn-off Threshold 31 32 33 Vdc
Input Voltage Transient 100 ms 100 Vdc
ISOLATION CHARACTERISTICS
I/O Isolation 2000 Vdc
Isolation Capacitance 1.4 nF
Isolation Resistance 10 M
FEATURE CHARACTERISTICS
Switching Frequency 415 kHz
Output Voltage Trim Range1 Industry-std. equations on page 4 -20 +10 %
Remote Sense Compensation1 Percent of VOUT(NOM) +10 %
Output Over-Voltage Protection Non-latching 117 128 140 %
Auto-Restart Period Applies to all protection features 100 ms
Turn-On Time 4 ms
ON/OFF Control (Positive Logic)
Converter Off -20 0.8 Vdc
Converter On 2.4 20 Vdc
ON/OFF Control (Negative Logic)
Converter Off 2.4 20 Vdc
Converter On -20 0.8 Vdc
Additional Notes:
1. Vout can be increased up to 10% via the sense leads or up to 10% via the trim function, however total output voltage trim from all sources
should not exceed 10% of VOUT(NOM), in order to insure specified operation of over-voltage protection circuitry.
FEB 10, 2004 revised to NOV 13, 2006 Page 2 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Electrical Specifications: (continued)
Conditions: TA=25ºC, Airflow=300 LFM (1.5 m/s), Vin=48 Vdc, unless otherwise specified.
PARAMETER NOTES MIN TYP MAX UNITS
INPUT CHARACTERISTICS
Maximum Input Current 40 Adc, 3.3 Vdc Out @ 36 Vdc In 4.1 Adc
Input Stand-by Current Vin = 48 V, converter disabled 3 mAdc
Input No Load Current (0 load on the output) Vin = 48 V, converter enabled 63 mAdc
Input Reflected-Ripple Current 25MHz bandwidth 7.5 mAPK-PK
Input Voltage Ripple Rejection 120Hz 64 dB
OUTPUT CHARACTERISTICS
Output Voltage Set Point (no load) 3.267 3.300 3.333 Vdc
Output Regulation
Over Line ±2 ±5 mV
Over Load ±2 ±5 mV
Output Voltage Range Over line, load and temperature2 3.250 3.350 Vdc
Output Ripple and Noise - 25MHz bandwidth Full load + 10 µF tantalum + 1 µF ceramic 30 50 mVPK-PK
External Load Capacitance Plus full load (resistive) 40,000 µF
Output Current Range 0 40 Adc
Current Limit Inception Non-latching 42 47 52 Adc
Peak Short-Circuit Current Non-latching. Short=10m. 50 60 A
RMS Short-Circuit Current Non-latching 10 15 Arms
DYNAMIC RESPONSE
Load Change 25% of Iout Max, di/dt = 1 A/µS Co = 470 µF tantalum + 1 µF ceramic 120 mV
Setting Time to 1% 80 µs
EFFICIENCY
100% Load 90.5 %
50% Load 92.5 %
Additional Notes:
2. -40ºC to 85ºC
FEB 10, 2004 revised to NOV 13, 2006 Page 3 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Operation
Input and Output Impedance
These power converters have been designed to be stable
with no external capacitors when used in low inductance in-
put 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 addi-
tion of a 33 µF electrolytic capacitor with an ESR < 1 Ω
across the input helps ensure stability of the converter. In
many applications, the user has to use decoupling capaci-
tance at the load. The power converter will exhibit stable op-
eration with external load capacitance up to 40,000 µF.
ON/OFF (Pin 2)
The ON/OFF pin is used to turn the power converter on or
off remotely via a system signal. There are two remote con-
trol options available, positive logic and negative logic and
both are referenced to Vin(-). Typical connections are shown
in Fig. A.
Rload
Vin
CONTROL
INPUT
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
(Top View)
Converter
QmaX
TM Series
Fig. A: Circuit configuration for ON/OFF function.
The positive logic version turns on when the ON/OFF pin is
at a logic high and turns off when at a logic low. The con-
verter is on when the ON/OFF pin is left open.
The negative logic version turns on when the pin is at a logic
low and turns off when the pin is at a logic high. The
ON/OFF pin can be hard wired directly to Vin(-) to enable
automatic power up of the converter without the need of an
external control signal.
ON/OFF pin is internally pulled-up to 5 V through a resistor.
A mechanical switch, open collector transistor, or FET can
be used to drive the input of the ON/OFF pin. The device
must be capable of sinking up to 0.2 mA at a low level volt-
age 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 1 mA
depending on the signal polarity. See the Start-up Informa-
tion section for system timing waveforms associated with
use of the ON/OFF pin.
Remote Sense (Pins 5 and 7)
The remote sense feature of the converter compensates for
voltage drops occurring between the output pins of the con-
verter and the load. The SENSE(-) (Pin 5) and SENSE(+)
(Pin 7) pins should be connected at the load or at the point
where regulation is required (see Fig. B).
100
10
Rw
Rw
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
(Top View)
Converter
QmaXTM
Series
Fig. B: Remote sense circuit configuration.
If remote sensing is not required, the SENSE(-) pin must be
connected to the Vout(-) pin (Pin 4), and the SENSE(+) pin
must be connected to the Vout(+) pin (Pin 8) to ensure the
converter will regulate at the specified output voltage. If
these connections are not made, the converter will deliver an
output voltage that is slightly higher than the specified value.
Because the sense leads carry minimal current, large traces
on the end-user board are not required. However, sense
traces should be located close to a ground plane to minimize
system noise and insure optimum performance. When wiring
discretely, twisted pair wires should be used to connect the
sense lines to the load to reduce susceptibility to noise.
The converter’s output over-voltage protection (OVP) senses
the voltage across Vout(+) and Vout(-), and not across the
sense lines, so the resistance (and resulting voltage drop)
between the output pins of the converter and the load should
be minimized to prevent unwanted triggering of the OVP.
When utilizing the remote sense feature, care must be taken
not to exceed the maximum allowable output power capabil-
ity of the converter, equal to the product of the nominal out-
put voltage and the allowable output current for the given
conditions.
FEB 10, 2004 revised to NOV 13, 2006 Page 4 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
When using remote sense, the output voltage at the con-
verter 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 con-
verter’s actual output power remains at or below the maxi-
mum allowable output power.
Output Voltage Adjust /TRIM (Pin 6)
The output voltage can be adjusted up 10% or down 20%
relative to the rated output voltage by the addition of an ex-
ternally connected resistor. Trim up to 10% is guaranteed
only at Vin 40 V, and it is marginal (8% to 10%) at Vin =
36 V.
The TRIM pin should be left open if trimming is not being
used. To minimize noise pickup, a 0.1 µF capacitor is con-
nected internally between the TRIM and SENSE(-) pins.
To increase the output voltage, refer to Fig. C. A trim resis-
tor, RT-INCR, should be connected between the TRIM (Pin 6)
and SENSE(+) (Pin 7), with a value of:
10.22
1.225∆
626∆)V5.11(100
RNOMO
INCRT −
−+
=−
− [kΩ]
where,
=−INCRTRRequired value of trim-up resistor kΩ]
=−NOMOVNominal value of output voltage [V]
100X
V
)V(V
∆
NOM- O
NOM-OREQ-O −
= [%]
=−REQOVDesired (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 (-)
R
T-INCR
(Top View)
Converter
Series
QmaXTM
Fig. C: Configuration for increasing output voltage.
To decrease the output voltage (Fig. D), a trim resistor,
RT-DECR, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
10.22
|∆|
511
RDECRT −=− [kΩ]
where,
=
−DECRTRRequired value of trim-down resistor [kΩ]
and
∆
is as defined above.
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industry-
standard quarter bricks. For more information see Applica-
tion Note 103.
Rload
Vin
Vin (+)
Vin (-)
ON/OFF
Vout (+)
Vout (-)
TRIM
SENSE (+)
SENSE (-)
R
T-DECR
(Top View)
Converter
Series
QmaXTM
QmaXQmaXTM
Fig. D: Configuration for decreasing output voltage.
Trimming/sensing beyond 110% of the rated output voltage
is not an acceptable design practice, as this condition could
cause unwanted triggering of the output over-voltage protec-
tion (OVP) circuit. The designer should ensure that the dif-
ference between the voltages across the converter’s output
pins and its sense pins does not exceed 0.33 V, or:
0.33)](V)([V)](V)([V SENSESENSEOUTOUT
≤
−−+
−
−
−
+
[V]
This equation is applicable for any condition of output sens-
ing and/or output trim.
FEB 10, 2004 revised to NOV 13, 2006 Page 5 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
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 34V for the converter to
turn on. Once the converter has been turned on, it will shut
off when the input voltage drops typically below 32V. This
feature is beneficial in preventing deep discharging of batter-
ies used in telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or short cir-
cuit conditions. Upon sensing an over-current condition, the
converter will switch to constant current operation and
thereby begin to reduce output voltage. When the output
voltage drops below 50% of the nominal value of output volt-
age, the converter will shut down.
Once the converter has shut down, it will attempt to restart
nominally every 100 ms with a typical 1-2% duty cycle. The
attempted restart will continue indefinitely until the overload
or short circuit conditions are removed or the output voltage
rises above 50% of its nominal value.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage across
Vout(+) (Pin 8) and Vout(-) (Pin 4) exceeds the threshold of
the OVP circuitry. The OVP circuitry contains its own refer-
ence, independent of the output voltage regulation loop.
Once the converter has shut down, it will attempt to restart
every 100 ms until the OVP condition is removed.
Overtemperature Protection (OTP)
The converter will shut down under an overtemperature con-
dition to protect itself from overheating caused by operation
outside the thermal derating curves, or operation in abnor-
mal conditions such as system fan failure. After the con-
verter has cooled to a safe operating temperature, it will
automatically restart.
Safety Requirements
The converters meet North American and International
safety regulatory requirements per UL60950 and EN60950.
Basic Insulation is provided between input and output.
To comply with safety agencies requirements, an input line
fuse must be used external to the converter. A 7.5-A fuse is
recommended for use with this product.
Modules are UL approved for maximum fuse rating of 15-A.
To protect a group of modules with a single fuse, the rating
can be increased from the recommended values above.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product system
level, as no specific standards dedicated to EMC character-
istics 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 distur-
bance characteristics - Limits and methods of measurement.
Effective internal LC differential filter significantly reduces
input reflected ripple current, and improves EMC.
With the addition of a simple external filter, all versions of the
QmaX™ Series of converters pass the requirements of
Class B conducted emissions per EN55022 and FCC, and
meet at a minimum, Class A radiated emissions per EN
55022 and Class B per FCC Title 47CFR, Part 15-J. Please
contact Power-One Applications Engineering for details of
this testing.
Fig. H: Location of the thermocouple for thermal testing.
FEB 10, 2004 revised to NOV 13, 2006 Page 6 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
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 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 as-
sociated with the converter. Additional comments for specific
data are provided below.
Test Conditions
All data presented were taken with the converter soldered to
a test board, specifically a 0.060” thick printed wiring board
(PWB) with four layers. The top and bottom layers were not
metalized. The two inner layers, comprising two-ounce cop-
per, were used to provide traces for connectivity to the con-
verter.
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 pur-
poses.
All measurements requiring airflow were made in Power-
One’s vertical and horizontal wind tunnel facilities using In-
frared (IR) thermography and thermocouples for thermome-
try.
Ensuring components on the converter do not exceed their
ratings is important to maintaining high reliability. If one an-
ticipates 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. Thermo-
graphic imaging is preferable; if this capability is not avail-
able, then thermocouples may be used. Power-One recom-
mends the use of AWG #40 gauge thermocouples to ensure
measurement accuracy. Careful routing of the thermocouple
leads will further minimize measurement error. Refer to Fig-
ure H for optimum measuring thermocouple location.
Thermal Derating
Load current vs. ambient temperature and airflow rates are
given in Figs. 1 and 2 for vertical and horizontal converter
mounting. Ambient temperature was varied between 25°C
and 85°C, with airflow rates from 30 to 500 LFM (0.15 to 2.5
m/s).
For each set of conditions, the maximum load current was
defined as the lowest of:
(i) The output current at which any FET junction temperature
does not exceed a maximum specified temperature (120°C)
as indicated by the thermographic image, or
(ii) The nominal rating of the converter (40 A).
During normal operation, derating curves with maximum FET
temperature less than or equal to 120°C should not be ex-
ceeded. Temperature on the PCB at the thermocouple loca-
tion shown in Fig. H should not exceed 118°C in order to
operate inside the derating curves.
Efficiency
Fig. 3 shows the efficiency vs. load current plot for ambient
temperature of 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 efficiency vs. load current, as a function of
ambient temperature with Vin = 48 V, airflow rate of 200 LFM
(1 m/s) with vertical mounting is shown in Fig. 4.
Power Dissipation
Fig. 5 shows the power dissipation vs. load current plot for
Ta = 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. 6.
Start-up
Output voltage waveforms, during the turn-on transient using
the ON/OFF pin for full rated load currents (resistive load)
are shown without and with external load capacitance in
Fig. 7 and Fig. 8, respectively.
Ripple and Noise
Fig. 10 shows the output voltage ripple waveform, measured
at full rated load current with a 10 µF tantalum and 1 µF ce-
ramic capacitor across the output. Note that all output volt-
age waveforms are measured across a 1 µF ceramic capaci-
tor.
The input reflected ripple current waveforms are obtained
using the test setup shown in Fig. 11. The corresponding
waveforms are shown in Fig. 12 and Fig. 13.
FEB 10, 2004 revised to NOV 13, 2006 Page 7 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Start-up Information (using negative ON/OFF)
Scenario #1: Initial Start-up From Bulk Supply
ON/OFF function enabled, converter started via application of VIN.
See Figure E.
Time Comments
t0ON/OFF pin is ON; system front end power is toggled
on, VIN to converter begins to rise.
t1VIN crosses Under-Voltage Lockout protection circuit
threshold; converter enabled.
t2Converter begins to respond to turn-on command (con-
verter turn-on delay).
t3Converter VOUT reaches 100% of nominal value.
For this example, the total converter start-up time (t3- t1) is typically
4 ms.
Fig. E: Start-up scenario #1.
VIN
ON/OFF
STATE
VOUT
t
t0t1t2t3
ON
OFF
Scenario #2: Initial Start-up Using ON/OFF Pin
With VIN previously powered, converter started via ON/OFF pin.
See Figure F.
Time Comments
t0VINPUT at nominal value.
t1Arbitrary time when ON/OFF pin is enabled (converter
enabled).
t2End of converter turn-on delay.
t3Converter VOUT reaches 100% of nominal value.
For this example, the total converter start-up time (t3- t1) is typically
4 ms.
Scenario #3: Turn-off and Restart Using ON/OFF Pin
With VIN previously powered, converter is disabled and then en-
abled via ON/OFF pin. See Figure G.
Time Comments
t0VIN and VOUT are at nominal values; ON/OFF pin ON.
t1ON/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.
t2ON/OFF pin is externally re-enabled.
If (t2- t1) ≤ 100 ms, external action of ON/OFF pin
is locked out by start-up inhibit timer.
If (t2- t1) > 100 ms, ON/OFF pin action is internally
enabled.
t3Turn-on inhibit delay period ends. If ON/OFF pin is ON,
converter begins turn-on; if off, converter awaits
ON/OFF pin ON signal; see Figure F.
t4End of converter turn-on delay.
t5Converter VOUT reaches 100% of nominal value.
For the condition, (t2- t1) ≤ 100 ms, the total converter start-up
time (t5- t2) is typically 104 ms. For (t2- t1) > 100 ms, start-up will
be typically 4 ms after release of ON/OFF pin.
ON/OFF
STATE
VOUT
t0t1t2t3
ON
OFF
VIN
t
Fig. F: Start-up scenario #2.
ON/OFF
STATE OFF
ON
VOUT
t0t2t1t5
VIN
t
t4t3
100 ms
Fig. G: Start-up scenario #3.
FEB 10, 2004 revised to NOV 13, 2006 Page 8 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Ambient Tem
p
erature
[
°C
]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
10
20
30
40
50
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
Fig. 1: Available load current vs. ambient air temperature and
airflow rates for QM48S40033 converter mounted vertically
with air flowing from pin 3 to pin 1, MOSFET temperature ≤
120°C, Vin = 48 V.
Load Current [Adc]
0 1020304050
Efficiency
0.65
0.70
0.75
0.80
0.85
0.90
0.95
72 V
48 V
36 V
Fig. 3: Efficiency vs. load current and input voltage for con-
verter 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.
A
mbient Tem
p
erature
[
°C
]
20 30 40 50 60 70 80 90
Load Current [Adc]
0
10
20
30
40
50
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
Fig. 2: Available load current vs. ambient air temperature and
airflow rates for QM48S40033 converter mounted horizontally
with air flowing from pin 3 to pin 1, MOSFET temperature ≤
120°C, Vin = 48 V.
Load Current [Adc]
0 1020304050
Efficiency
0.65
0.70
0.75
0.80
0.85
0.90
0.95
70 C
55 C
40 C
Fig. 4: Efficiency vs. load current and ambient temperature for
converter mounted vertically with Vin = 48 V and air flowing
from pin 3 to pin 1 at a rate of 200 LFM (1.0 m/s).
FEB 10, 2004 revised to NOV 13, 2006 Page 9 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Load Current [Adc]
0 1020304050
P
ower
Di
ss
i
pa
ti
on
[W]
0.00
4.00
8.00
12.00
16.00
72 V
48 V
36 V
Fig. 5: Power dissipation vs. load current and input voltage for
converter mounted vertically with air flowing from pin 3 to pin 1
at a rate of 300 LFM (1.5 m/s) and Ta = 25°C.
Fig. 7: Turn-on transient at full rated load current (resistive)
with no output capacitor at Vin = 48 V, triggered via ON/OFF
pin. Top trace: ON/OFF signal (5 V/div.). Bottom trace: output
voltage (1 V/div.) Time scale: 2 ms/div.
Load Current [Adc]
0 1020304050
ower
ss
pa
on
0.00
4.00
8.00
12.00
16.00
70 C
55 C
40 C
Fig. 6: Power dissipation vs. load current and ambient tem-
perature 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).
Fig. 8: Turn-on transient at full rated load current (resistive)
plus 40,000 µF at Vin = 48 V, triggered via ON/OFF pin. Top
trace: ON/OFF signal (5 V/div.). Bottom trace: output voltage
(1 V/div.). Time scale: 2 ms/div.
FEB 10, 2004 revised to NOV 13, 2006 Page 10 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Fig. 9: Output voltage response to load current step-change
(20 A – 30 A – 20 A) at Vin = 48 V. Top trace: output voltage
(100 mV/div.). Bottom trace: load current (10 A/div). Current
slew rate: 1 A/µs. Co = 470 µF tantalum + 1 µF ceramic. Time
scale: 0.2 ms/div.
Fig. 10: Output voltage ripple (20 mV/div.) at full rated load
current into a resistive load with Co = 10 µF tantalum + 1uF
ceramic and Vin = 48 V. Time scale: 1 µs/div.
Vout
Vsource
i
S
i
C
1 µF
ceramic
capacitor
10 µH
source
inductance
DC/DC
Converter
33 µF
ESR <1
electrolytic
capacitor
Ω
QmaX
Series
QmaXTM
Fig. 11: Test setup for measuring input reflected ripple currents, ic and is.
FEB 10, 2004 revised to NOV 13, 2006 Page 11 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Fig. 12: Input reflected ripple current, is (10 mA/div), meas-
ured through 10 µH at the source at full rated load current
and Vin = 48 V. Refer to Fig. 11 for test setup. Time scale:
1µs/div.
Iout [Adc]
15 60
4.0
Vout [Vdc]
0
0
2.0
1.0
30 45
3.0
Fig. 14: Output voltage vs. load current showing current limit
point and converter shutdown point. Input voltage has al-
most no effect on current limit characteristic.
Fig. 13: Input reflected ripple current, ic (100 mA/div), meas-
ured at input terminals at full rated load current and Vin = 48
V. Refer to Fig. 11 for test setup. Time scale: 1 µs/div.
Fig. 15: Load current (top trace, 20 A/div, 20 ms/div) into a
10 mΩ short circuit during restart, at Vin = 48 V. Bottom
trace (20 A/div, 1 ms/div) is an expansion of the on-time por-
tion of the top trace.
FEB 10, 2004 revised to NOV 13, 2006 Page 12 of 13 www.power-one.com
QM48S40033 DC-DC Converter Data Sheet
3
6
-75 VDC In
p
ut; 3.3 VDC
@
40A Out
p
ut
Physical Information
SIDE VIEW
3
2
1
4
5
6
8
7
TOP VIEW
Pin Connections
Pin # Function
1 Vin (+)
2 ON/OFF
3 Vin (-)
4 Vout (-)
5 SENSE(-)
6 TRIM
7 SENSE(+)
8 Vout (+)
QM48S Platform Notes
• All dimensions are in inches [mm]
• Connector Material: Copper
• Connector Finish: Gold over Nickel
• Converter Weight: 1.06oz [30 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]
Converter Part Numbering Scheme
Product
Series
Input
Voltage
Mounting
Scheme
Rated
Load
Current
Output
Voltage ON/OFF
Logic
Maximum
Height (HT)
Pin
Length (PL)
Special
Features
QM 48 S 40 033 - N S 0 0
Quarter-Brick
Format 36-75 V Surface
Mount
40 A
033 ⇒ 3.3 V N ⇒ Negative
P ⇒ Positive
S ⇒ 0.295”
0 ⇒ 0.00”
0 ⇒ STD
The example above describes P/N QM48S40033-NS00: 36-75 V input, surface mount, 40 A @ 3.3 V output, negative ON/OFF logic and a
maximum height of 0.295”. Please consult factory regarding availability of a specific version.
RoHS Ordering Information:
• No RoHS suffix character is required for lead-solder-exemption compliance.
• For RoHS compliance to all six substances, add the letter "G" as the last letter of the part number.
NUCLEAR AND MEDICAL APPLICATIONS - Power-One products are not designed, intended for use in, or authorized for use as 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.
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.
FEB 10, 2004 revised to NOV 13, 2006 Page 13 of 13 www.power-one.com