QM48T50015 DC-DC Converter Data Sheet
36-75 VDC Input; 1.5 VDC @ 50A Output
The
QmaX 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
50A QM48
converters of the
QmaX Series
provide
thermal performance in high temperature environments that
is comparable to or exceeds the industry’s leading 50A 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
QM48T50
converters have a power density more than
twice that of competitors’ 50A half bricks. Over 2 square
inches of board space can be saved for every slot in which a
50A half brick is replaced with a
QM48T50
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
QmaX Series
con-
verters provide standard output voltage for 1.5 V. Output can
be trimmed from –20% to +10% of the nominal output volt-
age, thus providing outstanding design flexibility.
TM
TM
TM
QM48T50015 Converter
Features
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RoHS lead-free solder and lead-solder-exempted
products are available
Delivers up to 50 A @ 1.5 V (75 W)
Industry-standard quarter brick pinout
Higher current capability at 70ºC than most com-
petitors’ 50 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
Lowest profile in industry: 0.31” [7.9 mm]
Lowest weight in industry: 1.1 oz [31.5 g] typical
Meets Basic Insulation requirements of EN60950
Withstands 100 V input transient for 100 ms
Fixed frequency operation
Fully protected
Remote output sense
Output voltage trim range: +10%/−20% with Industry-
standard trim equations
High reliability: MTBF of 2.6 million hours, calculated
per Telcordia TR-332, Method
I
Case 1
Positive or negative logic ON/OFF option
UL 60950 recognized in US and Canada and DEMKO
certified 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
Applications
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Telecommunications
Data communications
Wireless
Servers
MAY 14, 2004 revised to NOV 13, 2006
Page 1 of 13
www.power-one.com
QM48T50015 DC-DC Converter Data Sheet
36-75 VDC Input; 1.5 VDC @ 50A Output
Electrical Specifications
Conditions: T
A
=25ºC, Airflow=300 LFM (1.5 m/s), Vin=48 Vdc, All output voltages, unless otherwise specified.
PARAMETER
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
NOTES
MIN
0
-40
-55
36
TYP
MAX
80
85
125
UNITS
Vdc
°C
°C
Vdc
Vdc
Vdc
Vdc
Vdc
nF
MΩ
kHz
%
%
%
ms
ms
Vdc
Vdc
Vdc
Vdc
INPUT CHARACTERISTICS
Operating Input Voltage Range
Input Under Voltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Voltage Transient
48
34
32
75
35
33
100
Non-latching
33
31
100 ms
2000
1.4
10
415
Industry-std. equations
Percent of V
OUT
(
NOM
)
Non-latching
Applies to all protection features
-20
117
128
100
4
+10
+10
140
ISOLATION CHARACTERISTICS
I/O Isolation
Isolation Capacitance
Isolation Resistance
FEATURE CHARACTERISTICS
Switching Frequency
1
Output Voltage Trim Range
1
Remote Sense Compensation
Output Over-Voltage Protection
Auto-Restart Period
Turn-On Time
ON/OFF Control (Positive Logic)
Converter Off
Converter On
ON/OFF Control (Negative Logic)
Converter Off
Converter On
-20
2.4
2.4
-20
0.8
20
20
0.8
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 V
OUT
(
NOM
), in order to insure specified operation of over-voltage protection circuitry.
MAY 14, 2004 revised to NOV 13, 2006
Page 2 of 13
www.power-one.com
QM48T50015 DC-DC Converter Data Sheet
36-75 VDC Input; 1.5 VDC @ 50A Output
Electrical Specifications (continued)
Conditions: T
A
=25ºC, Airflow=300 LFM (1.5 m/s), Vin=48 Vdc, Vout=1.5 Vdc unless otherwise specified.
PARAMETER
INPUT CHARACTERISTICS
Maximum Input Current
Input Stand-by Current
Input No Load Current (0 load on the output)
Input Reflected-Ripple Current
Input Voltage Ripple Rejection
NOTES
50 Adc, 1.5 Vdc Out @ 36 Vdc In
Vin = 48 V, converter disabled
Vin = 48 V, converter enabled
25MHz bandwidth
120Hz
MIN
TYP
MAX
2.5
UNITS
Adc
mAdc
mAdc
mA
PK-PK
dB
Vdc
mV
mV
Vdc
mV
PK-PK
µF
Adc
Adc
A
Arms
mV
µs
%
%
3
42
7.5
TBD
1.485
1.500
±2
±2
1.515
±4
±4
1.523
50
40,000
50
64
72
18
OUTPUT CHARACTERISTICS
Output Voltage Set Point (no load)
Output Regulation
Over Line
Over Load
Output Voltage Range
Output Ripple and Noise - 25MHz bandwidth
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
Over line, load and temperature
Full load + 10 µF tantalum + 1 µF ceramic
Plus full load (resistive)
Non-latching
Non-latching. Short=10mΩ.
Non-latching
Co = 470 µF tantalum + 1 µF ceramic
2
1.477
30
0
59
DYNAMIC RESPONSE
Load Change 25% of Iout Max, di/dt = 1 A/µS
Setting Time to 1%
150
200
84
88
EFFICIENCY
100% Load
50% Load
Additional Notes: 2. -40ºC to 85ºC
MAY 14, 2004 revised to NOV 13, 2006
Page 3 of 13
www.power-one.com
QM48T50015 DC-DC Converter Data Sheet
36-75 VDC Input; 1.5 VDC @ 50A Output
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.
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).
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
100
Rw
(Top View)
SENSE (+)
TRIM
SENSE (-)
10
Rload
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.
Vin (+)
Vin
ON/OFF
Vin (-)
Vout (-)
Rw
Fig. B:
Remote sense circuit configuration.
QmaX
Series
Converter
(Top View)
TM
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
Vin
ON/OFF
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.
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
Vin (-)
CONTROL
INPUT
Vout (-)
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
MAY 14, 2004 revised to NOV 13, 2006
Page 4 of 13
www.power-one.com
QM48T50015 DC-DC Converter Data Sheet
36-75 VDC Input; 1.5 VDC @ 50A Output
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.
To decrease the output voltage (Fig. D), a trim resistor,
R
T-DECR
, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
R
T
−
DECR
=
511
−
10.22
[k
Ω
]
|
∆
|
Output Voltage Adjust /TRIM (Pin 6)
The output voltage can be adjusted up 10% or down 20% for
Vout
≥
1.5 V, relative to the rated output voltage by the addi-
tion of an externally connected resistor.
The TRIM pin should be left open if trimming is not being
used. To minimize noise pickup, a 0.1
µF
capacitor is con-
nected internally between the TRIM and SENSE(-) pins.
To increase the output voltage, refer to Fig. C. A trim resis-
tor, R
T-INCR
, should be connected between the TRIM (Pin 6)
and SENSE(+) (Pin 7), with a value of:
where,
R
T
−DECR
=
Required value of trim-down resistor [k
Ω
]
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.
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-DECR
Rload
R
T
−
INCR
5.11(100
+
∆)V
O
−
NOM
−
626
=
−
10.22
[k
Ω
]
1.225∆
(Top View)
Vin
ON/OFF
where,
R
T
−INCR
=
Required value of trim-up resistor k
Ω
]
V
O
−NOM
=
Nominal value of output voltage [V]
∆
=
(V
O-REQ
−
V
O -NOM
)
X 100
[%]
V
O -NOM
Vin (-)
Vout (-)
Fig. D:
Configuration for decreasing output voltage.
V
O
−REQ
=
Desired (trimmed) output voltage [V].
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
SENSE (+)
R
T-INCR
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 10%
of V
OUT
(
NOM
)
,
or:
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
(
+
)
−
V
SENSE
(
−
)]
≤
V
O - NOM X
10%
[V]
Rload
(Top View)
Vin
ON/OFF
TRIM
SENSE (-)
Vin (-)
Vout (-)
This equation is applicable for any condition of output sens-
ing and/or output trim.
Fig. C:
Configuration for increasing output voltage.
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.
Protection Features
Input Under-Voltage Lockout
MAY 14, 2004 revised to NOV 13, 2006
Page 5 of 13
www.power-one.com
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