QM48T/S25050 DC-DC Converter Data Sheet
36-75 VDC Input; 5 VDC @ 25 A Quarter-Brick
The QM Series of high current single output dc-dc
converters sets new standards for thermal performance
and power density in the quarter-brick package.
The QM48T/S25050 converters of the QM Series provide
thermal performance in high temperature environments
that is comparable to or exceeds the industry’s leading 5 V
half-bricks. This is accomplished through the use of patent
pending circuit, packaging and processing techniques to
achieve
ultra-high
efficiency,
excellent
thermal
management, and a very low body profile.
Low body profile and the preclusion of heat sinks minimize
impedance to system airflow, thus enhancing cooling for
both upstream and downstream devices. The use of 100%
automation for assembly, coupled with advanced electric
and thermal design, results in a product with extremely
high reliability.
Operating from a 36-75 V input, the QM Series converters
provide outputs that can be trimmed from –20% to +10%
of the nominal output voltage, thus providing outstanding
design flexibility.
Features
•
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•
•
•
•
•
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•
RoHS lead-free solder and lead-solder-exempted
products are available
Delivers up to 25 A @ 5.0 V
Industry-standard quarter brick pinout
On-board input differential LC-filter
High efficiency – no heat sink required
Start-up into pre-biased output
No minimum load required
Available in through-hole and surface-mount packages
Low profile: 0.28” [7.1 mm] SMT version,
0.31” [7.9 mm] TH version
Low weight: 1.1 oz [31.5 g] typical
Meets Basic Insulation requirements of EN60950
Withstands 100 V input transient for 100 ms
Fixed-frequency operation
Fully protected
Remote output sense
Output voltage trim range: +10%/−20%
with
industry-standard trim equations
High reliability: MTBF of 2.6 million hours,
calculated per Telcordia TR-332, Method
I
Case 1
Positive or negative logic ON/OFF option
UL60950 recognized in US and Canada and
DEMKO certified per IEC/EN60950
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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•
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Telecommunications
Data communications
Wireless
Servers
V4.0 29-March-11
Page 1 of 13
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QM48T/S25050 DC-DC Converter Data Sheet
36-75 VDC Input; 5 VDC @ 25 A Quarter-Brick
Electrical Specifications (QM48T25050 and QM48S25050)
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
PARAMETER
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
NOTES
MIN
0
-40
-55
36
33
31
TYP
MAX
80
85
125
UNITS
VDC
°C
°C
VDC
VDC
VDC
VDC
ADC
mADC
mADC
mA
PK-PK
dB
μF
ADC
ADC
A
Arms
VDC
mV
mV
VDC
mV
PK-PK
VDC
nF
MΩ
kHz
%
%
%
ms
ms
VDC
VDC
VDC
VDC
mV
µs
%
%
INPUT CHARACTERISTICS
Operating Input Voltage Range
Input Under Voltage Lockout Turn-on Threshold
Input Under Voltage Lockout Turn-off Threshold
Input Voltage Transient
Maximum Input Current
Input Stand-by Current
Input No Load Current (0 load on the output)
Input Reflected-Ripple Current
Input Voltage Ripple Rejection
Non-latching
100 ms
25 ADC, 5 VDC Out @ 36 VDC In
Vin = 48 V, converter disabled
Vin = 48 V, converter enabled
25 MHz bandwidth
120 Hz
Plus full load (resistive)
Non-latching
Non-latching. Short = 10
mΩ.
Non-latching
0
26.25
30
31
5.000
±2
±2
30
2000
1.4
10
340
Industry-std. equations
Percent of V
OUT
(
NOM
)
Non-latching
Applies to all protection features
-20
117
128
100
4
+10
+10
140
48
34
32
75
35
33
100
3.9
2.65
52
12.5
TBD
10,000
25
33
50
6.5
5.050
±5
±5
5.075
50
OUTPUT CHARACTERISTICS
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
Output Voltage Set Point (no load)
Output Regulation Over Line
Output Regulation Over Load
Output Voltage Range
Output Ripple and Noise - 25 MHz bandwidth
4.950
Over line, load and temperature
2
Full load + 10 μF tantalum + 1 μF
ceramic
4.925
ISOLATION CHARACTERISTICS
I/O Isolation
Isolation Capacitance
Isolation Resistance
FEATURE CHARACTERISTICS
Switching Frequency
Output Voltage Trim Range
1
Remote Sense Compensation
1
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
Load Change 25% of Iout
Max, di/dt = 1 A/μs
Setting Time to 1%
-20
2.4
2.4
-20
Co = 470 μF tantalum + 1 μF ceramic
120
40
89.5
90.5
0.8
20
20
0.8
DYNAMIC RESPONSE
EFFICIENCY
100% Load
50% Load
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.
2. -40ºC to 85ºC
V4.0 29-March-11
Page 2 of 13
www.power-one.com
QM48T/S25050 DC-DC Converter Data Sheet
36-75 VDC Input; 5 VDC @ 25 A Quarter-Brick
the Start-up Information section for system timing
waveforms associated with use of the ON/OFF pin.
Remote Sense (Pins 5 and 7)
Operation
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.
However, in many applications, the inductance associated
with the distribution from the power source to the input of
the converter can affect the stability of the converter. The
addition of a 33 µF electrolytic capacitor with an ESR <
1
Ω
across the input helps ensure stability of the converter.
In many applications, the user has to use decoupling
capacitance at the load. The power converter will exhibit
stable operation with external load capacitance up to
2,200 µF on 5 V output.
ON/OFF (Pin 2)
The remote sense feature of the converter compensates
for voltage drops occurring between the output pins of the
converter and the load. The SENSE(-) (Pin 5) and
SENSE(+) (Pin 7) pins should be connected at the load or
at the point where regulation is required (see Fig. B).
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
100
Rw
(Top View)
Vin
ON/OFF
SENSE (+)
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
The ON/OFF pin is used to turn the power converter on or
off remotely via a system signal. There are two remote
control options available, positive logic and negative logic
and both are referenced to Vin(-). Typical connections are
shown in Fig. A.
Vin (+)
Fig. B:
Remote sense circuit configuration.
QmaX
Series
Converter
(Top View)
TM
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
If remote sensing is not required, the SENSE(-) pin must
be connected to the Vout(-) pin (Pin 4), and the SENSE(+)
pin must be connected to the Vout(+) pin (Pin 8) to ensure
the converter will regulate at the specified output voltage. If
these connections are not made, the converter will deliver
an output voltage that is slightly higher than the specified
value.
Because the sense leads carry minimal current, large
traces on the end-user board are not required. However,
sense traces should be located close to a ground plane to
minimize system noise and ensure optimum performance.
When wiring discretely, twisted pair wires should be used
to connect the sense lines to the load to reduce
susceptibility to noise.
The converter’s output overvoltage protection (OVP)
senses the voltage across Vout(+) and Vout(-), and not
across the sense lines, so the resistance (and resulting
voltage drop) between the output pins of the converter and
the load should be minimized to prevent unwanted
triggering of the OVP.
When utilizing the remote sense feature, care must be
taken not to exceed the maximum allowable output power
capability of the converter, equal to the product of the
nominal output voltage and the allowable output current for
the given conditions.
When using remote sense, the output voltage at the
converter can be increased by as much as 10% above the
nominal rating in order to maintain the required voltage
across the load. Therefore, the designer must, if
necessary, decrease the maximum current (originally
Vin
ON/OFF
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 logic high and turns off when at logic low. The
converter is on when the ON/OFF pin is left open
.
The negative logic version turns on when the pin is at logic
low and turns off when the pin is at logic high. The
ON/OFF pin can be hard wired directly to Vin(-) to enable
automatic power up of the converter without the need of an
external control signal.
ON/OFF pin is internally pulled-up to 5 V through a
resistor. A mechanical switch, open collector transistor, or
FET can be used to drive the input of the ON/OFF pin. The
device must be capable of sinking up to 0.2 mA at a low
level voltage of
≤
0.8 V. An external voltage source of
±20
V max. may be connected directly to the ON/OFF
input, in which case it should be capable of sourcing or
sinking up to 1 mA depending on the signal polarity. See
MAR 27, 2003 revised to SEP 28, 2006
Page 3 of 13
www.power-one.com
QM48T/S25050 DC-DC Converter Data Sheet
36-75 VDC Input; 5 VDC @ 25 A Quarter-Brick
obtained from the derating curves) by the same
percentage to ensure the converter’s actual output power
remains at or below the maximum allowable output power.
Output Voltage Adjust /TRIM (Pin 6)
R
T
−
DECR
=
where,
511
−
10.22
[kΩ]
|
Δ
|
The output voltage can be adjusted up 10% or down 20%
relative to the rated output voltage by the addition of an
externally connected resistor.
The TRIM pin should be left open if trimming is not being
used. To minimize noise pickup, a 0.1 µF capacitor is
connected internally between the TRIM and SENSE(-)
pins.
To increase the output voltage, refer to Fig. C. A trim
resistor, R
T-INCR
, should be connected between the TRIM
(Pin 6) and SENSE(+) (Pin 7), with a value of:
R
T
−DECR
=
Required value of trim-down resistor [kΩ]
and
Δ
is as defined above.
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industry-
standard quarter-bricks. More information can be found in
Output Voltage Trim Feature Application Note.
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
SENSE (+)
TRIM
R
T-DECR
Rload
(Top View)
Vin
ON/OFF
SENSE (-)
Vin (-)
Vout (-)
R
T
−
INCR
=
where,
5.11(100
+
Δ)V
O
−
NOM
−
626
−
10.22
[kΩ]
1.225Δ
Fig. D:
Configuration for decreasing output voltage.
R
T
−INCR
=
Required value of trim-up resistor kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
Δ
=
(V
O -REQ
−
V
O -NOM
)
X 100
[%]
V
O -NOM
Trimming/sensing beyond 110% of the rated output
voltage is not an acceptable design practice, as this
condition could cause unwanted triggering of the output
overvoltage protection (OVP) circuit. The designer should
ensure that the difference between the voltages across the
converter’s output pins and its sense pins does not exceed
0.50 V, or:
V
O
−REQ
=
Desired (trimmed) output voltage [V].
When trimming up, care must be taken not to exceed the
converter‘s maximum allowable output power. See
previous section for a complete discussion of this
requirement.
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
(
+
)
−
V
SENSE
(
−
)]
≤
0.50
[V]
This equation is applicable for any condition of output
sensing and/or output trim.
Vin (+)
QmaX
Series
Converter
TM
Vout (+)
SENSE (+)
R
T-INCR
(Top View)
Vin
ON/OFF
TRIM
SENSE (-)
Rload
Vin (-)
Vout (-)
Fig. C:
Configuration for increasing output voltage.
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:
MAR 27, 2003 revised to SEP 28, 2006
Page 4 of 13
www.power-one.com
QM48T/S25050 DC-DC Converter Data Sheet
36-75 VDC Input; 5 VDC @ 25 A Quarter-Brick
To comply with safety agencies’ requirements, an input
line fuse must be used external to the converter. A fuse
with rating of 7A is recommended for use with this product.
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 their
converters to several system level standards, primary of
which is the more stringent EN55022,
Information
technology equipment - Radio disturbance characteristics -
Limits and methods of measurement.
Effective internal LC differential filter significantly reduces
input reflected ripple current, and improves EMC.
With the addition of a simple external filter, all versions of
the QM Series of converters pass the requirements of
Class B conducted emissions per EN55022 and FCC, and
meet at a minimum, Class A radiated emissions per EN
55022 and Class B per FCC Title 47CFR, Part 15-J.
Please contact Power-One Applications Engineering for
details of this testing.
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 at least 35 V for the converter to
turn on. Once the converter has been turned on, it will shut
off when the input voltage drops below 31 V. This feature
is beneficial in preventing deep discharging of batteries
used in telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or short-
circuit conditions. Upon sensing an overcurrent condition,
the converter will switch to constant current operation and
thereby begin to reduce output voltage. When the output
voltage drops below 60% of the nominal value of output
voltage, the converter will shut down.
Once the converter has shut down, it will attempt to restart
nominally every 100 ms with a typical 3% duty cycle. The
attempted restart will continue indefinitely until the
overload or short circuit conditions are removed or the
output voltage rises above 60% of its nominal value.
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
reference, independent of the output voltage regulation
loop. Once the converter has shut down, it will attempt to
restart every 100 ms until the OVP condition is removed.
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
Fig. H:
Location of the thermocouple for thermal testing.
The converters meet North American and International
safety regulatory requirements per UL60950 and
EN60950. Basic Insulation is provided between input and
output.
MAR 27, 2003 revised to SEP 28, 2006
Page 5 of 13
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