SSQ48T20025 DC-DC Converter Data Sheet
36-75 VDC Input, 2.5 VDC @ 20 A Output
Features
RoHS lead free
for all six substances
Delivers 18.9 A output current at 70 °C, 200 LFM
Industry-standard DOSA footprint
Weight: 0.422 oz (11.95 g)
0.40” (10.16 mm) height profile
On-board input differential LC-filter
Start-up into pre-biased load
No minimum load required
Meets Basic Insulation requirements of EN60950
Withstands 100 V input transient for 100 ms
Operating ambient temperature: -40 °C to 85 °C
Fixed-frequency operation
Hiccup overcurrent protection
Fully protected (OTP, OCP, OVP, UVLO)
Remote Sense
Remote ON/OFF (Positive or negative logic)
Output voltage trim range: +10%/−20% with
industry-standard trim equations
•
UL60950 recognized in US and Canada and
DEMKO certified per IEC/EN60950 (pending)
•
Designed to meet Class B conducted emissions per
FCC and EN55022 when used with external filter
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All materials meet UL94, V-0 flammability rating
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Applications
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Intermediate Bus Architectures
Telecommunications
Data communications
Wireless communications
Servers, workstations
Benefits
•
High efficiency – no heat sink required
•
Cost-effective, single board design
•
Small size and low-profile
Description
The SSQ48T20025 power module is an open frame sixteenth-brick dc-dc converter that conforms to the
Distributed Open Standards Architecture (DOSA) specifications. The module operates over an input voltage range
of 36 to 75 VDC, and provides a regulated output voltage of 2.5 VDC with an output current up to 20 A for today’s
Distributed Power Architecture. The output is fully isolated from the input; the module meets Basic Insulation
requirements and permits a positive or negative output configuration.
The module is constructed using a single-board approach with both planar and discrete magnetics. The standard
feature set includes remote On/Off (positive or negative logic), input undervoltage lockout, output
overvoltage shutdown, output overcurrent shutdown, output voltage trim, and overtemperature shutdown with
hysteresis.
The SSQ48 Series of converters is available in both surface-mount (SSQ48S-) and through-hole (SSQ48T-)
versions.
MAY 16, 2006 revised to JUN 16, 2006
Page 1 of 13
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SSQ48T20025 DC-DC Converter Data Sheet
36-75 VDC Input, 2.5 VDC @ 20 A Output
Electrical Specifications
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
Input Characteristics
Operating Input Voltage Range
Input Undervoltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Voltage Transient
Isolation Characteristics
I/O Isolation
Feature Characteristics
Switching Frequency
Output Voltage Trim Range
1
Remote Sense Compensation
1
Notes
Continuous
Min
0
-40
-55
36
Typ
Max
100
85
125
Units
VDC
°C
°C
VDC
VDC
VDC
VDC
VDC
48
33.7
31.2
75
35
33
100
Non-latching
33
29
100 ms
1500
375
Industry-std. equations
Percent of V
OUT
(
NOM
)
Latching (Auto Recovery optional)
2
Non-latching
Applies to all protection features
See Fig. F and Fig. G
-20
2.4
2.4
-20
-20
120
127
125
200
30
0.8
20
20
0.8
+10
+10
134
kHz
%
%
%
°C
ms
ms
VDC
VDC
VDC
VDC
Output Overvoltage Protection
Overtemperature Shutdown (PCB)
Auto-Restart Period
Turn-On Time
ON/OFF Control (Positive Logic)
Converter Off (logic low)
Converter On (logic high)
ON/OFF Control (Negative Logic)
Converter Off (logic high)
Converter On (logic low)
Additional Notes:
1
Vout can be increased up to 10% via the sense leads or up to 10% via the trim function. However, the total output voltage trim from all
sources should not exceed 10% of V
OUT
(
NOM
), in order to ensure specified operation of overvoltage protection circuitry.
2
Please consult factory for details.
MAY 16, 2006 revised to JUN 16, 2006
Page 2 of 13
www.power-one.com
SSQ48T20025 DC-DC Converter Data Sheet
36-75 VDC Input, 2.5 VDC @ 20 A Output
Electrical Specifications (continued)
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 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
Output Characteristics
Output Voltage Set Point (no load)
Output Regulation
Over Line
Over Load
Output Voltage Range
Output Ripple and Noise – 25 MHz
bandwidth
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
Dynamic Response
Load Change 10A-20A-10A, di/dt = 0.1 A/μs
di/dt = 1 A/μs
Settling Time to 1%
Efficiency
100% Load
50% Load
Additional Notes:
3
Notes
20 ADC, 2.5 VDC Out @ 36 VDC In
Vin = 48 VDC, converter disabled
Vin = 48 VDC, converter enabled
20 MHz bandwidth
120 Hz
Min
Typ
Max
2
Units
ADC
mADC
mADC
mA
PK-PK
dB
4
60
10
-
2.44
2.479
±2
±2
2.517
±5
±5
2.535
50
10,000
0
20
26
28
3
300
500
150
88.6
87.5
30
22
VDC
mV
mV
VDC
mV
PK-PK
μF
ADC
ADC
A
Arms
mV
mV
µs
%
%
Over line, load and temperature
3
Full load + 10
μF
tantalum + 1
μF
ceramic
Plus full load (resistive)
Non-latching
Non-latching. Short = 10 mΩ.
Non-latching. Short = 10 mΩ.
Co = 1
μF
ceramic
Co = 270
μF
OSCON + 1
μF
ceramic
2.433
2.479
20
-40 ºC to 85 ºC
.
MAY 16, 2006 revised to JUN 16, 2006
Page 3 of 13
www.power-one.com
SSQ48T20025 DC-DC Converter Data Sheet
36-75 VDC Input, 2.5 VDC @ 20 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 33 µF electrolytic capacitor with an
ESR < 1
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 10,000 µF on 2.5 V
output.
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.
SSQ48 Converter
(Top View)
Vin
ON/OFF
to the ON/OFF input, in which case it must be
capable of sinking up to 2 mA.
Remote Sense (Pins 5 and 7)
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).
SSQ48 Converter
(Top View)
ON/OFF
Vout (+)
100
Rw
Vin (+)
SENSE (+)
Vin
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
Fig. B: Remote sense circuit configuration.
CAUTION
If remote sensing is not utilized, 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 data
sheet value.
Vin (+)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
Because the sense leads carry minimal current,
large traces on the end-user board are not required.
However, sense traces should be run side by side
and located close to a ground plane to minimize
system noise and ensure optimum performance.
When using the remote sense function, 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, which is
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 obtained from the derating curves)
by the same percentage to ensure the converter’s
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 converter is on when the ON/OFF pin is left
open. See the Electrical Specification section for
logic high/low definitions.
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 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 de-bounced
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 0.5 mA
at a low level voltage of
≤
0.8 V. An external voltage
source (±20 V maximum) may be connected directly
MAY 16, 2006 revised to JUN 16, 2006
Page 4 of 13
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SSQ48T20025 DC-DC Converter Data Sheet
36-75 VDC Input, 2.5 VDC @ 20 A Output
actual output power remains at or below the
maximum 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 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:
⎡
5.11
×
V
O
−
NOM
×
(100
+
Δ)
511
⎤
−
−
10.22
⎥
[kΩ]
R
T
−
INCR
= ⎢
1.225Δ
Δ
⎣
⎦
Note:
The above equations for calculation of trim resistor values
match those typically used in conventional industry-standard
quarter-bricks, eighth-bricks and sixteenth-bricks.
Vin (+)
SSQ48 Converter
(Top View)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
R
T-DECR
Vin
ON/OFF
Vin (-)
Vout (-)
Fig. D: Configuration for decreasing output voltage.
where,
R
T
−INCR
=
Required value of trim-up resistor [kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
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 10% of V
OUT
(
NOM
),
or:
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
+
)
−
V
SENSE
−
)]
≤
V
O - NOM X
10%
[V]
(
(
(V
O-REQ
−
V
O-NOM
)
Δ
=
V
O -NOM
X
100
[%]
This equation is applicable for any condition of
output sensing and/or output trim.
V
O
−REQ
=
Desired (trimmed) output voltage [V].
SSQ48 Converter
(Top View)
SENSE (+)
Vin
ON/OFF
TRIM
SENSE (-)
Vin (-)
Vout (-)
R
T-INCR
Rload
Protection Features
Vout (+)
Vin (+)
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 33.7 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 29 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. Typically, when the output voltage drops
below 40% of the nominal output voltage, the
converter will shut down.
Once the converter has shut down, it will attempt to
restart nominally every 200 ms with a typical 3-5%
duty cycle. The attempted restart will continue
indefinitely until the overload or short circuit
conditions are removed.
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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 the previous section for a complete discussion
of this requirement.
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:
⎡
511
⎤
R
T
−
DECR
= ⎢
−
10.22
⎥
⎣
Δ
⎦
[kΩ]
where,
R
T
−DECR
=
Required value of trim-down resistor [kΩ]
and
Δ
is defined above.
MAY 16, 2006 revised to JUN 16, 2006
Page 5 of 13
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