The new SSQE48T25012 DC-DC converter is an open frame sixteenth-brick
DC-DC converter that conforms to the Distributed Open Standards
Architecture (DOSA) specifications. The converter operates over an input
voltage range of 36 to 75 VDC, and provides a tightly regulated output voltage
with an output current up to 25 A. The output is fully isolated from the input
and the converter meets Basic Insulation requirements permitting a positive or
negative output configuration.
The converter 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,
overcurrent, and short circuit protections, output voltage trim, and
overtemperature shutdown with hysteresis.
With standard pinout and trim equations and excellent thermal performance,
the SSQE48T25012 converters can replace in most cases existing eighth-brick
converters. Inclusion of this converter in a new design can result in significant
board space and cost savings.
36-75 VDC Input
Industry-standard DOSA pinout
Output: 1.2 V @ 25 A; 30 W
On-board input differential LC-filter
Start-up into pre-biased load
No minimum load required
Weight: 0.44 oz [12.3 g]
Meets Basic Insulation requirements of EN60950
Withstands 100 V input transient for 100 ms
Fixed-frequency operation
Hiccup overcurrent protection
Fully protected (OTP, OCP, OVP, UVLO)
Remote sense
Remote ON/OFF positive or negative logic option
Output voltage trim range: +10%/−20% with industry-standard trim equations
Low height of 0.374” (9.5 mm)
Industry standard 1/16th brick footprint: 0.9” by 1.3”
High reliability: MTBF = 16.23 million hours, calculated per Telcordia TR-332,
Method I Case 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
Approved to the latest edition and amendment of ITE Safety standards, UL/CSA
60950-1 and IEC60950-1
RoHS lead free solder and lead-solder-exempted products are available
2
SSQE48T25012
Conditions: T
A
= 25ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, Cin = 33 µF, unless otherwise specified.
PARAMETER
CONDITIONS /DESCRIPTION
MIN
TYP
MAX
UNITS
Absolute Maximum Ratings
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
0
-40
-55
80
85
125
VDC
°C
°C
Isolation Characteristics
I/O Isolation
Isolation Capacitance
Isolation Resistance
10
2250
150
VDC
pF
MΩ
Feature Characteristics
Switching Frequency
Output Voltage Trim Range
1
Remote Sense Compensation
1
Output Over-voltage Protection
Over-temperature Shutdown (PCB)
Peak Backdrive Output Current during
startup into prebiased output
Backdrive Output Current in OFF state
Auto-Restart Period
Turn-On Time
ON/OFF Control (Positive Logic)
ON/OFF Control (Negative Logic)
Industry-standard equations (1.2 V)
Percent of V
OUT (NOM)
Non-latching
Non-latching
Sinking current from external voltage source
equal V
OUT
(
NOM
) – 0.6V and connected to
output via 1Ohm resistor
Converter OFF
external voltage = 5 VDC
Applies to all protection features
See Figures E, F, and G
Converter Off (logic low)
Converter On (logic high)
Converter Off (logic high)
Converter On (logic low)
-20
2.4
2.4
-20
12.3
Telcordia SR-332, Method I Case 1
50% electrical stress, 40°C ambient
120
130
125
50
10
200
5
0.8
20
20
0.8
411
-20
440
469
+10
+10
140
kHz
%
%
%
°C
mADC
mADC
ms
ms
VDC
VDC
VDC
VDC
g
Mechanical
Weight
Reliability
MTBF
16.23
MHrs
Input Characteristics
Operating Input Voltage Range
Input Under-voltage Lockout
Input Voltage Transient
Maximum Input Current
Input Stand-by Current
Input No Load Current (0 load on the
output)
Input Reflected-Ripple Current, is
Input Voltage Ripple Rejection
Turn-on Threshold
Turn-off Threshold
100ms
V
IN
= 36 VDC , I
OUT
= 25 ADC
Vin = 48V, converter disabled
Vin = 48V, converter enabled
Vin = 48V, 25 MHz bandwidth
120Hz
10
23
10
60
36
33
31
48
34
32
75
35
33
100
1.1
VDC
VDC
VDC
VDC
ADC
mA
mA
mA
PK-PK
dB
1
Vout can be increased up to 10% via the sense leads or 10% via the trim function. However, the total output voltage trim from all
sources shall not exceed 10% of V
OUT
(NOM) in order to ensure specified operation of overvoltage protection circuitry.
tech.support@psbel.com
SSQE48T25012
Output Characteristics
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
Output Voltage Setpoint Accuracy
Output Regulation
Overall Output Voltage Regulation
Output Ripple and Noise – 25 MHz
bandwidth
Plus full resistive load
1.2 VDC
Non-latching, for 1.2 VDC
Non-latching, Short = 10 mΩ
Non-latching
(no load)
Over Line
Over Load
Over line, load and temperature
2
3
30,000
0
27.5
35
8.75
-1.5
±2
±2
-3.0
35
+1.5
±5
±5
+3.0
70
25
35
µF
ADC
ADC
A
Arms
%V
OUT
mV
mV
%Vout
mV
PK-PK
Full load + 10µF tantalum + 1µF ceramic
Co = 1µF ceramic + 10 µF tantalum
Figure 8
Co = 470 µF POS + 1µF ceramic
Figure 9
Dynamic Response
Load Change 50%-75%-50% of Iout Max,
di/dt = 0.1 A/μs
Settling Time to 1% of Vout
Load Change 50%-75%-50% of Iout Max,
di/dt = 5 A/μs
Settling Time to 1% of Vout
30
40
120
40
VOUT = 1.2 VDC
VOUT = 1.2 VDC
83
85.5
mV
µs
mV
µs
%
%
Efficiency
100% Load
50% Load
These power converters have been designed to be stable with no external capacitors when used in low inductance input and
output circuits.
However, in some applications, the inductance associated with the distribution from the power source to the input of the
converter can affect the stability of the converter. A 33 µF electrolytic capacitor with an ESR < 1Ω across the input is
recommended to ensure stability of the converter over the wide range of input source impedance.
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 30,000 µF.
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, both referenced to Vin(-). A typical connection is shown in Fig. A.
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
Vin
ON/OFF
Vin (-)
CONTROL
INPUT
Vout (-)
Figure A. Circuit configuration for ON/OFF function.
2
Operating ambient temperature range is -40ºC to 85ºC
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© 2016 Bel Power Solutions & Protection
4
SSQE48T25012
The positive logic version turns on when the ON/OFF pin is at a logic high and turns off when the pin is at a 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 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.
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 0.2mA at a
low level voltage of
0.8V. An external voltage source (±20V 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 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).
SSQE48 Converter
Vin (+)
(Top View)
ON/OFF
Rw
Vout (+)
100
SENSE (+)
Vin
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
Figure 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.
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.
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 actual output power
remains at or below the maximum allowable output power.
The output voltage can be adjusted up 10% or down 20%. 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, RT-INCR, should be connected between the TRIM (Pin 6) and
SENSE(+) (Pin 7), with a value of:
R
T
INCR
½
where,
5.11
(100
Δ)
V
O
NOM
511
- 10.22
0.6Δ
Δ
, [kΩ],
R
TINCR
½
Required value of trim-up resistor [kΩ]
tech.support@psbel.com
SSQE48T25012
V
O
NOM
½
Nominal value of output voltage [V]
Δ½
V
O
REQ
½
5
(V
O-REQ
V
O-NOM
)
X 100
V
O -NOM
, [%]
Desired (trimmed) output voltage [V].
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.
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
R
T-INCR
Rload
SENSE (+)
Vin
ON/OFF
TRIM
SENSE (-)
Vin (-)
Vout (-)
Figure 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:
R
T
DECR
½
511
10.22
|
Δ
|
, [kΩ]
where,
R
T-DECR
= Required value of trim-down resistor [kΩ] and
Δ
is defined above.
NOTE:
The above equations for calculation of trim resistor values match those typically used in conventional industry-standard
quarterbricks, eighth-bricks and sixteenth-bricks.
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
SENSE (+)
Vin
ON/OFF
TRIM
R
T-DECR
Rload
SENSE (-)
Vin (-)
Vout (-)
Figure 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 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%
This equation is applicable for any condition of output sensing and/or output trim.
[V]
Asia-Pacific
+86 755 298 85888
Europe, Middle East
+353 61 225 977
North America
+1 408 785 5200
BCD.00648_AB
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