The new SSQE48T20033 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 20 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 SSQE48T20033 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.
RoHS lead-free solder and lead-solder-exempted
products are available
Industry-standard DOSA pinout
Output: 3.3 V at 20 A
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
UL60950 recognized in US and Canada and DEMKO
certified per IEC/EN60950
Designed to meet Class B conducted emissions per
FCC and EN55022 when used with external filter
All materials meet UL94, V-0 flammability rating
Telecommunications
Data communications
Wireless communications
Servers, Workstations
High efficiency – no heat sink required
Cost effective, single board design
Small size and low-profile
.
North America
+1-866.513.2839
Asia-Pacific
+86.755.29885888
Europe, Middle East
+353 61 225 977
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© 2015 Bel Power Solutions, inc.
BCD.00647_AA
Conditions: T
A
= 26 º C, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, Cin = 33 µ F, unless otherwise specified.
PARAMETER
Absolute Maximum Ratings
Input Voltage
Operating Ambient Temperature
Storage Temperature
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
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)
Converter Off (logic low)
Converter On (logic high)
ON/OFF Control (Negative Logic)
Converter Off (logic high)
Converter On (logic low)
Mechanical
Weight
Reliability
MTBF
Input Characteristics
Operating Input Voltage Range
Input Under-voltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Voltage Transient
Maximum Input Current
Input Stand-by Current
Input No Load Current (0 load on the output)
100 mS
V
IN
= 36VDC , I
OUT
=20ADC
Vin = 48V, converter disabled
Vin = 48V, converter enabled
10
43
33
31
34
32
35
33
100
2.1
VDC
VDC
VDC
ADC
mA
mA
36
48
75
VDC
Telcordia SR-332, Method I Case 1
50% electrical stress, 40° C ambient
16.23
MHrs
12.3
g
2.4
-20
20
0.8
VDC
VDC
-20
2.4
0.8
20
VDC
VDC
Industry-standard equations (3.3V)
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 1Ω resistor
Converter is OFF;
External voltage=5 VDC
Applies to all protection features
See Figures E, F, and G
1.5
120
130
125
50
10
200
5
10
-20
440
+10
+10
140
kHz
%
%
%
°C
mADC
mADC
mS
mS
10
2250
150
VDC
pF
MΩ
Continuous
0
-40
-55
80
85
125
VDC
°C
°C
DESCRIPTION / CONDITION
MIN
TYP
MAX
UNITS
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BCD.00647_AA
Input Reflected-Ripple Current, i
s
Input Voltage Ripple Rejection
Output Characteristics
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
Output Voltage Setpoint Accuracy (no load)
Output Regulation
Over Line
Over Load
Overall Output Voltage Regulation
Output Ripple and Noise – 25 MHz bandwidth
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
Efficiency
100% Load
50% Load
Vin = 48V, 25 MHz bandwidth
120 Hz
10
60
20
mA
PK-PK
dB
Plus full resistive load
3.3 VDC
Non-latching, for 3.3 VDC
Non-latching, Short = 10 mΩ
Non-latching
-1.5
0
21
25
28
6
20,000
20
28
µF
ADC
ADC
A
Arms
+1.5
%V
OUT
±2
±2
Over line, load and temperature
2
Full load + 10 µ F tantalum + 1 µ F ceramic
-2.5
70
±5
±5
+2.5
mV
mV
%Vout
mV
PK-PK
Co = 1 µ F ceramic + 10 uF tantalum
Figure 8
30
40
mV
µs
mV
µs
Figure 8
Co = 470 µ F POS + 1 µ F ceramic
Figure 9
100
40
V
OUT
= 3.3 VDC
V
OUT
= 3.3 VDC
91
91
%
%
Additional Notes:
1
Vout
2
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.
Derating ambient temperature range is -40 ºC to 85 ºC
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 µ F electrolytic capacitor with an ESR < 1
Ω
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 20,000 µ F.
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.
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BCD.00647_AA
F
ig. A: Circuit configuration for ON/OFF function
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
Vin
ON/OFF
Vin (-)
CONTROL
INPUT
Vout (-)
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 0.2 mA at
a low level voltage 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 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).
Fig. B: Remote sense circuit configuration
SSQE48 Converter
Vin (+)
(Top View)
ON/OFF
Rw
Vout (+)
100
SENSE (+)
Vin
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
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.
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BCD.00647_AA
The output voltage can be adjusted up 10% or down 20%. Trim up to 10% is guaranteed only at Vin≥40V, and it is
approximately 8% to 10% at Vin = 36V.
The TRIM pin should be left open if trimming is not being used. To minimize noise pickup, a 0.1 µ F 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
INCR
½
where,
5.11(100
Δ)V
O
NOM
626
10.22
1.225Δ
[kΩ],
R
TINCR
½
Required value of trim-up resistor [kΩ]
V
ONOM
½
Nominal value of output voltage [V]
Δ
½
(V
O-REQ
V
O-NOM
)
X 100
V
O -NOM
[%]
V
OREQ
½
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.
Fig. C: Configuration for increasing output voltage.
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
R
T-INCR
Rload
SENSE (+)
Vin
ON/OFF
TRIM
SENSE (-)
Vin (-)
Vout (-)
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 quarter-bricks, eighth-bricks
and sixteenth-bricks.
Fig. D: Configuration for decreasing output voltage
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
SENSE (+)
Vin
ON/OFF
TRIM
R
T-DECR
Rload
SENSE (-)
Vin (-)
Vout (-)
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]
1
This equation is applicable for any condition of output sensing and/or output trim.
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BCD.00647_AA
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