SSQE48T25018 DC-DC Converter
36-75 VDC Input; 1.8 VDC, 25 A Output
Data Sheet
Features
•
RoHS lead-free solder and lead-solder-exempted
products are available
•
Industry-standard DOSA pinout
•
Output: 1.8 V at 25 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” (9.5mm)
•
Industry standard 1/16
th
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
Applications
•
•
•
•
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 new SSQE48T25018 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 SSQE48T25018 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.
ZD-02091 Rev. 1.0
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Page 1 of 12
SSQE48T25018 DC-DC Converter
36-75 VDC Input; 1.8 VDC, 25 A Output
Data Sheet
Electrical Specifications
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, Cin=33 µF, unless otherwise specified.
Parameter
Absolute Maximum Ratings
Input Voltage
Operating Ambient Temperature
Storage Temperature
Notes
Continuous
Min
0
-40
-55
2250
Typ
Max
80
85
125
Units
VDC
°C
°C
VDC
Isolation Characteristics
I/O Isolation
Isolation Capacitance
Isolation Resistance
10
440
Industry-standard equations (1.8V)
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
-20
2.4
2.4
-20
12.3
Telcordia SR-332, Method I Case 1
50% electrical stress, 40°C ambient
16.23
120
130
125
50
10
200
5
0.8
20
20
0.8
-20
+10
+10
140
150
pF
MΩ
kHz
%
%
%
°C
mADC
mADC
ms
ms
VDC
VDC
VDC
VDC
g
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
MHrs
Additional Notes:
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.
ZD-02091 Rev. 1.0
www.power-one.com
Page 2 of 12
SSQE48T25018 DC-DC Converter
36-75 VDC Input; 1.8 VDC, 25 A Output
Data Sheet
Electrical Specifications (continued)
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, Cin=33 µF, unless otherwise specified.
Parameter
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)
Input Reflected-Ripple Current,
Input Voltage Ripple Rejection
Notes
Min
36
33
31
Typ
48
34
32
Max
75
35
33
100
1.5
Units
VDC
VDC
VDC
VDC
ADC
mA
mA
mA
PK-PK
dB
100 ms
V
IN
= 36VDC , I
OUT
=25ADC
Vin = 48V, converter disabled
Vin = 48V, converter enabled
Vin = 48V, 25 MHz bandwidth
120 Hz
Plus full resistive load
1.8 VDC
Non-latching, for 1.8 VDC
Non-latching, Short = 10 mΩ
Non-latching
-1.5
±2
±2
Over line, load and temperature
Full load + 10 µF tantalum + 1 µF
ceramic
Co = 1 µF ceramic + 10 uF tantalum
Figure 8
Co = 470 µF POS + 1 µF ceramic
Figure 9
2
10
31
10
60
30,000
0
27.5
35
8.75
+1.5
±5
±5
+3.0
50
80
25
35
i
s
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
-3.0
mV
mV
%Vout
mV
PK-PK
µF
ADC
ADC
A
Arms
%V
OUT
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
150
40
V
OUT
= 1.8 VDC
V
OUT
= 1.8 VDC
85.3
87.5
mV
µs
mV
µs
%
%
Efficiency
100% Load
50% Load
Additional Notes:
2
Operating ambient temperature range is -40 ºC to 85 ºC
ZD-02091 Rev. 1.0
www.power-one.com
Page 3 of 12
SSQE48T25018 DC-DC Converter
36-75 VDC Input; 1.8 VDC, 25 A Output
Data Sheet
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.
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 < 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 30,000 µF.
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, both referenced to Vin(-). A typical
connection is shown in Fig. A.
SSQE48 Converter
(Top View)
Vin
ON/OFF
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.
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).
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
100
Rw
SENSE (+)
Vin
ON/OFF
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
Vin (-)
CONTROL
INPUT
Vout (-)
Fig. A: Circuit configuration for ON/OFF function.
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
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
ZD-02091 Rev. 1.0
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Page 4 of 12
SSQE48T25018 DC-DC Converter
36-75 VDC Input; 1.8 VDC, 25 A Output
Data Sheet
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.
Output Voltage Adjust /TRIM (Pin 6)
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:
511
−
10.22
, [kΩ]
|
∆
|
R
T
−
DECR
=
where,
R
T-DECR
= Required value of trim-down resistor [kΩ]
and
∆
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.
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-DECR
Rload
R
T
−
INCR
5.11(100
+
∆)V
O
−
NOM
−
626
=
−
10.22
, [kΩ],
1.225∆
Vin
ON/OFF
Vin (-)
Vout (-)
where,
R
T
−INCR
=
Required value of trim-up resistor [kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
Fig. D: Configuration for decreasing output voltage.
∆
=
(V
O -REQ
−
V
O-NOM
)
X 100
, [%]
V
O -NOM
V
O
−REQ
=
Desired (trimmed) 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:
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.
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
+
)
−
V
SENSE
−
)]
≤
V
O - NOM X
10%
[V]
(
(
This equation is applicable for any condition of
output sensing and/or output trim.
Vin (+)
SSQE48 Converter
(Top View)
Vout (+)
R
T-INCR
Rload
SENSE (+)
Vin
ON/OFF
TRIM
SENSE (-)
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:
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