SRS4050x012
36-75V Input, 5V 12A Output
Leading the Advancement of Power Conversion
SRS4050x012xxx Sixteenth Brick Converters
Features
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High Efficiency: 91.5% at 5V/17A output
Excellent thermal performance
Low profile in standard footprint: 1.3”x0.9”x0.37’’
Remote sense, remote control, over-voltage, over-
current, short-circuit, and over temperature
protection
Monotonic start-up into pre-biased load
No minimum load required
Fixed frequency operation
Basic Insulation
UL 60950-1 2
nd
edition recognized
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Applications
• Wireless Networks
• Telecom / Datacom
• Electronic Data Processing / Servers
• Distributed Power Architectures
Options
• SMT or through-hole package
• Baseplate
• Auto-restart or lock-up protection mode
• Negative / Positive enable logic
The SRS4 Series of 1/16-Brick DC/DC Converters utilize proprietary technologies to achieve market leading
efficiencies and thermal performance in the latest industry standard package. The 1/16-brick footprint is 43%
smaller than standard 1/8 brick’s, thus saving valuable board real estate. The SRS4 Series of converters
incorporate automated assembly techniques on a single board, low profile design, and are available in both
through-hole and surface mount versions. For higher current operation in extreme thermal environment, a
baseplate is provided as an option. The industry leading performance makes the SRS4 Series of converters
excellent choices for today’s densely packed systems.
The SRS4 converters provide a monotonic start-up from both the input voltage and the ON/OFF control under all
load conditions, including pre-biased output. These converters have a fast dynamic response and are stable over
the full range of input voltage, load current, load capacitance, capacitor ESR, and temperature. They feature tight
line and load regulations, and are fully protected from abnormal conditions of input/output voltages, output current
and operating temperature. The SRS4 converters are an ideal choice for any limited board space, high current
and/or low output voltage applications such as telecom, datacom, wireless networks, or servers.
† UL is a registered trademark of Underwriters Laboratory Inc.
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Datasheet
SRS4050x012xxx
03-22-2012
Page 1
SRS4050x012
36-75V Input, 5V 12A Output
Leading the Advancement of Power Conversion
Absolute Maximum Rating
Excessive stresses over these absolute maximum ratings can cause permanent damage to the converter.
Operation should be limited to the conditions outlined under the Electrical Specification Section.
Parameter
Input Voltage (continuous)
Input Voltage ( < 100ms, operating)
Input Voltage (continuous, non-operating)
I/O Isolation Voltage
Operating Ambient Temperature
(See Thermal Consideration section)
Storage Temperature
Symbol
V
i
V
i
V
i
T
o
T
stg
Min
-0.5
-
-
-
-40
-55
Max
75
100
100
2,250
85*
125
Unit
Vdc
V
dc
V
dc
Vdc
˚C
˚C
* Derating curves provided in this datasheet end at 85ºC ambient temperature. Operation above 85ºC ambient temperature is allowed provided
the temperatures of the key components or the baseplate do not exceed the limit stated in the Thermal Considerations section.
Electrical Specifications
These specifications are valid over the converter’s full range of input voltage, resistive load, and operating
temperature unless noted otherwise.
Input Specifications
Parameter
Input Voltage
Input Current
Quiescent Input Current (Typical Vin)
Standby Input Current
Inrush Transient
Input Reflected-ripple Current, Peak-to-peak
(5 Hz to 20 MHz, 12
μH
source impedance)
Input Ripple Rejection
Input Turn-on Voltage Threshold
Input Turn-off Voltage Threshold
Input Voltage ON/OFF Hysteresis
Symbol
Vi
Iin_
Max
Iin_
Qsnt
Iin_
Stdby
I t
-
-
-
-
2
Min
36
-
-
-
-
Typical
48
-
55
1
-
10
-
35
32
3
Max
75
3.5
75
3
0.1
Unit
V
dc
A
mA
mA
2
As
mA
dB
V
V
V
34
30
36
34
Output Specifications
Parameter
Output Voltage Set Point
Output Voltage Set Point Accuracy
(Vi = Typical Vin; Io = Io_max; Ta = 25°C)
Output Voltage Set Point Accuracy (over all conditions)
Output Regulation:
Line Regulation ( full range input voltage, 1/2 full load)
Load Regulation (full range load, Typical Vin)
Temperature (Ta = -40°C to 85 °C)
Output Current
Output Power
Efficiency
(Typical Vin; Io_max, T
A
= 25ºC)
Output ripple frequency
Output Ripple and Noise Voltage
RMS
Peak-to-peak (5 Hz to 20 MHz bandwidth, Typical Vin)
External Load Capacitance
Symbol
Vo
-
-
-
-
-
I
o
P
o
Min
-1.5
-3
-
-
-
0
0
-
280
-
-
Typical
5.0
Max
+1.5
+3
Unit
V
%Vo
%Vo
%Vo
%Vo
%Vo
A
W
%
kHz
mV
rms
mV
p-p
μF
0.05
0.05
0.1
-
91.5
300
-
-
0.2
0.2
12
60
-
320
45
120
10,000
η
-
-
-
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Datasheet
SRS4050x012xxx
03-22-2012
Page 2
SRS4050x012
36-75V Input, 5V 12A Output
Leading the Advancement of Power Conversion
Output Specifications (continued)
Parameter
Startup Delay, duration from enabling signal to Vo reaches
10% of its set point.
(Typical Vin; Io_max, T
A
= 25ºC )
Startup Time, duration for Vo to rise from 10% of its set
point to within its regulation band.
(Typical Vin; Io_max, T
A
= 25ºC )
Output Over Current Protection Set Point / Io_max
Output Over Voltage Protection Set Point* / Vo_typical
Output Trim Range in % of Vo_typical
Output Remote Sense Range in % of Vo_typical
Dynamic Response
(Vi = 48V; Ta = 25°C; Load transient 0.1A/μs)
Load steps from 50% to 75% of full load:
Peak deviation
Settling time (within 10% band of V
o deviation
)
Load step from 50% to 25% of full load
Peak deviation
Settling time (within10% band of V
o deviation
)
Symbol
Min
Typ
1.5
3
Max
Unit
ms
ms
103
115
80
-
125
-
140
135
110
10
%
%
%
%
3
100
3
100
%Vo
μs
%Vo
μs
General Specifications
Parameter
Remote Enable
Logic Low:
I
ON/OFF
= 1.0mA
V
ON/OFF
= 0.0V
Logic High:
I
ON/OFF
= 0.0μA
Leakage Current
Over-temperature Protection set point
Isolation Capacitance
Isolation Resistance
Calculated MTBF
Telecordia SR-332
,
full load, 40°C, Typ. Vin
Calculated MTBF
Telecordia SR-332
,
50% load, 25°C, Typ. Vin
Symbol
V
ON/OFF
I
ON/OFF
V
ON/OFF
I
ON/OFF
T
o
-
-
Min
0
-
3.5
-
-
-
10
Typ
-
-
-
-
120
1200
-
3.8
6.3
Max
1.2
1.0
15
50
-
-
-
Unit
V
mA
V
μA
°C
pF
MΩ
10 -hou
r
6
10 -hou
r
6
Characteristic Curves
95
90
85
Input Current (A)
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
Vin=36V
1
4
Vin=48V
7
Output Current (A)
NoLoad
HalfLoad
FullLoad
80
Efficiency (%)
75
70
65
60
55
50
10
Vin=75V
0.2
0
30
40
50
Input Voltage
60
70
Figure 1. Efficiency vs. Load Current (25°C)
Figure 2. Input Characteristics
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Datasheet
SRS4050x012xxx
03-22-2012
Page 3
SRS4050x012
36-75V Input, 5V 12A Output
Leading the Advancement of Power Conversion
Output Voltage
(2V/div)
Vin = 36V
Output Voltage Ripple
(100mV/div)
Vin = 48V
Output Control
(5V/div)
Vin = 75V
Time (1ms/div)
Figure 3.
Start-Up from Enable Control
(Typical input voltage and full load
)
Output voltage
(0.5V/div)
Time (2μs/div)
Figure 4.
Output Ripple Voltage at Full Load
Output current
(5A/div)
Output current
(5A/div)
Output voltage
(0.5V/div)
Time – t (100μs/div)
Figure 5.
Transient Load Response
( Typical Vin, 75% to 50% full load step at a slew rate 0.1A/µs)
Time – t (100μs/div)
Figure 6
Transient Load Response
(Typical Vin, 50% to 75% full load step at a slew rate 0.1A/µs)
155℃
140℃
12
10
8
6
N
C
Output Current (A)
110℃
80℃
60℃
4
2
0
0
100LFM
200LFM
300LFM
400LFM
Airflow Direction
1
4
2
Air Flow
25
35
45
55
63
70
85
3
Figure 8.
Thermal Image for Airflow Direction 1
(
11.5A output, 55°C ambient200 LFM, typical Vin,
open frame, unit soldered onto a fixture board.)
Ambient Air Temperature (°C)
Figure 7
. Current Derating Curve for Airflow Direction 1
（Ref.
Figure. 8 for Airflow Direction; typical Vin, open frame, unit
soldered onto a fixture board.)
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Datasheet
SRS4050x012xxx
03-22-2012
Page 4
SRS4050x012
36-75V Input, 5V 12A Output
Leading the Advancement of Power Conversion
Feature Descriptions
ON/OFF
Remote ON/OFF
The converter can be turned on and off by changing the
voltage between the ON/OFF pin and Vin(-). The SRS4
Series of converters are available with factory selectable
positive logic and negative logic.
For the negative control logic, the converter is ON when
the ON/OFF pin is at a logic low level and OFF when the
ON/OFF pin is at a logic high level. For the positive
control logic, the converter is ON when the ON/OFF pin
is at a logic high level and OFF when the ON/OFF pin is
at a logic low level.
With the internal pull-up circuitry, a simple external
switch between the ON/OFF pin and Vin(-) can control
the converter. A few example circuits for controlling the
ON/OFF pin are shown in Figures 9, 10 and 11.
The logic low level is from 0V to 1.2V and the maximum
sink current during logic low is 1mA. The external switch
must be capable of maintaining a logic-low level while
sinking up to this current. The logic high level is from
3.5V to 15V. The converter has an internal pull-up
circuit that ensures the ON/OFF pin at a high logic level
when the leakage current at ON/OFF pin is no greater
than 50μA.
Vin()
Figure 9.
Opto Coupler Enable Circuit
ON/OFF
Vin()
Figure 10.
Open Collector Enable Circuit
TTL/
CMOS
ON/OFF
Vin()
Remote SENSE
The remote SENSE pins are used to sense the voltage
at the load point to accurately regulate the load voltage
and eliminate the impact of the voltage drop in the power
distribution path.
SENSE(+) and SENSE(-) pins should be connected
between the points where voltage regulation is desired.
The voltage between the SENSE pins and the output
pins must not exceed the smaller of 0.5V or 10% of
typical output voltage.
[Vout(+) - Vout(-)] - [SENSE(+) - SENSE (-)] < MIN{0.5V, 10%Vo}
Figure 11.
Direct Logic Drive
Output Voltage Adjustment (Trim)
The trim pin allows the user to adjust the output voltage
set point. To increase the output voltage, an external
resistor is connected between the TRIM pin and
SENSE(+). To decrease the output voltage, an external
resistor is connected between the TRIM pin and
SENSE(-). The output voltage trim range is 80% to
110% of the specified typical output voltage. The circuit
configuration for trim down operation is shown in Figure
14.
To decrease the output voltage, the value of the external
resistor should be
When remote sense is not used, the SENSE pins should
be connected to their corresponding output pins. If the
SENSE pins are left floating, the converter will deliver an
output voltage slightly higher than its specified typical
output voltage.
www.netpowercorp.com
Datasheet
SRS4050x012xxx
03-22-2012
Page 5
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