STMICROELECTRONICS GS

GS-R51212
20W TRIPLE OUTPUT STEP-DOWN
SWITCHING REGULATOR
FEATURES
MTBF in excess of 200,000 hours
4V max drop-out voltage
Soft start
Reset output
Non-latching short circuit protection
Crow-bar output overvoltage protection
DESCRIPTION
The GS-R51212 is a versatile triple output, high
current, high voltage step-down switching regulator
module that provides a +5V and two isolated 12V
outputs. It is ideal for microprocessor based boards
because it powers the logic and the communication
ports and it has a Reset output for the correct
system start-up.
The integral heatsink allows a large power handling
capability and it provides also an effective shielding
to minimize EMI.
MAIN CHARACTERISTICS
Vi
Input Voltage
9 to 40V
Vo1
Io1
Output Voltage
Output Current
5.1V
3.5A
Vo2
Io2
Output Voltage
Output Current
12V
0.1A
Vo3
Io3
Output Voltage
Output Current
12V
0.1A
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
Vi
DC Input Voltage
42
V
Irt
Reset Output Sink Current
20
mA
Tstg
Storage Temperature Range
– 40 to +105
°C
Tcop
Operating Case Temperature Range
– 20 to +85
°C
June 1994
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GS-R51212
ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise specified)
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
5.1
5.2
V
Vo1
Output Voltage
Vi = 24V
Io1 = 2.5A
4.95
Vo2
Output Voltage
Vi=24V
Io2 = 0.1A
11.5
12.5
V
Vo3
Output Voltage
Vi = 24V
Io3 = 0.1A
11.5
12.5
V
Temperature Stability
All Outputs
∆Vo/∆T
Vi
Input Voltage
Io1
Output Current
Vi = 24V
Io2
Output Current
Io3
0.2
mV/°C
9
40
V
0.5
3.5
A
Vi = 24V
0.1
A
Output Current
Vi = 24V
0.1
A
Iisc
Average Input Current
Vi = 40V
Vo1 = 0V
0.1
0.2
A
Iisc
Average Input Current
Vi = 40V
Vo1/2/3 = 0V
0.1
0.2
A
Iir
Reflected Input Current
Vi = 24V
Io1 = 2.5A Io2,3 = 0.1A
200
Vis
5V to 12V Isolation Voltage
200
fs
Switching Frequency
η
Efficiency
Vi = 24V
∆Vo
mApp
VDC
100
kHz
Io1 = 2.5A Io2,3 = 0.1A
70
%
Line Regulation
Io1 = 2.5A Vi = 15 to 25V Io2,3 = 0.1A
2
mV/V
∆Vo
Load Regulation
Vi = 24V
Vi = 24V
35
600
mV/A
SVR
Supply Voltage Rejection
50/60Hz
4
mV/V
Vor
Output Ripple Voltage
Vi = 24V
Io1 = 2.5A
30
mVpp
Von
Output Noise Voltage
Vi = 24V
Io1 = 2.5A
40
mVpp
100
µA
0.2
V
100
ms
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Io1 = 0.5 to 2.5A
Io2,Io3 = 0.05 to 0.1A
Irh
Reset Leakage Current
Vrl
Reset Low Level
trd
Reset Delay Time
tr1
Line Transient Recovery Time
Io1 = 2.5A
Vi = 15 to 35V
500
µs
tr2
Load Transient Recovery Time
Vi = 24V
Io = 0.5 to 2.5A
200
µs
tss
Soft Start Time
10
ms
tcd
Crowbar Delay Time
5
µs
6.37
V
5
°C/W
Vcth
Crowbar Intervention Threshold
Rth
Thermal Resistance
Ireset = 5mA
Case to ambient
GS-R51212
CONNECTION DIAGRAM AND MECHANICAL DATA
Bottom view
Dimensions in mm
PIN DESCRIPTION
Pin
Function
Description
1
Output 1
Regulated 5.1V output.
2
Output GND
Return for output1 current path. Internally connected to pin 8.
3
Output 2
Regulated 12V output.
4
Ground 2
Return of output 3 current path.
5
Output 3
Regulated 12V output.
6
Ground 3
Return of output 3 current path.
7
Reset
Open collector Reset output.
8
Input GND
Return of input voltage source. Internally connected to pin 2.
9
+ Input
DC input voltage. Recommended maximum voltage is 40V.
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GS-R51212
USER NOTES
Input Voltage
Figure 1. Output Current Capability vs. Operating Conditions
The recommended operating maximum DC input
voltage is 40V inclusive of the ripple voltage.
Case Grounding
The module case is internally connected to pin 2
and pin 8.
The PCB area below the module can be used as
an effective sixth side shield against EMI.
Thermal Characteristics
The case-to-ambient thermal resistance of the
GS-R51212 module is about 5°C/W. This produces
a 50°C temperature increase of the module surface
for a 10W of internal power dissipation.
Depending on the ambient temperature and/or on
the power dissipation, an additional heatsink or
forced ventilation may be required.
Input Impedance
Figure 2. Reset Operation
The module has an internal capacitor connected
between the input pins in order to assure PWM
stability. This capacitor cannot handle large values
of high frequency ripple current, and it can be
permanently damaged if the primary energy source
impedance is not adequate.
The use of an external low ESR, high ripple current
capacitor located as close to the module as possible is recommended. Suitable capacitors should
have a RMS current capability of 2,5 ARMS with a
working voltage of 50 VDC and an ESR of 0,1Ω at
100 kHZ. When space is a limitation, a 22µF ceramic multilayer capacitor must be connected to the
module input pins.
Module Protection
The module is protected against occasional and
permanent short circuits of the output pins to
ground, as well as against output current overload.
When the output current at 5V output exceeds the
maximum value, the output is automatically disabled. After a fixed time the module starts again in
a soft mode. The cycle is repeated until the overload
condition is removed.
A crow-bar output overvoltage protection is activated when the output voltage on Vo1 exceeds
6.37V.
Output Current
The output current of the main output is 3.5A. The
max output current of the two 12V outputs is a
function of the input voltage and of the main output
current as shown in fig. 1.
If the main current is zero, no voltage will be available on the 12V outputs.
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Figure 3. Typical application
GS-R51212
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification mentioned
in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.
SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express
written approval of SGS-THOMSON Microelectronics.
© 1994 SGS-THOMSON Microelectronics – All Rights Reserved
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