Datasheet GS-R51212 Datasheet (SGS Thomson Microelectronics)

20W TRIPLE OUTPUT STEP-DOWN

FEATURES

MTBF in excess of 200,000 hours
4V max drop-out voltage
Soft start
Reset output
Non-latching short circuit protection
Crow-bar outpu t overvolta ge prote ct ion

DESCRIPTION

The GS-R51212 is a versatile triple output, high
current, high voltage step-down switching regulator
modu le that provi des a +5V and two isolate d 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.

GS-R51212

SWITCHING REGULATOR

MAIN CHARACTERISTICS

V

i

V

o1

I

o1

V

o2

I

o2

V

o3

I

o3

Input Voltage
Output Voltage

Output Current
Output Voltage

Output Current
Output Voltage

Output Current

9 to 40V

5.1V

3.5A
12V

0.1A
12V

0.1A

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

DC Input Voltage

V

i

Reset Output Sink Current

I

rt

T

T

June 1994 1/5

Storage Temperature Range

stg

Operating Case Temperature Range

cop

42 V

20 mA
– 40 to +105 °C
– 20 to +85 °C

GS-R51212

ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise specified)

Symbol Parameter Test Conditions Min Typ Max Unit

Vo1
Vo2
Vo3

∆Vo/∆T

I
Io2
Io3
I
I

V

∆V
∆V

SVR

V

V

I

V

t
t

t
t
t

V

R

Output Voltage Vi = 24V Io1 = 2.5A
Output Voltage Vi=24V Io2 = 0.1A
Output Voltage Vi = 24V Io3 = 0.1A
Temperature Stability All Outputs
Input Voltage

V

i

Output Current Vi = 24V

1

o

Output Current Vi = 24V
Output Current Vi = 24V
Average Input Current Vi = 40V Vo1 = 0V

isc

Average Input Current Vi = 40V Vo1/2/3 = 0V

isc

Reflected Input Current Vi = 24V Io1 = 2.5A Io2,3 = 0.1A

I

ir

5V to 12V Isolation Voltage

is

Switching Frequency

f

s

Efficiency Vi = 24V Io1 = 2.5A Io2,3 = 0.1A

η

Line Regulation Io1 = 2.5A Vi = 15 to 25V Io2,3 = 0.1A

o

Load Regulation Vi = 24V Io1 = 0.5 to 2.5A

o

Supply Voltage Rejection 50/60Hz
Output Ripple Voltage Vi = 24V Io1 = 2.5A

or

Output Noise Voltage Vi = 24V Io1 = 2.5A

on

Reset Leakage Current

rh

Reset Low Level I

rl

Reset Delay Time

rd

Line Transient Recovery Time Io1 = 2.5A Vi = 15 to 35V

r1

Load Transient Recovery T ime Vi = 24V Io = 0.5 to 2.5A

r2

Soft Start Time

ss

Crowbar Delay Time

cd

Crowbar Intervention Threshold

cth

Thermal Resistance Case to ambient

th

Vi = 24V Io2,Io3 = 0.05 to 0.1A

= 5mA

reset

4.95 5.1 5.2 V

11.5 12.5 V

11.5 12.5 V

0.2 mV/°C

940V

0.5 3.5 A

0.1 A

0.1 A

0.1 0.2 A

0.1 0.2 A

200 mApp

200 V

100 kHz

70 %

2 mV/V

35

600

4 mV/V
30 mVpp
40 mVpp

100 µA

0.2 V
100 ms
500 µs
200 µs

10 ms

5 µs

6.37 V
5 °C/W

DC

mV/A

2/5

CONNECTION DIAGRAM AND MECHANICAL DATA

GS-R51212

Di men sions in mm

Bottom view

PIN DESCRIPTION

Pin Function Description

Output 1 Regulated 5.1V output.

1

Output GND Return for output1 current path. Internally connected to pin 8.

2

Output 2 Regulated 12V output.

3

Ground 2 Return of output 3 current path.

4

Output 3 Regulated 12V output.

5

Ground 3 Return of output 3 current path.

6

Reset Open collector Reset output.

7

Input GND Return of input voltage source. Internally connected to pin 2.

8

+ Input DC input voltage. Recommended maximum voltage is 40V.

9

3/5

GS-R51212

USER NOTES
Input Voltage

The reco mmended op erating maxim um DC input
voltage is 40V inclusive of the ripple voltage.

Case Groundin g

The module case is internally con nected to pin 2
and pin 8.
The PCB area below the module can be used as
an effective sixth sid e 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.
Dependi ng on the a mbient te mpe rature an d/or on
the power dissipation, an additional heatsink or
forced ventilation may be required.

Input Impedance

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 loca ted as close to the mo dule as possi­ble is recommended. Suitable capacitors should
have a RMS curre nt capa bility o f 2,5 A
working voltage of 50 V

and an ESR of 0,1Ω at

DC

RMS

with a

100 kHZ. When space is a limitation, a 22µF ce ­ramic multilayer capacitor must be connected to the
module i nput pins.

Figure 1. Outp ut Current Ca pa bili ty vs. Ope rat­ing Conditions

Figure 2. Reset Operation

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 outpu t current at 5V out pu t 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 V

exceeds

o1

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.

4/5

Figure 3. Typical application

GS-R51212

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no respons ibility for the
consequences of use of such information nor for any infringement of patents or other r ights of third parties which may resu lt 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 Microel ectro nics produ cts a re no t a utho rize d f or u se as critical c ompo nent s in l ife support devices or syst ems wi th ou t e xpres s
written approval of SGS-THOMSON Microelectronics.

© 1994 SGS-THOMSON Microelectronics – All Right s Rese rved

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