Datasheet GS-R1012 Datasheet (SGS Thomson Microelectronics)

GS-R1012

120W STEP-DOWN SWITCHING REGULATOR

Type V

GS-R1012 18 to 36 V 12 V 10 A

i

V

o

I

o

FEATURES

Wide inputvoltage range (18 to 36V)
High efficiency(90%min.)
Paralleloperation with current sharing
Synchronization
Remote inhibit/enable
Remote load voltage sense
Output short-circuitprotection
Soft-start
PCB or chassismountable

DESCRIPTION

The GS-R1012 is a step-down switching voltage
regulator suitable to provide 12V/10A output volt­age from a wide input voltage range (18 to 36V).

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

DC Input Voltage
High Inhibit voltage
Storage Temperature Range
Operating Case Temperature Range

40 V
28 V

– 20 to +105 °C

0 to +75 °C

V

T

T

V
iinh

stg

cop

i

June 1994 1/7

GS-R1012

ELECTRICALCHARACTERISTICS (T

Symbol

Input Voltage Vo= 12V Io= 1.5 to 10A

V

i

Input Current Vi= 24V Io= 10A

l

i

Reflected Input Current Vi= 24V Io= 10A

l

ir

V

V

l

iinh

V

V

δV

δV

∆V

I

I

osc

δI

t

tr1

tr2

R

* Note: when output current isless than1.5A, output ripple voltage increases due to discontinuous operation.

Enable Input Voltage Vi= 18 to 36V Io= 1.5 to 10A

ien

Inhibit Input Voltage Vi= 18 to 36V Io= 1.5 to 10A

iinh

Inhibit Input Current Vi= 18 to 36V Io=1.5 to 10A

Output Voltage Vi= 18 to 36V Io= 1.5 to 10A

o

Output Ripple

or

Voltage
Line Regulation Vi= 18 to 36V Io= 10A

OL

Load Regulation Vi= 24V Io= 1.5 to 10A

OO

Remote Sense

o

Compensation
Output Current* Vi= 18 to 36V Vo= 12V

I

o

Output Current

ol

Limiting
Short-circuit Output

Current
Current Sharing

o

Deviation

Soft-start Time Vi= 24V Io= 10A

ss

Line Transient
Recovery Time

Load Transient
Recovery Time

Switching Frequency Vi= 24V Io= 1.5 to 10A

f

s

η Efficiency Vi

Thermal Resistance

thc

Case-to-ambient

Parameter Test Conditions Min Typ Max Unit

=25°C unless otherwise specified)

amb

with external filter (C = 1000µF)

V

=5V

iinh

Vi= 24V
Io= 10A

Vi= 24V
Io= 10A

Vi= 18 to 36V

Vi= 24V

Vi= 24V
Io= 2 to 10A two modules in
parallel

Vi= 15 to 36V
Io=5A

Vi= 24V Io= 1.5 to 10A

= 18 to 36V Io= 10A

18 24 36 V

0 1.2 V
224V

11.4 12 12.6 V

010A

10.5 11.5 A

90 92 %

5,6 A

400 500 mApp

0.3 0.5 mA

150 mVpp

0.5 %
1%

0.5 V

16 A

10 %

15 ms
60 µs

100 µs

100 kHz

7.5 °C/W

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CONNECTION DIAGRAM AND MECHANICAL DATA

GS-R1012

Dimensionsin mm (inches).

PIN DESCRIPTION

Pin Function Description

1 GND Input
2 Inhibit

3 + Vin

4,5 + Vout

6 + Sense

7 Sync
8 Parallel
9 -Sense

10,11 GND Output

Return for input voltage source. Internally connected topin 10,11.
The converter is ON (Enable) when this pin is unconnected or the voltageapplied is lower

than 1.2V.The converter is OFF (Inhibit) for a control voltage in the range of 2 to24V.
DC Input voltage; recommended maximum voltage is 36V.

External capacitor between pin 3and pin 1 is mandatory; recommended value is
1000µF/50V for switching application.

+12V output voltage.
Senses the remote load high side. To be connectedto pin4,5 when remote sense is not

used.
Synchronization output. See figures 1,2,3,4. Take care to leave the pin open when is not

used.
Parallel output. See figures 1,2,3,4. Takecare to leave the pin open when is not used.
Senses the remote load return. To be connected to pin 10,11 when remote sense is not

used.In parallel configuration, take care to connect all -S pins together (see figures 1,2,3,4).
Return for output current path. Internally connected to pin 1.

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GS-R1012

USER NOTES
Input Voltage

The recommended operating maximum DC input
voltage is 36V inclusive of the ripplevoltage. The
use of an external low ESR, high ripple current
capacitor located as close the module as possible
is mandatory;recommendedvalue is 1000µF/50V.

Softstart

To avoid heavy inrush current the output voltage
rise time is typically15ms in anyconditionof load.

Remote Sensing

The remote voltage sense compensationrange is
for a totaldrop of 500mV equally shared between
the load connectingwires. It is a good practice to
shield the sensing wires to avoidoscillations. See
the connection diagramon figures 1, 2, 3, 4.

Figure1. Figure 2.

ParallelOperation

To increase available output regulated power, the
module features the parallelconnectionpossibility
with equal currentsharingand maximum deviation
of 10% (two modulesin parallel). See the connec­tion diagram on figures 1, 2, 3, 4.

Module Protection

The module is protected against occasional and
permanent shortcircuits of the output pins to
ground,as well as against output current overload.
It usesa currentlimitingprotectioncircuitry, avoid­ing latch-up problems with certain types of loads.

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Figure 3. Figure 4.

GS-R1012

Thermal characteristics: how to choose the
heat-sink

Sometimes the GS-R1012 requires an external
heat-sink depending both operating temperature
conditionsand power.

Beforeentering into calculationsdetails, some ba­sic concepts will be explainedto better understand
the problem.

The thermal resistance between two points is rep­resentedby theirtemperature differencein front of
a specifieddissipatedpower, and it is expressedin
Degree Centigrade per Watt (°C/W).

For GS-R1012 thethermal resistancecase to am­bientis7.5°C/W. This means that an internalpower
dissipationof 1Wwill bring thecasetemperatureat

7.5°C abovethe ambient temperature.
The maximumcasetemperaturetowhich themod-

ule provides 10Ais 75°C (see fig. 6).
Let’ssuppose to have a GS-R1012that delivers a

load current of 10Aat an ambient temperature of
40°C.

Thedissipated powerin thisoperating condition is
about10.4W (at typicalefficiencyof 92%), and the
casetemperatureof the modulewill be:

T

= T

Case

Amb

+ Pd× R

=40 + 10.4 × 7.5 = 118°C

th

Thisvalueexceedsthemaximumallowedtempera­ture and an external heat-sink must be added. To
this purpose four holes (see mechanical drawing)
areprovided on themetal surface of the module.

To calculatethisheat-sink,let’sfirstdeterminewhat
the totalthermal resistanceshould be.

T

CaseMAX

=

R

th

− T

P

d

amb

75

− 40

=

= 3.37°C/W

10.4

This value is the resulting value of the additional
heatsinkthermal resistance.

5/7

GS-R1012

Figure5. - Efficiency vs. Output Current.

Typ. eff. (%)

98
97
96
95
94
93
92
91
90
89
88

012345678910

Vi= 18V

Vi= 24V

Vi= 36V

Figure6. - Output Currentvs. T case.

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GS-R1012

The following list may help the designer to select
the propercommerciallyavailableheat-sink.
Sometimes it can be more convenient to use a

Manufacturers Type Height (mm) Rth (°C/W)

ALUTRONIC PR139 20 3

PR140 19 2
PR159 20 2.5

ASSMAN V5440 19 3

V5805 15 2
V5280 19 2

AAVID 60885 14 4.5

60660 25.5 1.5
62355 33.5 3

AUSTERLITZ KS50 12 3

KS100.3 15 2.5

FISCHER SK16 25.5 1.5

SK52 19 2

SGE BOSARI L30 21 3

LZ50 24 3

THERMALLOY 6155 14 4.5

6601 14 5
6176 24 4.5
6320 30 1.5

custom made heat-sink that can be experimently
designed and tested.

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the
consequences of use of such informationnor for any infringement of patents or other rights of third parties which may result from its use. No
license is granted by implicationor 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 productsare notauthorized for use ascritical components inlife supportdevices or systems without express
written approval of SGS-THOMSON Microelectronics.

 1994 SGS-THOMSON Microelectronics – All Rights Reserved

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