GS-R1005
50W STEP-DOWN SWITCHINGREGULATOR
Type V
GS-R1005 12 to 36 V 5 V 10 A
i
V
o
I
o
FEATURES
Wide inputvoltage range (12 to 36V)
High efficiency(80% min.)
Paralleloperation with current sharing
Synchronization
Remote inhibit/enable
Remote load voltagesense
Output short-circuitprotection
Soft-start
PCB or chassismountable
DESCRIPTION
The GS-R1005 is a step-down switching voltage
regulatorsuitable toprovide5V/10Aoutput voltage
froma wideinput voltagerange (12 to 36V).
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
DC Input Voltage
High Inhibitvoltage
Operating Case Temperature Range
Storage TemperatureRange
40 V
28 V
0 to +75 °C
– 20 to +105 °C
V
T
T
V
iinh
cop
stg
i
June 1994 1/7
GS-R1005
ELECTRICALCHARACTERISTICS (T
Symbol
Input Voltage Vo= 5.05V Io= 1.2 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 than 1.2A, output ripplevoltage increases due to discontinuous operation.
Enable Input Voltage Vi= 12 to 36V Io= 1.2 to 10A
ien
InhibitInput Voltage Vi= 12 to 36V Io= 1.2 to 10A
iinh
InhibitInput Current Vi= 12 to 36V Io=1.2 to 10A
Output Voltage Vi= 12 to 36V Io= 1.2 to 10A
o
Output Ripple
or
Voltage
Line Regulation Vi= 12 to 36V Io= 10A
OL
Load Regulation Vi= 24V Io= 1.2 to 10A
OO
Total Remote Sense
o
Compensation
Output Current* Vi= 12 to 36V Vo= 5.05V
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= 1.2 to 10A
f
s
Efficiency Vi= 12 to 36V Io= 10A
η
Thermal Resistance
thc
Case-to-ambient
Parameter Test Conditions Min Typ Max Unit
=25°C unless otherwise specified)
amb
with external filter (C = 470µF)
V
=5V
iinh
Vi= 24V
Io= 10A
Vi= 24V
Io= 10A
Vi= 12 to 36V
Vi= 24V
Vi= 24V
Io= 2to 10A two modules in
parallel
Vi= 12 to 36V
Io=5A
Vi= 24V Io= 1.2 to 10A
12 24 36 V
0 1.2 V
224V
4.9 5.05 5.2 V
010A
12.5 13.7 A
80 83 %
2.5 A
200 220 mApp
0.3 0.5 mA
100 120 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-R1005
Package R.Dimensions in 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 inputvoltage source. Internally connectedto pin 10,11.
The converter is ON (Enable) when this pin is unconnected or the voltage applied is lower
than 1.2V.The converteris OFF (Inhibit) for a control voltage in the range of 2 to 24V.
DC Input voltage; recommended maximum voltage is 36V.
External capacitor between pin 3 and pin 1 is mandatory; recommended value is
470µF/50V for switching application.
+5V output voltage.
Sensesthe remote loadhigh side. To be connected to pin 4,5 when remote sense is not
used.
Synchronization output. See figures 1,2,3,4. Open when not used.
Parallel output. See figures 1,2,3,4. Open when not used.
Sensesthe remote loadreturn. To be connected to pin 10,11when 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-R1005
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 locatedas close the moduleas possible
is mandatory; recommendedvalueis 470µF/50V.
Softstart
To avoid heavy inrush current the output voltage
rise time is typically 15msin any condition of load.
Remote Sensing
ParallelOperation
To increase available output regulated power, the
module featuresthe parallelconnection possibility
with equal currentsharingand maximumdeviation
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 againstoutputcurrentoverload.
It uses a current limiting protectioncircuitry, avoiding latch-up problems with certain types of loads.
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 connectiondiagramon figures 1, 2, 3,4.
Figure1. Figure 2.
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Figure 3. Figure 4.
GS-R1005
Thermal characteristics: how to choose the
heat-sink
Sometimes the GS-R1005 requires an external
heat-sinkdependingonboth operatingtemperature
conditionsandpower.
Before entering intocalculationsdetails, some basic concepts will be explainedto better understand
the problem.
The thermalresistance between two pointsis representedby theirtemperaturedifference in front of
a specifieddissipated power, and it is expressedin
Degree Centigrade per Watt (°C/W).
For GS-R1005 the thermal resistance case to ambientis7.5°C/W. Thismeansthataninternalpower
dissipationof 1Wwill bringthecasetemperatureat
7.5°C abovethe ambienttemperature.
Themaximumcasetemperature,atwhichthemod-
ule provides10A, is 75°C (seefig. 6).
Let’ssuppose to have a GS-R1005that delivers a
load current of 10Aat an ambient temperature of
40°C.
The dissipated power in thisoperating condition is
about10.2W (at typicalefficiency of 83%), and the
case temperature of the module willbe:
T
= T
Case
Amb
+ Pd× R
= 40 + 10.2 × 7.5 = 116.8 °C
th
Thisvalueexceedsthe maximumallowedtemperature and an external heat-sink must be added. To
this purpose four holes (seemechanical drawing)
are provided on themetal surfaceof the module.
To calculatethisheat-sink,let’sfirstdeterminewhat
the totalthermal resistanceshould be.
T
CaseMAX
=
R
th
− T
P
d
amb
75
− 40
=
= 3.42°C/W
10.2
This value is the resulting value of the additional
heatsinkthermal resistance.
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GS-R1005
Figure5. - Efficiency vs. Output Current.
Typ. eff. (%)
90
89
88
87
Vi= 12V
86
85
84
83
82
81
80
012345678910
Figure6. - Output Currentvs. T case.
Vi= 24V
Vi= 36V
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GS-R1005
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 information nor for any infringement of patents orother rightsof third parties which may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSONMicroelectronics. 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 notauthorized for use ascritical components inlife support devices or systems withoutexpress
written approval of SGS-THOMSONMicroelectronics.
1994 SGS-THOMSON Microelectronics –All Rights Reserved
Australia - Brazil - China - France - Germany- Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - TheNetherlands -
Singapore - Spain - Sweden - Switzerland - Taiwan- Thailand - United Kingdom - U.S.A.
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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