GS-R400 Family
20W TO 140W STEP-DOWN
SWITCHING REGULATOR FAMILY
FEATURES
MTBF in excess of 200,000 hours
4A max output current
46V max input voltage
4V max drop-out voltage
Soft start
Remote logic inhibit/enable
Remote output voltage sense
Non-latching overload and short circuit protection
Crow-bar output overvoltage protection
DESCRIPTION
The GS-R400 series is a versatile family of high
current, high voltage step-down switching voltage
regulators.
The integral heatsink allows a large power handling
capability and it provides also an effective shielding
to minimize EMI.
SELECTION CHART
Type
Ordering
Number
GS-R405
GS-R412
GS-R415
GS-R424
GS-R405S
GS-R400V
GS-R400VB
Output
Voltage
(V)
5.1
±
2%
12.0
±
4%
15.0
±
4%
24.0
±
4%
5.1
±
2%
5.1 to 40
5.1 to 40
Input
Voltage
(V)
9 to 46
16 to 46
19 to 46
28 to 46
9 to 46
Vo+4 to 46
Vo+4 to 46
Output
Ripple
(mVpp)
25
50
65
100
25
25 to 100
25 to 100
Regulation
Line
(mV/V)
2
5
5
6
2
6
6
Load
(mV/A)
20
40
60
90
20
20 to 90
20 to 90
Efficiency
Notes
(%)
70
80
85
90
70
70 to 90
70 to 90
Reset output
Progr. output voltage
Progr. output voltage and
current. Frequency synchr.
Fixed output voltage
"
"
"
Note:
The line regulation is measured at I
out
=1A
The load regulation is measured at V
in
=V
o
+8V and I
out
=1 to 3A
For V
O
≥
36V and I
o
= 4A an external heatsink or forced ventilation are required.
ABSOLUTE MAXIMUM RATINGS
Symbol
Vi
Irt*
Tstg
Tcop
DC Input Voltage
Reset Output Sink Current
Storage Temperature Range
Operating Case Temperature Range
Parameter
Value
48
20
– 40 to +105
– 20 to +85
Unit
V
mA
°C
°C
* GS-R405S only
June 1994
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GS-R400 FAMILY
CONNECTION DIAGRAM AND MECHANICAL DATA
Pin 2
GS-R405S only
Pin 5,6,7 GS-R400VB only
Pin 12
GS-R400V/VB only
Dimensions in mm
Bottom view
PIN DESCRIPTION
Pin
1
2
3
4
5
6
7
8
9
10
11
12
Function
Inhibit
Reset
+ Input
Input GND
Oscillator
Sync
Current limiting
Output GND
– Sense
+ Sense
+ Output
Program
Description
The module is disabled by a high logic level applied to this pin.
Reset output (GS-R405S only).
DC input voltage. Recommended maximum voltage is 46V.
Return for input voltage source.
100kHz oscillator output. To be connected to Sync (pin 6) input if the unit is a master and
left open if it is a slave (GS-R400VB only). See fig. 5.
Synchronization input. To be connected to the Oscillator output (pin 5) of the master (GS-
R400VB only). See fig. 5.
A resistor (≥ 2.2kΩ) connected from this pin to pin 9 sets the current limiting level
(GS-R400VB only).
Return for output current path.
Internally connected to pin 4.
Senses the remote load return. Must be tied to pin 8 when the remote sensing feature is
not used. See fig. 1.
Senses the remote load high side. Must be tied to pin 11 when the remote load sensing
feature is not used. See fig. 1.
Regulated DC output voltage.
A resistor (≤ 18kΩ) connected between this pin and pin 10 sets the output voltage
(GS-R400V and GS-R400VB only).
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GS-R400 FAMILY
ELECTRICAL CHARACTERISTICS
(T
A
= 25°C unless otherwise specified)
Symbol
∆V
o/∆T
Io
IoL
Iisc
fs
SVR
Vr
tss
Vinhl
Vinhh
Iinhh
tcb
Vrh*
Vrl*
trd*
Vcth
∆V
o
Rth
Parameter
Temperature Stability
Output Current
Current Limit
Average Input Current
Switching Frequency
Supply Voltage Rejection
Ripple Voltage
Soft Start Time
Low Inhibit Voltage
High Inhibit Voltage
High Inhibit Input Current
Crow-bar Delay Time
Reset High Level
Reset Low Level
Reset Delay Time
Crowbar Intervention Threshold
Total Remote
Sense Compensation
Thermal Resistance
Case to ambient
5
Irl = 5mA
Irl = 10mA
100
Vo
•1.25
500
Vinh = 5V
5
5
0.2
0.4
2
Test Conditions
Vi = Vo+8V Io = 1A
Vi = Vo+8V
Vi = Vo+8V
Vi = 46V Output Shorted
Io = 1A
fo = 100Hz Io =1A
Io = 2A
Vi = Vo+8V
0.2
5
0.1
100
4/12
25/150
10/35
0.8
5.5
500
Min
Typ
0.2/1.6
4
8
0.2
Max
Unit
mv/°C
A
A
A
KHz
mV/V
mVpp
ms
V
V
µA
µs
V
V
ms
V
mV
°C/W
* GS-R405S only
USER NOTES
Input Voltage
The recommended operating maximum DC input
voltage is 46V inclusive of the ripple voltage.
Remote Sensing
The remote voltage sense compensation range is
for a total drop of 500mV equally shared between
the load connecting wires. It is a good practice to
shield the sensing wires to avoid oscillation.
Each sense input must be connected to its compan-
ion output power pin when the remote sense capa-
bility is not used (see fig. 1).
Case Grounding
The module case is isolated from the electrical
circuit of the switching regulator. It can be grounded
using the 4 corner pins.
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 all the
GS-R400 modules is about 5°C/W. This produces
a 50°C temperature increase of the module surface
for 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
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 per-
manently damaged if the primary energy source
impedance is not adequate. The use of an external
low ESR, high ripple current capacitor located as
close the module as possible is recommended.
Suitable capacitors should have a RMS current
capability of 2.5A
RMS
with a working voltage of 50
V
DC
and an ESR of 0,1Ω at 100 kHz. When space
3/5
GS-R400 FAMILY
is a limitation, a 22µF ceramic multilayer capacitor
must be connected to the module input pins.
Output Voltage Programming
The GS-R400V and GS-R400VB output voltage is
programmed by using a resistor (see pin function
table and fig. 4). The resistor must be located very
close the module and the PCB layout must
mimimize injected noise. The value of the resistor
is calculated by using the following formula:
V
o
–1
kΩ
R
v
=
2.67
5.1
V
o
can be adjusted between 5.1 and 40V.
Current Limiting Programming
The GS-R400VB current limiting is programmed by
using a resistor (see pin function table and fig. 4).
Figure 1. Load Connection
The value of the resistor is calculated by using the
following formula:
R
i
= [2.2 + (5•I
o
)] kΩ
Module Protection
The modules are protected against occasional and
permanent short circuits of the output pin to ground,
as well as against output current overload.
When the output current 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 crowbar output overvoltage protection is activated
whenever the output voltage exceeds the nominal
output voltage by more than 25%.
Figure 2. Remote Inhibit Operation
Figure 3. Reset Operation
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GS-R400 FAMILY
Figure 4. Voltage and Current Programming
Figure 5. Multiple Units Synchronization
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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