3/3
USER NOTES
Input Voltage
The recommended operating maximum DC input
voltag e is 40V inclusive of the ripple voltage .
Case Grounding
The module case is internally connected to pin 2
and pin 3.
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-R400/2 modules is about 8°C/W. This produces
a 32°C temperature increase of the module surface
for 4W of int ern al power di s sip at ion .
Dep en ding on the am bie nt te mp era tu re 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
stabi lity. T his capacito r canno t hand le larg e values
of high fre quen cy rip ple cu rrent an d it can be p er-
manently damaged if the primary energy source
impedance is not adequate.
The use of an external low ESR, high ripple current
ca pa citor loca ted as cl ose the m odule as possi b le
is recomm en de d.
Suitable capacitors should have a RMS current
capability of 2.5 ARMS with a working voltage of 50
VDC and an ESR o f 0,1Ω at 100kHz. When space
is a lim itation a 22µF ceram ic m ultila ye r capa citor
must be connected to the module input pins.
Output Voltage Programming
The GS-R400V/2 output voltage is programmed by
using a resistor.
The resistor must be located very close the mod ule
and the PCB layou t must min im ize in jected noise.
The va lue of th e re sisto r is ca lcula te d by usi ng the
following formula:
Rv = 2.6 7
Vo
5.1− 1
kΩ
Vo ca n be ad ju sted be twee n 5.1 and 24V.
Module Protection
The modules are protected against occasional and
permanent short circuits of the output pins to
ground. During short circuit (when the output cur-
rent 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
un til the sho rt circuit conditio n is rem oved .
The module can be permanently damaged if the
case temperature exceeds 85° C
Power Derating Curve
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Mi croelectroni cs assumes no respons ibil ity for the
consequences of use of such information nor for any infringement of patents or other r ights of third parties wh ich may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specific ation menti oned
in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.
SGS-THOMSON Mic roel ectro nic s produ cts a re no t a utho rize d f or u se as crit ic al c ompo nent s in l ife support de vi ces o r syst ems wi thou t e xpress
written approval of SGS-THOMSON Microelectronics.
© 1994 SGS-THOMSON Microel ectronics – All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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