3/3

USER NOTES

Input Voltage

The recommended operating maximum DC input

voltage 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 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

Ω at 100kHz. When space

is a limitation a 22

µF ceramic multilayer capacitor

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 module

and the PCB layout must minimize injected noise.

The value of the resistor is calculated by using the

following formula:

= 2.67







5.1

− 1







k

Ω

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

until the short circuit condition is removed.

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 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

SGS-THOMSON Microelectronics GROUP OF COMPANIES

Australia - Brazil - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands -

Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A.

GS-R400/2 FAMILY