shift in output current after potting and zener in V pin
Posted by: Osnirok
on
Using potting compound in LNK PH series, poliurethane ou poliester resin, I see an increasing in output current. for example 2A to 2,3amps. This phenomena in yur opinion is more related with V pin resistors ou Fedback pin resistor ?
and, in some designs there is a zener diode in V pin. What is the porpose of this zener? Aplication note tell about a resistors in this place...
Thanks.
The output current variation with potting material is related with the sensitivity of Vpin, not FB pin.
There is 15 V ESD clamp to limit the voltage with 4 Meg resistor in series with the Vpin, and a zener diode in Vpin could be used to limit the Vpin voltage lower than 15 V during start up until BP capacitor is charged.