SR036SG Ver la hoja de datos (PDF) - Supertex Inc

Número de pieza

componentes Descripción

Fabricante

SR036SG

Inductorless, Dual Output Off-Line Regulators

Supertex Inc 

SR03x

Technical Bulletin

SR03x Power On Surge Protection

When power is first applied to an SR03x circuit

near the peak of the input sine wave, there is an

instantaneous step of voltage at the HVIN terminal.

The same step is applied to the pass element

(MOSFET or IGBT). The parasitic capacitances in

the pass element (MOSFET or IGBT) form a

voltage divider circuit that applies an attenuated

step to the gate of the pass element in the direction

to turn on the pass element.

If the input step voltage is large enough, the pass

element will be turned on. The high impedance

gate drive of the SR03x is not strong enough to

shut down the pass element in time. The pass

element will conduct high current while there is a

large voltage across it. This over heats the pass

element and destroys it. In turn, the SR03x is also

destroyed.

It has been reported that this power-on circuit

destruction occurs frequently on 230VAC inputs

and occasionally on 120VAC inputs.

The protection circuit, shown below, controls the

gate drive and clamps the current through the pass

element to approximately 3 Amperes (exact current

not critical). This allows the SR03x enough time to

shut down the pass element.

As shown in the circuit diagram, the surge

protection requires only a resistor and a low cost

NPN transistor (MPSA06 or equivalent).

Power On Surge Protection Circuit Diagram

A110204

Share Link: