Problem with L6566BH wide range input (90-400Vac)

ufficiotecnico · ‎2013-08-22

Posted on August 22, 2013 at 15:08

Hi

We used eDesignSuit. The Vin is designed from 90Vac to 400Vac (phase-neutral or phase-phase)

and the Vout is 16V, 1.3A (max) (about 21W), in QR mode with fmin 150kHz and Fmax 300kHz.

If we supply the circuit with 400Vac, after a few hours of work, the Rs burns as well as the resistor in series to the gate of the mosfet

and the mosfet goes in short. In some cases the L6566BH explodes. In past we used the L6565 and the same thing happened.

If we supply the circuit with 230Vac, all works well without problems.

Attached the schematic designed.

What can it be?

Someone can help us?

Thank you for

#l6566bh

Sirichai JAIPACHR · ‎2014-02-03

Posted on February 04, 2014 at 05:18

Your selective (900V) mosfet is seem too low of voltage rated.

Vds = Vin(max) + ( Vout x Turn Ratio) + some extra spike (around 10% of V_reflect)

Vds = (400Vac x 1.414) + (16 x Turn Ratio) + ( 16 x Turn Ratio x 0.1)

therefore mosfet burnt when it's operated at high input voltage.

Hope it help