Hi to everybody,
I'm using the circuit suggest by the Motorola application note DRM039 (circuit of page 23); everything works fine but during the product certification I found that the 2KV surge disturb destroys the circuit!!
Transil diodes D11 and D18 aren't able to protect the IGBTs. Also a varistor S10K300 at the AC line input is not sufficient to stop the surge transient. I tried to use strong IGBTs (IXYH8N250CHV) without positive results. The load is a 45W fan motor.
Anybody use that circuit? Suggestions to solve my problem?
Thanks a lot.
