cupoftea
Advanced Member level 5
Hi,
We are using the Power Integrations Innoswtich for a 20W, 90-264VAC, 0.8A offline flyback.
The previous FSGM0565 controller has gone obselete. However, we got loads of transformers built and so are stuck with the present 84/19 = NP/NS transformer.
We are NOT using a synchronous FET...we are disabling that.
The Power Integrations Innoswtich has a FWD pin. The FWD pin gets connected to the secondary side switching node. This detects when the secondary coil has "discharged"...and it then starts to turn on the primary FET.
Problem is, our transformer NP/NS is too low, and the leakage spike will overvoltage the FWD pin. Therefore we need to clamp the FWD pin.
Will the attached (ringed) circuit be ok for this....?.....it should not give any significant delay to the dv/dt at the FWD pin, for obvious reasons.
Basically, the INNOswitch also has a pin ("VOUT") which directly senses the vout....so the innoswitch simply detects whenever the FWD pin flys up above vout.....at this moment, the innoswitch knows that it can turn on the primary FET, because the secondary coil must have "discharged".
Innoswitch CE (we use the INNO3165C)
LTspice and jpeg as attached.
We are using the Power Integrations Innoswtich for a 20W, 90-264VAC, 0.8A offline flyback.
The previous FSGM0565 controller has gone obselete. However, we got loads of transformers built and so are stuck with the present 84/19 = NP/NS transformer.
We are NOT using a synchronous FET...we are disabling that.
The Power Integrations Innoswtich has a FWD pin. The FWD pin gets connected to the secondary side switching node. This detects when the secondary coil has "discharged"...and it then starts to turn on the primary FET.
Problem is, our transformer NP/NS is too low, and the leakage spike will overvoltage the FWD pin. Therefore we need to clamp the FWD pin.
Will the attached (ringed) circuit be ok for this....?.....it should not give any significant delay to the dv/dt at the FWD pin, for obvious reasons.
Basically, the INNOswitch also has a pin ("VOUT") which directly senses the vout....so the innoswitch simply detects whenever the FWD pin flys up above vout.....at this moment, the innoswitch knows that it can turn on the primary FET, because the secondary coil must have "discharged".
Innoswitch CE (we use the INNO3165C)
LTspice and jpeg as attached.
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