UV Detection Question

Added schem

Hello,

When you exceed the UV threshold which in your case is set at 95Vac, your circuit will turn on. And when it is successfully powered up the UV threshold will automatically be reduced by 44% to allow an extended input voltage operating range. So you should expect your circuit to turn back off at around 53Vac/  75VDC.

Hope this answers your question.

Best regards,

PI-Sugomi

Thanks for responding.  The unit does indeed turn off around 53 VAC, but I would like the unit to turn off when it falls below 95VAC instead of the 53 VAC.  Is this possible?  I've been exploring circuits that turn the TOP255 off using the X pin at the 95VAC threshold but wanted to see if there was some way the IC would allow this, or if there was a circuit known in such applications.

scs2016

Hi,

The hysteresis was built into the device to prevent chattering/ unwanted turn on/off if there is any variation in the input voltage. Unfortunately, there is no way that we can disable this hysteresis on the device itself and there are no available circuits that have been tested for such operation. You can explore the remote on/off function of Vpin and Xpin though.

I come up with a circuit that you can try, but this hasn't been tested yet (see attached image). Basically, you need to turn on the transistor after the converter successfully powered up, probably you can use a signal from Vout or bias voltage. When the transistor turns on, this should divert some of the current, effectively increasing the UV threshold/ reducing the hysteresis.