How to reduce VIPER17 start-up voltage (from the default ≈100 Vdc to 50 Vdc)

Status
Not open for further replies.
E

emontllo

Full Member level 4
Joined
May 9, 2011
Messages
194
Helped
62
Reputation
124
Reaction score
59
Trophy points
1,308
Visit site
Activity points
2,694
Hello,

I would like to operate a flyback converter at a wide rectified voltage range (from 50 Vdc to 380 Vdc). My design is currently based on the ST VIPER17L.

Is there any way to reduce the start-up voltage of a VIPER? Although the Brown out protection can be deactivated and the flyback can effectively work at 50 Vdc rectified voltage, it is not possible to start the driver at low voltage.

I have already tested the flyback with a start-up voltage of 100 Vdc and then reduced the bus voltage to 50 Vdc it and it does work perfectly.

Any recommendation, external power-up circuit, or suggestion would be greatly appreciated.
 

Re: How to reduce VIPER17 start-up voltage (from the default ≈100 Vdc to 50 Vdc)

I just designed this small circuit (reusing some components already in the flyback circuit). This charges the Vdd capacitor with 2 mA until it reaches 10 V.
If the auxiliary winding is providing power to Vdd it should reach 14 V --> precharge circuit off. I chosed a PNP transistor that should withstand the peak power during initial charge.

Any comments?

 

Re: How to reduce VIPER17 start-up voltage (from the default ≈100 Vdc to 50 Vdc)

I have already tested this precharge circuit to power the IC externally and it still does not work. Definitively, the VIPER requires a drain voltage between 80V and 100V to start operation. I will need to switch to a different flyback control / drive IC.

 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…