UC2843AQ: UC2843AQ startup optimization

5t34m

Part Number: UC2843AQ

Dear team,

please support on following:

tested UC2843AQ and preparing the schematics with "startup Circuite".
We have following question:

How to implement a faster start up time but keep power dissipation LOW on Rstart? Especially at high voltage (110V)
We have the idea to use voltage stabilisation(insteat Rstart) with one NPN transistor which wil be active only at start up.

Maybe you have some additional ideas?

Thanks

over 5 years ago

0 Benjamin Lough over 5 years ago

TI__Mastermind 26695 points

Hi 5t34m,

You could use a high value resistor string + zener to bias a high voltage mosfet to provide a faster startup time but keep the static power loss low. Take a look at PMP7760 as an example implementation. Zener D100 biases the gate of Q100 on for initital charge up of VIN. After startup, the bias winding takes over and Q100 turns off. The only static power loss would be in the resistor string + zener

http://www.ti.com/tool/PMP7760?keyMatch=high%20voltage%20start&tisearch=Search-EN-Everything

Best Regards,

Ben Lough

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UC2843AQ: UC2843AQ startup optimization