UC1825: Regarding usage of UC1825 for 1MHZ switching frequency CCM Flyback converter

TI_Electronics

Intellectual 345 points

Part Number: UC1825

Is it possible to use UC1825 in 5V, 5A output (CCM) flyback converter operating at switching frequency of 1MHz?

over 7 years ago

0 Ramesh Khanna over 7 years ago

TI__Expert 7445 points

Hi Kamlesh,

As highlighted in the datasheet oscillator can operate up to 1Mhz. As the two output pulses Out A and Out B will be offset as in Push-pull configuration. How are you planning to drive the flyback Mosfet?

Can you sketch a schematic as to what you have in mind.

If you use one of the output i.e. Out A to drive the flyback Mosfet then flyback will be operating at half the oscillator frequency.

0 TI_Electronics over 7 years ago in reply to Ramesh Khanna

Intellectual 345 points

Out A is used to directly drive MOSFET. Flyback converter is operating in CCM with an output power of 50W.

0 Ramesh Khanna over 7 years ago in reply to TI_Electronics

TI__Expert 7445 points

Hi Kamlesh,

For any single ended application , oscillator frequency is equal to output frequency. As flyback will be a single ended application thus its switching frequency will oscillator frequency that can go up to 1Mhz as highlighted in the datasheet.
Note for push-pull converter applications output frequency will be one-half the oscillator frequency.

If it addressed your question, please verify the post.

0 TI_Electronics over 7 years ago in reply to Ramesh Khanna

Intellectual 345 points

Sir,

Could you please explain configuration of UC1825 for single ended application? Does it require shorting of OUTA and OUTB pins?

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UC1825: Regarding usage of UC1825 for 1MHZ switching frequency CCM Flyback converter