UCC21222-Q1: Support 100% Duty cycle

Hi Scarlett,

To determine whether this device can support 100% duty cycle will depend on additional details of the design:

• Will both high side and low side need to support 100% duty cycle?
  • Could you give more details this 100% duty cycle operation?
• Will both high side and low side have its own isolated bias supply or will they use a bootstrap circuit?

Let us know if there's any questions.

Best regards,

Andy Robles

Hi Andy, 

- Buck circuit input voltage is close to output, therefore I think only only high side needs 100% cycle,

- Customer can use isolated bias supply. Bootstrap circuit cannot achieve 100% since need time to charge the cap, right?

Thanks,

Scarlett

Hi, Scarlet,

That is correct. We would need to calculate it, but unless it goes high for hundreds Of milliseconds or more, the bootstrap should work. 

are they having problems with an existing circuit, or just working on a new design?

Best regards,

Don

Hi Don,

Thanks for your quick reply. It is a new design. Customer needs a buck circuit with Input voltage around 14V and output around 12V, since both input and output varies, for worst case customer is considering 100% duty which when input very close to output. Customer need dual channel iso driver since control on different GND. 

Thanks,

Scarlett