UCC24630: SR controller promotion selection for 130kHz max frequency and flyback application, need output short protection.

Cicely Tang

Part Number: UCC24630
Other Parts Discussed in Thread: UCC24612

Tool/software:

Hi Expert,

The customer has a sysc rectifier need, customer's topology is two-switch flyback in Air-condition outdoor unit power. And his max frequency is about 130kHz and second-rectifier mosfet's Rds(on) is about 7mΩ.

I have these question as below:

1、What's the hero product in SR product, and pls promote a suitable hero product to meet customer's spec? what's the main application EE?

2、Customer wonder if UCC24630/UCC24612 have the mosfet's Rds(on) limitation?

3、Can you teach me what's the different control mode's disadvantage and advantages at application, such as /Volt-second balancing/Vds sensing. Which mode is better?

Best regards,

Cicely

7 months ago

0 Cicely Tang 7 months ago

TI__Prodigy 730 points

Another question about the UCC24612-1;

How to calculate the Mosfet Rds(on) limitation? And why do it have a Rds(on) limitation?

0 Ulrich Goerke 7 months ago in reply to Cicely Tang

TI__Mastermind 40580 points

Hello Cicely,

Please see this paper on comparing the Volt-second method to the Vds-sensing method:
https://www.ti.com/lit/pdf/ssztce5

There is not enough information in your description of the customer's application to suggest the optimal SR controller.
Is the 2-switch flyback fixed frequency or variable frequency? Is it CCM flyback or DCM flyback?
UCC24630 is better for CCM-flyback SR, but not if the switching frequency varies rapidly. Only if fSW varies slowly.
See this previous E2E thread:
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1457931/ucc24630-is-there-any-other-5v-to-24v-output-flyback-more-suitable-for-use-in-variable-frequency

If it is DCM-flyback, UCC24612-2 can be used (with Rds(on) limitation) or the UCC24636 without limitation.

Regards,
Ulrich

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UCC24630: SR controller promotion selection for 130kHz max frequency and flyback application, need output short protection.