UCC28910: Small output current

Kuramochi Tadahiko

Guru 28715 points

Part Number: UCC28910
Other Parts Discussed in Thread: UCC28C42

Hi,

My customer is considering using UCC28910, the load current is 40mA(max).

In this case, Lp(min) is too large as below;

They would like to reduce this inductance.

Should the dummy load be located?

Or, is there any solution else?

Best Regards,

Kuramochi

Best Regards,

Kuramochi

over 4 years ago

0 Yunsheng Qu over 4 years ago

TI__Genius 9790 points

Hi, Tadahiko

I've forward your request to expert, please wait for the reply.

0 Kuramochi Tadahiko over 4 years ago in reply to Yunsheng Qu

Guru 28715 points

Hi Qu-san,

How is this progress?

Best Regards,

Kuramochi

0 Mike O' over 4 years ago in reply to Kuramochi Tadahiko

TI__Guru* 85446 points

Hello,

The tool calculates Lp based on maximum switching frequency , power and energy the design needs.

If they want to reduce the inductance try running the design at higher switching frequency.

A pre-load resistor is need so the design stay in regulation under no load conditions. Generally 2 mA of preload is enough.

Regards,

0 Kuramochi Tadahiko over 4 years ago in reply to Mike O'

Guru 28715 points

Mike-san,

Thank you for your help.

We are setting fsw(max) to 105kHz limited by the specification, so we can't rise frequency anymore as attached.

8865.SLUC503B_UCC28910 Design Calculator.xlsx

Is there any solution to reduce inductance?

Best Regards,

Kuramochi

0 Mike O' over 4 years ago in reply to Kuramochi Tadahiko

TI__Guru* 85446 points

Hello,

You could go to a fixed frequency flyback controller that operates at higher switching frequency like the UCC28C42. The device will operate up to 1 Mhz.

If you do decide to use the UCC28C42 and have questions. Please repost a new thread to the e2e so the appropriate applications engineer can help you.

Regards,

Mike

0 Kuramochi Tadahiko over 4 years ago in reply to Mike O'

Guru 28715 points

Hi Mike-san,

Thank you for your help.

The actual maximum current is 40mA on the customer's circuit.

However, the inductance can be reduced if over 40mA current is allowed.

Is my understanding correct?

Best Regards,

Kuramochi

0 Mike O' over 4 years ago in reply to Kuramochi Tadahiko

TI__Guru* 85446 points

Hello,

V = Lpm*di/dt

If you have a fixed input voltage increase current for the same dt, you can reduce Lpm.

However, this is designing the converter for a higher power level.

Regards,

Power management

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UCC28910: Small output current