TPS57140-Q1: How to calculate the dummy load resistor value?

shihui xu

Part Number: TPS57140-Q1

Tool/software:

We want to solve the low dropout operation with light load problem of TPS57140-Q1.

Could you tell me how to calculate the dummy load resistor value? I saw the solutions in SLVA547A, but it only give the value about 3.3V/5V output.

Our vout is 9.47V, and the minimum input is 10.4V, Fsw 2.2MHz.

Would lower the fsw also help?

4 months ago

0 Dino Maslic 4 months ago

TI__Expert 5610 points

Hi Shihui,

I'll talk to my team and get back to you regarding this.

Thanks,

Dino

0 shihui xu 4 months ago in reply to Dino Maslic

Prodigy 100 points

Hi Dino,

Any update?

0 Dino Maslic 4 months ago in reply to shihui xu

TI__Expert 5610 points

Hi Shihui,

Still working on this, will get back to you soon.

Thanks,

Dino

0 Dino Maslic 4 months ago in reply to Dino Maslic

TI__Expert 5610 points

Hi Shihui,

There is no defined equation on how to calculate this value unfortunately. Your minimum input voltage is about 900mV above your VOUT, to have some margin I looked at the graphs values at 600mV above VOUT, and the load resistor they were using was about 6-7mA of load, to be conservative you could use a 10mA load on your application. Think this could work.

Thanks,

Dino

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TPS57140-Q1: How to calculate the dummy load resistor value?