TPS65131-Q1: PMP9780 design questions

Sherry Liang

Part Number: TPS65131-Q1
Other Parts Discussed in Thread: PMP9780, PMP

Dear team,

My customer uses PMP9780 reference design for their application, currently we have three questions as below,

1. Our inductor computation is as below. My application condition as below, VIN=3.3, VOUT=6V/-6V, I_load=80mA, and the Ripple factor is 0.2. Then L1=23.6uH, L2=75uH which is too large. Out recommendation is 4.7uH~6.8uH. Our device can't be used under small load current, for example, 80mA? If our device can, then how do I compute the inductor value? Is 10uH enough?

2. Do we have the efficiency of the charge pump design?

3. Below is our BOM, could you please tell me how do you determine the rating voltage of below capacitors?

Thanks & Best Regards,

Sherry

over 4 years ago

0 Liaqat Khan over 4 years ago

TI__Mastermind 18550 points

Hi Sherry,

We are busy with several other customer support items ahead of this one but will review your post by Tuesday my time and provide any feedback by then. Thank you for your patience.

Kind Regards,

Liaqat

+1 Liaqat Khan over 4 years ago in reply to Liaqat Khan

TI__Mastermind 18550 points

Hi Sherry,

1. Please use 4.7uH inductor: it should work well for light and heavy load.

2. All the measurement data is in the PMP reference design "Test Data" document that you can download at the link below. We do not have any other measured data for this design.

https://www.ti.com/lit/ug/tidu978/tidu978.pdf?ts=1628029850523&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FPMP9780

3. Voltage rating of the capacitors in an application is determined by measuring/calculating maximum possible voltage at the node where capacitor is used and then adding a comfortable margin. I suggest to stick with the same voltage rating as that used in the PMP9780 reference design and not deviate from it.

Kind Regards,

Liaqat

0 Sherry Liang over 4 years ago in reply to Liaqat Khan

TI__Genius 10255 points

Hi Liaqat,

Thanks for your help!

For the inductor, my customer wants to use 10uH because this inductor has stocks. 10uH should be also ok, right?

Thanks & Best Regards,

Sherry

0 Liaqat Khan over 4 years ago in reply to Sherry Liang

TI__Mastermind 18550 points

Hi Sherry,

10uH should be ok.

Kind Regards,

Liaqat

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TPS65131-Q1: PMP9780 design questions