TPS40422: Could you review schematic for TPS40422?

Downey Kim

Expert 2675 points

Part Number: TPS40422
Other Parts Discussed in Thread: CSD87350Q5D, TPS40322

Hi TI experts,

My customer has requested a SCH review for TPS 40422. For external fet, CSD87350Q5D was applied.

Attached the schematic and inductor datasheet.

xcu_power_sch.pdf PG0077.801NLT.PDF

1. Ch1 is 1V, 7A for the core Vcc supply of Broadcom chips.

2. Ch2 is 5V, 5A for system supply.

Please check that the R, L, and C values applicable to the design specifications are appropriate.

Thanks,

Downey Kim.

over 3 years ago

0 Qian Chen over 3 years ago

TI__Mastermind 24075 points

Hi Downey,

Is PMBus needed for customer's application?

If not, I would suggest to use TPS40322 which has small size and low cost.

Thanks

Qian

0 Downey Kim over 3 years ago in reply to Qian Chen

Expert 2675 points

Hi Qian,

It is already made of PCB and cannot be changed.

Is there any problem with the circuit? or no problem?

Thanks,

Downey Kim.

0 Qian Chen over 3 years ago in reply to Downey Kim

TI__Mastermind 24075 points

Hi Downey,

Attached is the review.

Refer to equation (2) on datasheet.

Usually L/DCR should be equal to Rs*Cs, unless noise is coupled to Cs.

xcu_power_sch_reviewed.pdf

Thanks

Qian

0 Downey Kim over 3 years ago in reply to Qian Chen

Expert 2675 points

Hi Qian,

We did remove R220 (2.49kohm) and change C138 to 0.47uF.

Vout became 3.3V. What is the problem?

Please check it...

Thanks,

Downey Kim.

0 Qian Chen over 3 years ago in reply to Downey Kim

TI__Mastermind 24075 points

Hi Downey,

Can you measure FB pin voltage?

Also, can you provide Vout and SW waveform?

Thanks

Qian

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TPS40422: Could you review schematic for TPS40422?