TPS6594EVM: Using TPS6594111 to handle load issues

Honle Zhao

Part Number: TPS6594EVM

Tool/software:

Dears

Two power boards were designed using TPS659411 to supply power to the DSP core, BUCK1+BUCK2+BUCK3+BUCK4. Board A uses a 12 layer PCB design with capacitors placed on the bottom layer, while board B uses a 4-layer PCB design with capacitors placed on the top layer. The maximum load of board A can only reach 5.3A, and the maximum load of board B is 10A. With the same schematic, the IC uses default configuration parameters without modification. May I ask if the problem with board A is related to PCB design? Could you please provide some advice?

3 months ago

0 Jari Niemela13 3 months ago

TI__Genius 13850 points

Hi Honle,

Just recapturing info below.

Board A: output caps on bottom, 12 layer only 5.3 A

Board B: output caps on top, 4 layer up to 10 A

This is first time I'm hearing PCB stack-up could affect operation so I doubt that. PCB figures above are a little hard to read to how is the FB_B1 and FB_B2 connected on designs A and B? How you verify output current level? Have you measured PVIN_Bx looking similar under loading on both boards, I mean scope shot under loading?

There are quite many variables so we would need to understand is operating condition really the same or are we seeing some degradation somewhere else as well.

Br, Jari

0 Honle Zhao 3 months ago in reply to Jari Niemela13

Intellectual 630 points

Dears

The load is the same,It is the DSP core voltage,The 4-layer PCB is connected to the DSP motherboard using fly wires，Comparing two designs, only the PCB is different，When the current reaches 5.3A on the 12th layer, the output stops and the current becomes 0A

0 Jari Niemela13 2 months ago in reply to Honle Zhao

TI__Genius 13850 points

Hi Honle,

Please provide some measurements from input and output voltages since otherwise we are not making progress. Also better PCB layout figures would be preferred for review.

So bot h boards are measured when connected to DSP board with fly wires. And only Board A faces this shutdown issues in similar measurement case. Is input supply in both cases same?

Br, Jari

0 Honle Zhao 2 months ago in reply to Jari Niemela13

Intellectual 630 points

Dears

The input and output voltages are the same,it's just that the layout is different,There's no need to question this,pls help check layoutpic_of_PMIC.zip