AM5728: 3.3V supply for peripheral devices

Thariq CP

Part Number: AM5728
Other Parts Discussed in Thread: TPS54531, TMDSEVM572X, TPS22990, TPS53319

Hi,

We are designing a card using TMDSEVM572x as our reference, with AM5728 SoC. The processor I/O supply used is VDD_3v3, generated from 12V DC through TPS54531 and the load switch used on the EVM. Since the load on 3V3 is higher in our application, we are using a second TPS54531 regulator to generate 3V3 (PS_3V3_2) from the same 12V DC input.

If we use PS_3V3_2 to power up external modules connected to the processor (on PCIe, USB, VIN3A, UART, etc), do we require a level translator to interface these signals? It is observed that the EVM uses VDD_3V3 as supply for all the devices including Ethernet PHY, audio codec, etc.

The digital Ground plane is common for the board and the modules.

Regards,

Thariq

over 5 years ago

0 kcastille over 5 years ago

TI__Guru 54987 points

Thariq,

You need to be careful powering other components using a different 3.3V supply. You may have IO contention during power up if those two supplies ramp at different rates. We recommend you follow the EVM/IDK designs as closely as possible.

Regards,
Kyle

0 Thariq CP over 5 years ago in reply to kcastille

Intellectual 560 points

Hi Kyle,

Thank you for providing the information. In that case can we use a regulator and load-switch with higher current rating for 3V3- like TPS53319 & TPS22990?

Regards,

Thariq C P

0 Bill McCracken over 5 years ago in reply to Thariq CP

TI__Expert 7065 points

Yes, you can use a higher current rated Converter & load switch. Please be careful to double-check the new component's turn-on delays & rise time ramping times to ensure system power up & down sequences align with SoC voltage domain recommendations.

Bill

0 Thariq CP over 5 years ago in reply to Bill McCracken

Intellectual 560 points

We are using a CT capacitor of 10kpF for TPS22990, which corresponds to a rise time of 404.8us at VIN of 3V3 according to the datasheet.

Thariq

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AM5728: 3.3V supply for peripheral devices