Linux/AM5728: VDD_SD voltage change

WTMEC_Will Hsu

Expert 2620 points

Part Number: AM5728
Other Parts Discussed in Thread: TMDSEVM572X,

Tool/software: Linux

Hi TI Team,
Why does VDD_SD voltage change form 3.3V to 2.9V on TMDSEVM572X ?

Do you have any concern about the voltage ?

Hardware : AM572x Evaluation Module / TMDSEVM572X (A3)
Software : PROCESSOR-SDK-LINUX-AM57X 03_02_00_05

By Will Hsu

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

Please see this post by Ahmad: e2e.ti.com/.../2031751

0 WTMEC_Will Hsu over 9 years ago in reply to Biser Gatchev-XID

Expert 2620 points

Thanks for your prompt response.

0 WTMEC_Will Hsu over 9 years ago in reply to WTMEC_Will Hsu

Expert 2620 points

Hi Biser,

The MMC driver in u-boot is setting the VDDSHV8 line to 3.0V intentionally.

But vddshv8 voltage is form 3.135V to 3.465V.

I'm confused.

Can you give me some suggestions?

Thanks.

SDK: ti-processor-sdk-linux-am57xx-evm-03.02.00.05

0 WTMEC_Will Hsu over 9 years ago

Expert 2620 points

Part Number: AM5728

Tool/software: Linux

Hi TI Team,

The MMC driver in u-boot is setting the VDDSHV8 line to 3.0V intentionally.

But vddshv8 voltage is form 3.135V to 3.465V.

I'm confused.

Can you give me some suggestions?

Thanks.

SDK: ti-processor-sdk-linux-am57xx-evm-03.02.00.05

EVM: AM572x Evaluation Module

0 Biser Gatchev-XID over 9 years ago in reply to WTMEC_Will Hsu

TI__Guru**** 393215 points

The MMC1 interface has PBIAS cell which also has to be programmed while changing the IO voltage. For a long time documentation stated that MMC1 I/O cells supply voltage can be either 1.8V or 3V. Hence both PBIAS and IO voltages were set to 3.0V.

However recently documentation has been fixed to indicate MMC1 I/O cells supply voltage can be either 1.8V or 3.3V. But this change has not been made to kernel yet.

Processors

Processors forum

Linux/AM5728: VDD_SD voltage change