TPS25990: EFUSE PMBus Commands write issue.

Prem Kumar

Prodigy 110 points

Part Number: TPS25990

Hello Sir/Ma'am,

I am facing issue with writing into PMbus registers in the EFUSE.

First, I have disabled "Write Protection" by writing 0xA2 (MFR_WRITE_PROTECT) into the PMBus command 0xF8.

Then, I write into the 0x59 (VIN_UV_FLT) PMBus Command.

Then, when I read the Command 0x59, I am getting the Default value (0x8D).

But, when I write into the OPERATON (0x01) PMBus command to switch off, the device is switching off.

Why am I not able to write into VIN_UV_FLT even after disabling the write protection. I have tried writing into 0x57(VIN_OV_WARN) but the write operation is not happening.

over 1 year ago

0 Avishek Pal over 1 year ago

TI__Mastermind 38890 points

Hi Prem,

Thanks for reaching out. Could you please read this below register and share the data?

MFR_REVISION (9Bh, Block Read)

0 Prem Kumar over 1 year ago in reply to Avishek Pal

Prodigy 110 points

Hi Avishek,

The data in the register MFR_REVISION is 0x01

0 Avishek Pal over 1 year ago in reply to Prem Kumar

TI__Mastermind 38890 points

Hi Prem,

It seems to me surprising. I'd like to see the below results. Please help.

1) First read F8h register,

2) Write 0xA2h in the F8h

3) Read F8h register

Please make sure you are using write word protocol to change the data into 59h register.

0 Prem Kumar over 1 year ago in reply to Avishek Pal

Prodigy 110 points

Hi Avishek,
1) 0x00 in F8h register

2) Wrote 0xA2 into F8h

3) 0xA2 reflected in F8h register

I am writing into 59h in the same way I wrote into F8h. Is this correct or can you please briefly state the steps for write word protocol.

0 Avishek Pal over 1 year ago in reply to Prem Kumar

TI__Mastermind 38890 points

Hi Prem,

F8h is Read/Write Byte command.

59h is Read/Write Word command.

Word and Byte protocols are different.

Please see the PMBus specifications regarding the protocol details.

Specification Archives | PMBus

0 Prem Kumar over 1 year ago in reply to Avishek Pal

Prodigy 110 points

Can you please state the steps to make VIN_UV_FLT to be 6V i.e to write 0x4E into VIN_UV_FLT.

+1 Avishek Pal over 1 year ago in reply to Prem Kumar

TI__Mastermind 38890 points

Hi Prem,

Could you please refer to this FAQ? Please let me know if you still have any queries.

(5) [FAQ] TPS25990: How to program the non-volatile memory (NVM) in TPS25990 with a revised configuration file? - Power management forum - Power management - TI E2E support forums