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LP87745-Q1: Writing to Register to change BUCK output voltage values

Part Number: LP87745-Q1
Other Parts Discussed in Thread: IWR6843

Hello Community,

I am working with the custom board where LP87745 is interfaced with IWR6843. With SPI communication I am able to read all the user register values.

Now I want to change the BUCK output voltage values by changing BUCKn_VSET value. 

I read that by default these registers are locked and hence the user must write 0X9B into REGISTER_LOCK Register to unlock the register which is at address 0x0A and then I would be able to change the BUCKn_VSET  value in BUCKn_VOUT register which is at 0x12, 0x13, 0x14.

But after writing 0x9B into REGISTER_LOCK register I don't see a change in REGISTER_LOCK_STATUS bit, it is still 1h (Registers are locked). I read this register after writing into it.

I was expecting it when I write 0x9B into REGISTER_LOCK and when I later read it, it should show value as 0x00 instead of 0x01. 

This means registers are still locked and hence I am not able to change BUCKn_VSET  values in BUCK registers.

Please let me know what I might be missing here, or how I could correctly write into user registers.

Regards,

Neil