Questions about STPM066S

soulshine · ‎2026-01-15

Hi,

I am currently reviewing the use of the STPM066S. According to the documentation, it seems that one-time programming is required before voltage output is enabled. As I understand it, once the OTP region is written, the change is irreversible.

I have ordered the STPM066S evaluation board and some spare ICs.

My First question is: after programming and testing the initial settings, if I want to change the settings and test again, do I need to replace the IC with a new one each time? Or is there any way to reprogram or modify the OTP settings after the initial programming?

Second question,

There is a RSV TM bit in SPI MOSI data frame( DI[22] : Test Mode Flag). What is it? What can i test with this bit?

Can i test OTP area with this bit?

Last question,

There is a section labeled "(programming)" under the OTP reg. Could you please clarify what this means?

Peter BENSCH · ‎2026-03-05

Changing OTP settings
- Your understanding is correct: the STPM066S uses true one‑time programmable (OTP) memory.
- Once a bit is programmed from 0 to 1, it cannot be erased or changed back. If you need to test a different OTP configuration after you have already programmed a device, you must use a fresh IC.
- For evaluation, you should first validate all settings using the volatile RAM/SPI registers (shadow configuration) and only program OTP once you are confident with the final configuration.
RSV TM bit (DI[22])
- The RSV TM bit is a reserved test‑mode flag used only for internal factory / production test. It is not intended for application use and should always be kept at its default value in the SPI frame. It cannot be used to test or emulate the OTP area.
(programming) note in OTP table
- The “(programming)” label in the OTP register table indicates that this bit is programmed during the OTP programming sequence (e.g. vsel deciding between 5V...7V output). It does not mean it is re‑programmable in the field; it simply marks that this parameter is stored in OTP and becomes permanent once programmed.

Does this answer your questions?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

Peter BENSCH · ‎2026-03-05

Changing OTP settings
- Your understanding is correct: the STPM066S uses true one‑time programmable (OTP) memory.
- Once a bit is programmed from 0 to 1, it cannot be erased or changed back. If you need to test a different OTP configuration after you have already programmed a device, you must use a fresh IC.
- For evaluation, you should first validate all settings using the volatile RAM/SPI registers (shadow configuration) and only program OTP once you are confident with the final configuration.
RSV TM bit (DI[22])
- The RSV TM bit is a reserved test‑mode flag used only for internal factory / production test. It is not intended for application use and should always be kept at its default value in the SPI frame. It cannot be used to test or emulate the OTP area.
(programming) note in OTP table
- The “(programming)” label in the OTP register table indicates that this bit is programmed during the OTP programming sequence (e.g. vsel deciding between 5V...7V output). It does not mean it is re‑programmable in the field; it simply marks that this parameter is stored in OTP and becomes permanent once programmed.

Does this answer your questions?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

soulshine · ‎2026-03-09

Thanks you so much. It helps me a lot.