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AM625: TPS6521901 – Default LDO1_VSET NVM value and I2C programming sequence

Meera Shah
Prodigy 90 points

Part Number: AM625
Other Parts Discussed in Thread: TPS65219, TPS6521905

I am working with the TPS6521901 PMIC and would like clarification on the factory-programmed default configuration of LDO1, as well as the recommended I2C programming sequence.

From the TPS6521901 datasheet, the LDO1_VSET field (bits [5:0] in LDO1_VOUT) shows the reset value as “X – Default from NVM memory”, and the voltage selection table ranges from 0.6 V to 3.4 V. However, the datasheet does not explicitly state the default hex value programmed in NVM.

I also reviewed the TPS6521903 Technical Reference Manual, where the EEPROM Device Settings are clearly listed. In Table 2-5 (LDO Regulator Settings), the following defaults are shown:

  • LDO1_VSET = 0x36 → 3.3 V

  • LDO1_BYP_CONFIG = 0x1 → LDO1 configured in bypass mode

Since these values are listed under EEPROM Device Settings, I understand these to be the factory-programmed NVM (OTP/EEPROM) defaults for TPS6521903.

Additionally, I came across the following E2E thread discussing default LDO1 behavior (bypass mode) for other TPS65219 variants:
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1569166/tps65219-ldo1-default-configuration

Based on this, I would appreciate clarification on the following points specifically for TPS6521901:

  1. Can the TPS6521903 TRM EEPROM defaults (e.g., LDO1_VSET = 0x36, bypass enabled) be considered representative of the NVM defaults for TPS6521901 as well, or are these values variant-specific?

  2. For TPS6521901:

    • Is LDO1 configured in bypass mode by default?

    • What is the factory-programmed default value of LDO1_VSET?

  3. Are these NVM defaults consistent across TPS6521901 silicon revisions, or should software always read back the registers at boot to determine the active configuration?

  4. Once the PMIC is available on hardware, what is the recommended I2C sequence to configure LDO1?

    • Is a password/unlock write required before modifying LDO1_VOUT?

    • Is it safe to change LDO1 voltage during normal operation, or should it only be updated during initialization?