2024-08-08 09:02 AM
I have a small micro that needs to run before the MP157 is active. The voltage coming gin is 5V, but I need 3.3V. Is there an always-on LDO in the STPMIC1 for such purpose? I assume the internal LDO is not te be used?
Do I need to program the voltage of the LDO or is it set by default to 3.3V
Regards
Solved! Go to Solution.
2024-08-09 01:06 AM - edited 2024-08-09 01:07 AM
on STPMIC1A, you could use Buck3 which is started at 3.3V few tens of ms before the MP157 is out of reset and maintained on every modes including Standby. If you need more time, you could maintain the NRST low form your small MCU the time you need.
During operation of STM32MP15x, Buck3 is usually defined as 'no power cycle on NRST' within TF-A in our SW deliveries (e.g. Buck3 kept powered even when watchdog reset occurs after TF-A starts).
Obviously, a platform shutdown requesting an STPMIC1 power-off will make the Buck3 OFF as well.
Regards.
2024-08-09 12:30 AM
Hi,
version of STPMIC1? A, B or...?
To have the 3.3V @Rank1 you need to program (one time, output voltage and Rank#) the LDO# in the NVM content so it will start at turn ON phase.
The STPMIC1 I²C programming guide - Application note
Regards
Vincenzo
2024-08-09 01:06 AM - edited 2024-08-09 01:07 AM
on STPMIC1A, you could use Buck3 which is started at 3.3V few tens of ms before the MP157 is out of reset and maintained on every modes including Standby. If you need more time, you could maintain the NRST low form your small MCU the time you need.
During operation of STM32MP15x, Buck3 is usually defined as 'no power cycle on NRST' within TF-A in our SW deliveries (e.g. Buck3 kept powered even when watchdog reset occurs after TF-A starts).
Obviously, a platform shutdown requesting an STPMIC1 power-off will make the Buck3 OFF as well.
Regards.
2024-08-11 12:04 AM
Thanks for the note:
I measured the -DK2 and the behavior of BUCK3, LDO2 etc and indeed the STPMIC1A is 3.3V and stable and always on. The LDO e.a. are affected when reset occurs.
Tnx
2024-08-11 09:23 PM
Hi roland van straten,
you need to program the below address, see STPMIC1 DS rev.10 @page83
set bit to 1 active mask reset option for selected LDO for next
reset power-cycle. It is a single shot option and then register is reset to default
Regards
Vincenzo