STM32WBA55 VBAT PROBLEM

[YBAYR.1]

I have a project for a battery-powered clock using the STM32WBA55 chip. The battery is replaceable; the device can sit unused on a shelf for up to 4 months without the battery. Since the STM32WBA55 doesn't have VBAT or VRTC pins, how can I keep the backup recorder, time, and date active?

[TDK · Accepted solution]

You can power the device normally and use low-power modes to modulate power usage. Look at the Standby Retention low power mode and see if it can reduce power consumption enough. Put the main power on a GPIO pin so you know when it disappears in order to switch to a low-power mode.

Will require some minor design expertise to draw from battery power only when main power is not present.