The recommended power-up sequence is to first apply VDD (1.8V to 3.6V) and then VBAT (1.1V to 3.6V). This ensures proper initialization of the internal registers and oscillators.
To configure the AST1S31PUR for low-power mode, set the LPEN bit in the Control Register (CR) to 1. This will reduce the power consumption of the device. Additionally, you can also use the Power-Down mode by setting the PD bit in the CR to 1.
The internal oscillator on the AST1S31PUR has an accuracy of ±10% over the entire operating temperature range (-40°C to 85°C). This accuracy is sufficient for most applications, but if higher accuracy is required, an external crystal oscillator can be used.
Yes, the AST1S31PUR can be used as an RTC in battery-backed mode. The device has a built-in battery switch that allows the RTC to continue running even when the main power supply (VDD) is removed. The VBAT pin should be connected to a battery or a supercapacitor to maintain the RTC operation.
The AST1S31PUR can be reset by applying a low signal to the RST pin or by setting the SWRST bit in the Control Register (CR) to 1. The device will reset and restart its operation from the default values.
AST1S31PUR datasheet
by STMicroelectronics
