4.8.6 Functional Description

The SHDWC manages the main power supply. To do so, it is supplied with VDDBU and manages wake-up input pins and one output pin, SHDN.

A typical application connects the pin SHDN to the enable input of the device's power supply circuit. The wake-up inputs (WKUPn) connect to any push-buttons or signal that wake up the system.

The software is able to control the pin SHDN by writing the Control register (SHDW_CR) with the bit SHDW at 1. The shutdown is taken into account only two MD_SLCK cycles after the write of SHDW_CR. This register is password-protected and so the value written should contain the correct key for the command to be taken into account. As a result, the SHDN pin is driven low and the system should be powered down.

The SHDWC can also detect and debounce wake-up inputs to generate interrupts by configuring the Interrupt Enable and Interrupt Disable registers (SHDW_IER/SHDW_IDR) and by reading the Interrupt Status register (SHDW_ISR).

The SHDWC manages the LPM pin which is used to indicate to an external power supply that the drive of the system can be reduced. This pin can be configured to be automatically managed by software or by hardware.