This application note describes low-cost reset circuits for ST6 microcontrollers, including external reset circuitry and internal low voltage detector (LVD) reset circuitry, providing power-up and power-down monitoring, and delay power-on reset.
This document provides guidance on designing reset circuits for ST6 microcontrollers to ensure the device starts up in a known state. It details external hardware implementations, ranging from simple power-on reset circuits using RC components to advanced circuits with brown-out protection and power-down monitoring. The note also explains how to use the internal watchdog timer in conjunction with software loops to prevent malfunctions caused by noisy reset signals.
To guarantee that the device starts up in a known state, as the device may power-up in an unknown state if cells start operating at different voltage levels.
The simple circuit uses an external RC (resistor and capacitor) to generate the reset pulse.
It causes a reset whenever the supply voltage drops below the zener diode voltage plus the Vbe.