This application note investigates the power consumption during the operation of a typical application which puts the MCU (ST7Lite0) in HALT mode and wakes it up at regular intervals by an external interrupt generated by an active RC circuit. It also lists the typical consumption values and the parameters on which this consumption depends. The internal Pull up (Rpu) of an I/O port is used for the active RC to minimise the number of external components. The value of the Rpu varies with the supply voltage of the MCU and with temperature. Externally, only one capacitor is used. The ST7LITE0 clock source is configured by option byte to be internal RC with PLL*8. All measurements are taken at ambient temperature.
The document investigates the power consumption of a typical application where the ST7LITEO MCU is placed in HALT mode and woken up at regular intervals by an external interrupt generated by an active RC circuit. It analyzes how consumption depends on parameters such as supply voltage, temperature, and capacitor values, utilizing the internal pull-up resistor to minimize external components.
A software delay of 294 cycles must be inserted before putting the MCU in HALT again.
At 3.6V, the MCU stays in Halt mode for a duration of 72.00 ms.
The best result is achieved with a 1uF capacitor value and using an internal pullup.