AN673 Datasheet PDF - STMicroelectronics

INTRODUCTION
In many cases a 32kHz crystal is chosen for the oscillator of the ST62 microcontroller in order to achieve the minimum current consumption in the application.
This note provides a technique for minimising the current consumption when using a crystal oscillator at this frequency.
The note should be read in conjunction with Application Note AN670 - Oscillator Selection for the ST62.