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5 Application Reference

Fig 19 Typical Application diagram

5.1 Crystal frequency adjustment

Method 1: Fixed OSCI capacitor — By evaluating the average capacitance

necessary for the application layout a fixed capacitor can be used. The frequency is

best measured via the 32.768 kHz signal available after power-on at the CLKOUT

pin. The frequency tolerance depends on the quartz crystal tolerance, the capacitor

tolerance and the device-to-device tolerance (on average ±5 × 10−6).

Average deviations of ±5 minutes per year can be easily achieved.

Method 2: OSCI trimmer — The oscillator is tuned to the required accuracy by

adjusting a trimmer capacitor on pin OSCI and measuring the 32.768 kHz signal

available after power-on at the CLKOUT pin.

Method 3: OSCO output — Direct output measurement on pin OSCO (accounting for

test probe capacitance).

6 Package outline

HM8563