Philips Semiconductors

PCA8565

Real time clock/calender

Product data

Rev. 01 — 31 March 2003

20 of 26

9397 750 10695

© Koninklijke Philips Electronics N.V. 2003. All rights reserved.

13.1 Quartz frequency adjustment

13.1.1

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 pin CLKOUT. The frequency tolerance depends on the

quartz crystal tolerance, the capacitor tolerance and the device-to-device tolerance

(on average

achieved.

13.1.2

Method 2: OSCI trimmer

Using the 32.768 kHz signal available after power-on at pin CLKOUT, fast setting of a

trimmer is possible.

13.1.3

Method 3: OSCO output

Direct measurement of OSCO out (accounting for test probe capacitance).