Datasheet

Philips Semiconductors
PCF8563
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Product data Rev. 04 — 12 March 2004 21 of 30
9397 750 12999
© Koninklijke Philips Electronics N.V. 2004. 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 ±5 × 10
−6
). Average deviations of ±5 minutes per year can be easily
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).