Datasheet

PCF8563 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 10 — 3 April 2012 36 of 50
NXP Semiconductors
PCF8563
Real-time clock/calendar
14. Application information
14.1 Quartz frequency adjustment
14.1.1 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 ppm). Average deviations of 5 minutes per year can be easily achieved.
14.1.2 Method 2: OSCI trimmer
Using the 32.768 kHz signal available after power-on at pin CLKOUT, fast setting of a
trimmer is possible.
14.1.3 Method 3: OSCO output
Direct measurement of OSCO out (accounting for test probe capacitance).
Fig 29. Application diagram
mgm665
SCL
SDA
V
SS
OSCI
OSCO
CLOCK CALENDAR
PCF8563
SDA
SCL
MASTER
TRANSMITTER/
RECEIVER
V
DD
V
DD
SDA SCL
RR
V
DD
(I
2
C-bus)
R: pull-up resistor
R =
1 F
t
r
C
b
100 nF