PCF8563
NXP Semiconductors
Real-time clock/calendar
14. Application information
V
DD
SDA
SCL
MASTER
TRANSMITTER/
RECEIVER
1 F
100 nF
V
DD
SCL
SDA
CLOCK CALENDAR
OSCI
PCF8563
V
R
DD
OSCO
V
SS
R
R: pull-up resistor
t
r
R =
C
b
SDA SCL
mgm665
2
(I C-bus)
Fig 29. Application diagram
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).
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 [ NXP ]
