PCF8583 Datasheet, PDF (21/28 Pages) NXP Semiconductors – Clock/calendar with 240 x 8-bit RAM

Philips Semiconductors
Clock/calendar with 240 × 8-bit RAM
Product specification
PCF8583
handbook, full pagewidth
PROTOCOL
START
CONDITION
(S)
BIT 7
MSB
(A7)
BIT 6
(A6)
t _SU;STA
t _LOW t _HIGH
1 / f _SCL
SCL
t _BUF
tr
tf
SDA
BIT 0
LSB
(R/W)
ACKNOWLEDGE
(A)
STOP
CONDITION
(P)
t _HD;STA
t _SU;DAT
t _HD;DAT
t _VD;DAT
MBD820
t _SU;STO
Fig.21 I²C-bus timing diagram; rise and fall times refer to V_IL and V_IH.
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 1 Hz signal
available after power-on at the interrupt output (pin 7).
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
achieved.
14.1.2 METHOD 2: OSCI TRIMMER
Using the alarm function (via the I²C-bus) a signal faster
than 1 Hz can be generated at the interrupt output for fast
setting of a trimmer.
Procedure:
• Power-on
• Initialization (alarm functions).
Routine:
• Set clock to time T and set alarm to time T + dT
• At time T + dT (interrupt) repeat routine.
14.1.3 METHOD 3:
Direct measurement of OSC out (accounting for test probe
capacitance).
The PCF8583 slave address has a fixed combination 1010
as group 1.
1997 Jul 15
21