pcf8564a NXP Semiconductors, pcf8564a Datasheet - Page 5

• Manufacturer Part Number: pcf8564a
• Description: Real Time Clock And Calendar
• Manufacturer: NXP Semiconductors

NXP Semiconductors
8. Functional description
PCF8564A_1
Product data sheet
8.1 CLKOUT output
The PCF8564A contains sixteen 8-bit registers with an auto-incrementing address
register, an on-chip 32.768 kHz oscillator with integrated capacitors, a frequency divider
which provides the source clock for the RTC, a programmable clock output, a timer, a
voltage low detector, and a 400 kHz I
All sixteen registers (see
although not all bits are implemented. The first two registers (memory address 00h and
01h) are used as control and/or status registers. The addresses 02h through 08h are used
as counters for the clock function (seconds up to years counters). Address locations 09h
through 0Ch contain alarm registers which define the conditions for an alarm. Address
0Dh controls the CLKOUT output frequency. 0Eh and 0Fh are the timer control and timer
registers, respectively.
The seconds, minutes, hours, days, weekdays, months, years, as well as the minute
alarm, hour alarm, day alarm, and weekday alarm registers are all coded in BCD format.
A programmable square wave is available at the CLKOUT pin. Frequencies of 32.768 kHz,
1.024 kHz, 32 Hz and 1 Hz can be generated for use as a system clock, microcontroller
clock, input to a charge pump, or for calibration of the oscillator. CLKOUT is a CMOS
push-pull output, and if disabled it becomes logic 0.
Rev. 1 — 8 October 2009
Table
4) are designed as addressable 8-bit parallel registers
2
C-bus interface.
Real time clock and calendar
PCF8564A
© NXP B.V. 2009. All rights reserved.
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