PCF2123TS/1.118 NXP Semiconductors, PCF2123TS/1.118 Datasheet - Page 6

• Manufacturer Part Number: PCF2123TS/1.118
• Manufacturer: NXP Semiconductors

Specifications of PCF2123TS/1.118

• Bus Type: Serial (3-Wire, SPI)
• Package Type: TSSOP
• Operating Supply Voltage (max): 5.5V
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Mounting: Surface Mount
• Date Format: DW:DM:M:Y
• Time Format: HH:MM:SS
• Lead Free Status / RoHS Status: Compliant

NXP Semiconductors
8. Functional description
PCF2123
Product data sheet
8.1.1 Power consumption with respect to quartz series resistance
8.1 Low power operation
The PCF2123 contains 16 8-bit registers with an auto-incrementing address counter, an
on-chip 32.768 kHz oscillator with two integrated load capacitors, a frequency divider
which provides the source clock for the Real Time Clock (RTC), a programmable clock
output, and a 6.25 Mbit/s SPI-bus. An offset register allows fine tuning of the clock.
All 16 registers are designed as addressable 8-bit parallel registers although not all bits
are implemented.
Minimum power operation will be achieved by reducing the number and frequency of
switching signals inside the IC, i.e., low frequency timer clocks and a low frequency
CLKOUT will result in lower operating power. A second prime consideration is the series
resistance R
The series resistance acts as a loss element. Low R
further.
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The first two registers (memory address 00h and 01h) are used as control registers.
The memory addresses 02h through 08h are used as counters for the clock function
(seconds up to years). The registers Seconds, Minutes, Hours, Days, Weekdays,
Months, and Years are all coded in Binary Coded Decimal (BCD) format. When one of
the RTC registers is written or read the contents of all counters are frozen. Therefore,
faulty writing or reading of the clock and calendar during a carry condition is
prevented.
Addresses 09h through 0Ch define the alarm condition.
Address 0Dh defines the offset calibration.
Address 0Eh defines the clock out and timer mode.
Address registers 0Eh and 0Fh are used for the countdown timer function. The
countdown timer has four selectable source clocks allowing for countdown periods in
the range from 244 μs up to four hours. There are also two pre-defined timers which
can be used to generate an interrupt once per second or once per minute. These are
defined in register Control_2 (01h).
s
of the quartz used.
All information provided in this document is subject to legal disclaimers.
Rev. 03 — 5 October 2010
s
will reduce current consumption
SPI Real time clock/calendar
PCF2123
© NXP B.V. 2010. All rights reserved.
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