PCF2128 Datasheet, PDF (1/10 Pages) NXP Semiconductors – Integrated RTC / TCXO / Crystal

PCF2128
Integrated RTC / TCXO / Crystal
Rev. 00.03 — 4 June 2007
Preliminary [short] data sheet
1. General description
The PCF2128 is a ready to run CMOS real time clock/calendar with an integrated
temperature compensated crystal oscillator (TCXO). In timekeeping applications the high
accuracy of the PCF2128 allows it to be used as a replacement for costly and higher
powered long wave receivers or GPS receivers. A programmable battery switch-over
circuit enables an uninterruptible power supply and consequently continuous timekeeping.
The PCF2128 additionally features 512 bytes of general purpose RAM, a programmable
watchdog, a time stamp facility and a voltage monitoring facility. Programming is possible
using either an SPI or an I²C-bus interface.
2. Features
„ Integration of a 32.768 kHz quartz
„ 512 bytes of general purpose static
crystal in the same package as the RTC RAM
„ temperature compensated crystal
„ 1 second or 1 minute interrupt output
oscillator (TCXO) with integrated
capacitors.
„ accuracy:
„ oscillator stop detection
typically 3 ppm from−20 °C to +70 °C,
typically 5 ppm from −40 °C to +85 °C
„ provides year, month, day, weekday, „ two line bi-directional 1 MHz fast mode
hours, minutes and seconds
plus I²C interface
„ programmable alarm function with
„ timestamp input
interrupt capability
„ programmable countdown timer with „ power-on reset
interrupt capability
„ programmable watchdog timer with
„ 3 line SPI interface with separate data
interrupt and reset capability
input and output (maximum speed
6.5 Mbits/s)
„ timestamp function with interrupt
„ programmable square wave output pin
capability
„ battery backup input pin and switch-over „ I²C-bus slave address: read A3H and
circuitry
write A2H
„ extra power fail detection with input and „ clock operating voltage: <tbd> to 5.5 V
output pins
„ battery low detection
„ low backup current; typical 0.95 μA at
„ battery backed output voltage pin
V_DD = 3.0 V and T_amb = 25 °C
„ selectable I²C and SPI interface