PCA2125 datasheet(3/36 Pages) NXP

3 / 36 page

PCA2125_1

Product data sheet

Rev. 01 — 28 July 2008

3 of 36

NXP Semiconductors

PCA2125

SPI Real-time clock/calendar

Pinning information

7.1 Pinning

7.2 Pin description

Functional description

The PCA2125 contains sixteen 8-bit registers with an auto-incrementing address register,

an on-chip 32.768 kHz oscillator with one integrated capacitor, a frequency divider which

provides the source clock for the Real-Time Clock (RTC), a programmable clock output,

and a 6 MHz SPI-bus.

All sixteen registers are designed as addressable 8-bit parallel registers although not all

bits are implemented:

Fig 2.

Pin conﬁguration for TSSOP14

PCA2125

OSCI

VDD

OSCO

CLKOUT

n.c.

INT

SCL

SDI

VSS

SDO

001aaf892

Table 3.

Pin description

Symbol

Description

OSCI

oscillator input

OSCO

oscillator output

n.c.

3, 4

not connected; do not connect and do not use as feed through; connect

to VDD if ﬂoating pins are not allowed

INT

interrupt output (open-drain; active LOW)

chip enable input (active HIGH) with 200 k

Ω pull-down resistor

VSS

ground

SDO

serial data output, push-pull

SDI

serial data input; might ﬂoat when CE inactive

SCL

serial clock input; might ﬂoat when CE inactive

n.c.

11, 12

not connected; do not connect and do not use as feed through; connect

to VDD if ﬂoating pins are not allowed

CLKOUT

clock output (open-drain)

VDD

supply voltage

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