Datasheet

Low-Current, SPI-Compatible
Real-Time Clock
12 Maxim Integrated
DS1347
SPI-Compatible Serial Interface
Interface the device with a microcontroller using a serial,
4-wire, SPI interface. SPI is a synchronous bus for
address and data transfer, and is used with Motorola or
other microcontrollers that have an SPI port. Four con-
nections are required for the interface: DOUT (serial-
data out); DIN (serial-data in); SCLK (serial clock); and
CS (chip select). In an SPI application, the device acts
as a slave device and the microcontroller acts as the
master. CS is asserted low by the microcontroller to initi-
ate a transfer, and deasserted high to terminate a trans-
fer. DIN transfers input data from the microcontroller to
the device. DOUT transfers output data from the device
to the microcontroller. A shift clock, SCLK, is used to
synchronize data movement between the microcon-
troller and the device. SCLK, which is generated by the
Alarm Minutes Register (1Bh)
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
0 10 MINUTES MINUTES
0 1 1 1 1 1 1 1
Alarm Hours Register (1Dh)
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
AM/PM
12/24 0
20 HR
10 HR HOURS
1 0 1 1 1 1 1 1
Alarm Date Register (1Fh)
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
0 0 10 DATE DATE
0 0 1 1 1 1 1 1
Alarm Month Register (21h)
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
0 0 0 10 MO MONTH
0 0 0 1 1 1 1 1
Alarm Day Register (23h)
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
0 0 0 0 0 DAY
0 0 0 0 0 1 1 1
Alarm Year Register (25h)
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
10 YEAR YEAR
1 1 1 1 1 1 1 1