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082800

FEATURES

32-bit counter

2-wire serial interface

Automatic power-fail detect and switch

circuitry

Power-fail reset output

Low-voltage oscillator operation (1.3V min.)

Trickle charge capability

ORDERING INFORMATION

DS1672X-X

2

2.0V operation

3

3.0V operation

33 3.3V operation

blank

8-pin DIP

S8-pin SOIC

U

8-pin µSOP

PIN ASSIGNMENT

PIN DESCRIPTION

- Power Supply Inputs

GND

- Ground

X1, X2

- 32.768 kHz crystal pins

SCL

- Serial clock

SDA

- Serial data

RST

- Reset output

DESCRIPTION

The DS1672 incorporates a 32-bit counter and power monitoring functions.

The 32-bit counter is

designed to count seconds and can be used to derive time of day, week, month, month, and year by using

a software algorithm. A precision temperature-compensated reference and comparator circuit monitors

is kept in the active state for 250 ms to allow the power supply and processor to stabilize.

OPERATION

The block diagram in Figure 1 shows the main elements of the DS1672. As shown, communications to

and from the DS1672 occur serially over a 2-wire bi-directional bus. The DS1672 operates as a slave

device on the serial bus. Access is obtained by implementing a START condition and providing a device

identification code followed by a register address. Subsequent registers can be accessed sequentially until

a STOP condition is executed.

DS1672

Low Voltage Serial Timekeeping Chip

PRELIMINARY

1

2

3

4

8

7

6

5

RST

SCL

SDA

X1

X2

GND