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100101
FEATURES
32-bit counter
Two-wire serial interface
Automatic power-fail detect and switch
circuitry
Power-fail reset output
Low-voltage oscillator operation (1.3V min.)
Trickle charge capability
Underwriters Laboratory (UL) recognized
ORDERING INFORMATION
DS1672X-X
2
2.0V Operation
3
3.0V Operation
33 3.3V Operation
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S
U
8-Pin DIP
8-Pin SOIC
8-Pin μSOP
PIN ASSIGNMENT
http://www.maxim-ic.com/TechSupport/PackInfo.htmPIN DESCRIPTION
V
CC,
V
BACKUP
GND
X1, X2
SCL
SDA
RST
- Power Supply Inputs
- Ground
- 32.768kHz Crystal Pins
- Serial Clock
- Serial Data
- Reset Output
DESCRIPTION
The DS1672 low-voltage serial timekeeping chip 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 the status of V
CC
. When an out-of-tolerance condition occurs, an internal
power-fail signal is generated that forces the reset to the active state. When V
CC
returns to an in-tolerance
condition, the reset signal is kept in the active state for 250ms 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
1
2
3
4
8
7
6
5
V
CC
RST
SCL
SDA
X1
X2
V
BACKUP
GND
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