DS1302 Maxim, DS1302 Datasheet - Page 2

• Manufacturer Part Number: DS1302
• Description: The DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar and 31 bytes of static RAM
• Manufacturer: Maxim

DETAILED DESCRIPTION
The DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar and 31 bytes of static RAM. It
communicates with a microprocessor via a simple serial interface. The real-time clock/calendar provides seconds,
minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for
months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or
12-hour format with an AM/PM indicator.
Interfacing the DS1302 with a microprocessor is simplified by using synchronous serial communication. Only three
wires are required to communicate with the clock/RAM: CE, I/O (data line), and SCLK (serial clock). Data can be
transferred to and from the clock/RAM 1 byte at a time or in a burst of up to 31 bytes. The DS1302 is designed to
operate on very low power and retain data and clock information on less than 1μW.
The DS1302 is the successor to the DS1202. In addition to the basic timekeeping functions of the DS1202, the
DS1302 has the additional features of dual power pins for primary and backup power supplies, programmable
trickle charger for V
OPERATION
Figure 1 shows the main elements of the serial timekeeper: shift register, control logic, oscillator, real-time clock,
and RAM.
TYPICAL OPERATING CIRCUIT
CPU
V
CC
CC1
, and seven additional bytes of scratchpad memory.
I/O
SCLK
CE
X1
DS1302
GND
X2
V
V
CC2
CC1
V
CC
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