DS1315

2 of 21

PIN DESCRIPTION

X1, X2

- 32.768 kHz Crystal Connection

WE

- Write Enable

BAT1

- Battery 1 Input

GND

- Ground

D

- Data Input

Q

- Data Output

- ROM/RAM Mode Select

CEO

- Chip Enable Output

CEI

- Chip Enable Input

OE

- Output Enable

RST

- Reset

BAT2

- Battery 2 Input

- Switched Supply Output

- Power Supply Input

DESCRIPTION

The DS1315 Phantom Time Chip is a combination of a CMOS timekeeper and a nonvolatile memory

controller. In the absence of power, an external battery maintains the timekeeping operation and provides

power for a CMOS static RAM. The watch keeps track of hundredths of seconds, seconds, minutes,

hours, day, date, month, and year information. The last day of the month is automatically adjusted for

months with less than 31 days, including leap year correction. The watch operates in one of two formats:

a 12-hour mode with an AM/PM indicator or a 24-hour mode. The nonvolatile controller supplies all the

necessary support circuitry to convert a CMOS RAM to a nonvolatile memory. The DS1315 can be

interfaced with either RAM or ROM without leaving gaps in memory.

OPERATION

The block diagram of Figure 1 illustrates the main elements of the Time Chip. The following paragraphs

describe the signals and functions.