DS14285/DS14287

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ORDERING INFORMATION

DS14285

RTC Chip; 24-pin DIP

DS14285N

RTC Chip; 24-pin DIP; Industrial Temp Range

DS14285S

RTC Chip; 24-pin SOIC

DS14285SN

RTC Chip; 24-pin SOIC; Industrial Temp Range

DS14285Q

RTC Chip; 28-pin PLCC

DS14285QN

RTC Chip; 28-pin PLCC; Industrial Temp Range

DS14287

RTC Module; 24-pin DIP

PIN DESCRIPTION

AD0-AD7

- Multiplexed Address/Data Bus

NC

- No Connection

MOT

- Bus Type Select (DS14285Q only)

CS

- Chip Select

AS

- Address Strobe

- Read/Write Input

DS

- Data Strobe

RESET

- Reset Input

IRQ

- Interrupt Request Output

SQW

- Square Wave Output

- +5V Supply

GND

- Ground

- RAM Power Supply Output

CEI

- RAM Chip Enable In

CEO

- RAM Chip Enable Out

X1, X2

- 32.768 kHz Crystal Connections

- +3V Battery Input

DESCRIPTION

The DS14285/DS14287 Real Time Clock with NVRAM Control provides the industry standard DS1287

clock function with the additional feature of providing nonvolatile control for an external SRAM.

Functions include a nonvolatile time-of-day clock, alarm, 100-year calendar, programmable interrupt,

square wave generator, and 114 bytes of nonvolatile static RAM. For the DS14287 a lithium energy

source, quartz crystal, and write protection circuitry are contained within a 24-pin dual in-line package.

The DS14285 requires an external quartz crystal connected to the X1 and X2 pins as well as an external

to the DS14285 via pins 1 and 2 (X1, X2). The crystal selected for use should have a specified load

please consult Application Note 58, “Crystal Considerations with Dallas Real-time Clocks.”

The DS14285/DS14287 uses its backup energy source and battery-backup controller to make a standard

CMOS static RAM nonvolatile during power-fail conditions. During power fail, the DS14285/DS14287

battery.