CDP1879 Intersil Corporation, CDP1879 Datasheet

CDP1879

Manufacturer Part Number

CDP1879

Description

CMOS Real-Time Clock

Manufacturer

Intersil Corporation

Datasheet

1.CDP1879.pdf (18 pages)

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March 1997

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

http://www.intersil.com or 407-727-9207

Features

• CPU Interface for Use with General-Purpose

• Time Of Day/Calendar

• Reads Seconds, Minutes, Hours

• Reads Day of Month and Month

• Alarm Circuit With Seconds, Minutes or Hours

• Power Down Mode

• Separate Clock Output Selects 1 of 15 Square Wave

• Interrupt Output Activated By Clock Output and/or

• Date Integrity Sampling for Clock Rollover Eliminated

• On-Board Oscillator:

• Addressable in Memory Space or CDP1800 Series I/O

• Low Standby (Timekeeping) Voltage with External Clock

• Related Literature

Pinout

Microprocessors

Operation

Signals

Alarm Circuit

- Crystal Operation CDP1879 at 10V . . . . . . . 4.19MHz,

- Crystal Operation CDP1879C-1 at 5V . . . . . 4.19MHz,

- External Clock Operation at 10V or 5V. . . . 4.19MHz,

Mode

- AN7275, Guide to the Use of CD1879 and

CDP1879C1 Real Time Clock

POWER DOWN

CDP1879, CDP1879C-1 (PDIP, SBDIP)

IO/MEM

TPB/WR

RESET

TPA

INT

TOP VIEW

2.09MHz or 1.048MHz or 32kHz

2.09MHz, 1.048MHz or 32kHz

2.09MHz or 1.048MHz

Intersil Corporation 1999

XTAL

CLK

OUT

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

4-104

Description

The CDP1879 real-time clock supplies time and calendar information

from seconds to months in BCD format. It consists of 5 separately

addressable and programmable counters that divide down an oscillator

input. The clock input can have any one of 4 possible frequencies,

allowing ﬂexibility in the choice of crystal or external clock sources.

Using an external 32kHz clock source, timekeeping can be performed

down to 2.5V (see Standby (Timekeeping) Voltage Operation).

The device can be memory-mapped for use with any general-purpose

microprocessor and has the additional capability of operating in the

CDP1800 series input/output mode.

The real-time clock functions as a time-of-day/calendar with an alarm

capability that can be set for combinations of seconds, minutes or

hours. Alarm time is conﬁgured by loading alarm latches that activate

an interrupt output through a comparator when the counter and alarm

latch values are equal.

Fifteen selectable square-wave signals are available as a separate

clock output signal and can also activate the interrupt output. A status

control register determines the operational characteristics of the device,

by selecting the prescaler divisor and the clock output, and controls the

load and alarm functions.

A transparent “freeze” circuit preclude clock rollover during counter and

latch access times to assure stable and accurate values in the counters

and alarm latches.

The CDP1879 is functionally identical to the CDP1879C-1. The

CDP1879 has a recommended operating voltage range of 4V to 10.5V,

and the CDP1879C-1 has a recommended operating voltage range of

4V to 6.5V. The CDP1879 and the CDP1879C-1 are supplied in 24 lead

hermetic dual-in-line side-brazed ceramic packages (D sufﬁx) and 24

lead dual-in-line plastic packages (E sufﬁx

Ordering Information

CDP1879 Modes of Operation

Read

Write

Power Down

Interrupt

PDIP

SBDIP

OPERATION

PACKAGE

Burn-In

1. Seconds, minutes, hours, date and month counters

2. Status register to identify interrupt source

1. Control register to set device operation

2. Seconds, minutes, hours, date and month counters

3. Alarm latches for alarm time

1. Three-state interrupt output with active alarm or

2. Data bus and address inputs are “DON’T CARE”

1. Clock out as source

2. Alarm time as source

3. Either interrupt can occur during normal or power

-40

RANGE

+85

TEMP

clock out circuitry for wake-up control

down mode

C to

CDP1879C-1

CMOS Real-Time Clock

CDP1879CE1

CDP1879CD1

CDP1879CD1X

CDP1879,

FUNCTION

File Number

CDP1879E

10V

E24.6

D24.6

PKG.

1360.2

NO.

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