1

®

FN1547.8

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

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CDP68HC68T1

CMOS Serial Real-Time Clock With RAM

and Power Sense/Control

The CDP68HC68T1 Real-Time Clock provides a

time/calendar function, a 32 byte static RAM, and a 3 wire

Serial Peripheral Interface (SPI Bus). The primary function of

the clock is to divide down a frequency input that can be

supplied by the on-board oscillator in conjunction with an

external crystal or by an external clock source. The internal

oscillator can operate with a 32kHz, 1MHz, 2MHz, or 4MHz

crystal. An external clock source with a 32kHz, 1MHz, 2MHz,

4MHz, 50Hz or 60Hz frequency can be used to drive the

CDP68HC68T1. The time registers hold seconds, minutes,

and hours, while the calendar registers hold day-of-week,

date, month, and year information. The data is stored in BCD

format. In addition, 12 or 24 hour operation can be selected.

In 12 hour mode, an AM/PM indicator is provided. The T1

has a programmable output which can provide one of seven

outputs for use elsewhere in the system.

Computer handshaking is controlled with a “wired-OR” interrupt

output. The interrupt can be programmed to provide a signal as

the result of:

1. An alarm programmed to occur at a predetermined

combination of seconds, minutes, and hours.

2. One of 15 periodic interrupts ranging from sub-second to

once per day frequency.

used for external power control. The CPUR output is

available to reset the processor under power-down

conditions. CPUR is enabled under software control and

can also be activated via the CDP68HC68T1’s watchdog. If

enabled, the watchdog requires a periodic toggle of the CE

pin without a serial transfer.

Features

• SPI (Serial Peripheral Interface)

• Full Clock Features

- Seconds, Minutes, Hours (12/24, AM/PM), Day of

Week, Date, Month, Year (0 to 99), Automatic Leap Year

• 32 Wordx8-Bit RAM

• Seconds, Minutes, Hours Alarm

• Automatic Power Loss Detection

• Low Minimum Standby (Timekeeping) Voltage . . . . . 2.2V

• Selectable Crystal or 50/60Hz Line Input

• Buffered Clock Output

• Battery Input Pin that Powers Oscillator and also

• Three Independent Interrupt Modes

-Alarm

- Periodic

- Power-Down Sense

• Pb-Free Available (RoHS Compliant)

Pinouts

CDP68HC68T1

(16 LD PDIP, SOIC)

TOP VIEW

CDP68HC68T1

(20 LD SOIC)

TOP VIEW

9

10

11

12

13

14

16

15

8

7

6

5

4

3

2

1

CLKOUT

CPUR

INT

SCK

MOSI

MISO

CE

XTAL IN

XTAL OUT

LINE

POR

PSE

11

12

13

14

15

16

17

18

20

19

10

9

8

7

6

5

4

3

2

1

CLK OUT

CPUR

INT

NC

SCK

MOSI

CE

MISO

PSE

VDD

XTAL IN

NC

XTAL OUT

NC

NC

LINE

POR

Data Sheet

October 29, 2007