ACE5372

Low Power Real-Time Clock (RTC)

VER 1.2

4

Functional Descriptions

Allocation of Internal Addresses

Internal

Address

Contents

Function

0H

Second Counter

Counting and storing seconds in BCD codes

1H

Minute Counter

Counting and storing minutes in BCD codes

2H

Hour Counter

Counting and storing hours in BCD codes

3H

Day of the Week Counter

Counting and storing days of the week in BCD codes

4H

Day Counter

Counting and storing days in BCD codes

5H

Month Counter

Counting and storing months in BCD codes

6H

Year Counter

Counting and storing years in BCD codes

7H

Time Trimming Register

Storing adjusting parameter and external select control of crystal

oscillator

8H

Alarm_A (Minute Register)

Storing minutes in Timer A

9H

Alarm_A (Hour Register)

Storing hours in Timer A

AH

Alarm_A (Day of the Week

Register)

Storing days of the week in Timer A

BH

Alarm_B (Minute Register)

Storing minutes in Timer B

CH

Alarm_B (Hour Register)

Storing hours in Timer B

DH

Alarm_B (Day of the Week

Register)

Storing days of the week in Timer B

EH

Control Register 1

Storing ring enable, interrupt output port select, and periodic

interrupt cycle select information

FH

Control Register 2

Storing time display select, interrupt and alarm signal, oscillator

halt sensing information

Calendar Counter

The ACE5372 can exchange from year to second (lower two bits) with CPU. When the lower two bits of

the year could be divided by 4, that year is leap year. It could automatically recognize the year between

2000 and 2099 and these data are stored separately in registers from 0H to 6H.

High Precision time Trimming function

The ACE5372 has an internal oscillation circuit capacitance CGND and CVDD so that an oscillation

circuit may be configured simply by externally connecting a crystal. The ACE5372 incorporates a time

trimming circuit (at internal address 7H) that adjusts gain or loss of the clock from the CPU up to

approx.±189ppm(±194ppm when 32.000KHz crystal is used) by approximately 3ppm steps to correct

discrepancy in oscillation frequency.

*Clock display is possible at much higher precision than conventional real-time clock while using a

crystal with broader fluctuation in precision.

* Even seasonal frequency fluctuation may be corrected by adjusting seasonal clock error.

For those systems that have temperature detection precision of clock, function may be increased by

correcting clock error according to temperature fluctuations.