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2015-12-0001

PT0280-8

12/11/15

8

PT7C43390/43390C

Real-time Clock Module

Functional Description

1. Overview of Functions

1.1. Clock function

CPU can read or write data including the year (last two digits), month, date, day, hour, minute, and second. Any (two-digit) year

that is a multiple of 4 is treated as a leap year and calculated automatically as such until the year 2099.

1.2. Alarm function

This device has two alarm system (Alarm 1 and Alarm 2) that outputs interrupt signals from INT1 pin or INT2 pin to CPU when

the date, day of the week, hour, minute or second correspond to the setting. Each of them may output interrupt signal separately at

a specified time. The alarm may be selectable between on and off for matching alarm or repeating alarm.

1.3. Programmable square wave output

For PT7C43390, square wave output at pin 1or pin 5. Six frequencies are selectable: 1, 2, 4, 8, 16, 32768 Hz.

1.4. Interface with CPU

PT7C43390: I

1.5. Calibration function

With the calibration bits properly set, the accuracy can be improved to better than ±2 ppm at 25°C.

2. Configuration of Data Communication

2.1. Data Communication

For data communication, the master device in the system generates a start condition for the IC. Next, the master devices transmits

4-bit device code “0110”, 3-bit command and 1-bit read / write command to the SDA line. After that, output or input is performed

from B7 of data. If data I/O has been completed, finish communication by inputting a stop condition to the IC. The master device

generates an acknowledgment signal for every 1-byte. Regarding details refer to "I

0

Device Code

Command

1

1

0

C2

C1

C0

R/W

B7

B6

B5

B4

B3

B2

B1

B0

1-byte data

Read/Write bit

STA

Start condition

ACK

Acknowledgment bit

ACK

Stop condition

STP