PT7C43390 Datasheet, PDF (8/38 Pages) Pericom Semiconductor Corporation – Real-time Clock Module

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Functional Description
PT7C43390/43390C
Real-time Clock Module
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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: I²C bus interface.
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 "I²C-bus Serial Interface".
Start condition
Device Code
Command
Read/Write bit
Acknowledgment bit
STA
0
1
1
0
C2
C1
C0 R/W ACK
1-byte data
Stop condition
B7
B6
B5
B4
B3
B2
B1
B0 ACK STP
2015-12-0001
PT0280-8 12/11/15
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