LA72680M
PS No.7955-20/21
I
2C BUS serial interface specification
(1) DATA TRANSFER MANUAL
This IC adopts control method(I2C-BUS) with serial data, and controlled by two terminals which called SCL(serial
clock) and SDA (serial data).At first, set up the condition of starting data transfer*1, and after that, input 8 bit data to
SDA terminal with synchronized SCL terminal clock. The order of transferring is first, MSB (the Most Scale of
Bit),and save the order. The 9th bit takes ACK (ACKnowledge) period, during SCL terminal takes “H”, this IC pull
down the SDA terminal. After transferred the necessary data, two terminals lead to set up and of data transfer stop
condition*2, thus the transfer comes to close.
As a part of transfer data write down to internal memory (V latch system), internal control
doesn’t change just after the transfer.
*1 Defined by SCL rise down SDA during ‘H’ period.
*2 Defined by SCL rise up SDA during ‘H’ period.
(2) TRANSFER DATA FORMAT
After transfer start condition, transfers slave address(1110100*) to SDA terminal, next, sub address(0000****),
control data*3, then, stop condition(See figure 1). And this LSI have a auto address increment function, then, next of
slave address transfer, transfer sub address(n)*4, group (n ) data, after that, group (n+1) and so on.
Data works with all of the bit, transfer the stop condition before stop 8bit transfer, and to stop transfer, it will be
canceled only the data of group.
*3 There are 1 to 5 groups.
*4 Pointed date by sub address becomes group No. of next control data.
Fig.1 DATA STRUCTURE “WRITE” mode
START
Condition
Slave
Address
R/W
L
*5
ACK Sub Address(n) ACK Control data(n) ACK
control data(n+1)
ACK ……
STOP condition
*5 It is called R/W bit.
data-1 means data for group-1, data-2 means data for group-2.
(3) INITIALIZE
This IC is initialized for circuit protection.
The initialization period is decided Pin 16 capacity value by internal impedance 15k, and shown with
t = -CR
×Ln(0.2). Data cannot be accepted for this period.
t = 530ms at C = 22
F, In this case, Please transmit data in consideration of the uneven after about 700ms.