PCA8534A datasheet(21/44 Pages) NXP

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PCA8534A_2

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Product data sheet

Rev. 02 — 1 June 2010

21 of 44

NXP Semiconductors

PCA8534A

Universal LCD driver for low multiplex rates

• A master receiver must signal an end of data to the transmitter by not generating an

acknowledge on the last byte that has been clocked out of the slave. In this event, the

transmitter must leave the data line HIGH to enable the master to generate a STOP

condition.

Acknowledgement on the I2C-bus is illustrated in Figure 14.

7.16.5 I2C-bus controller

The PCA8534A acts as an I2C-bus slave receiver. It does not initiate I2C-bus transfers or

transmit data to an I2C-bus master receiver. The only data output from the PCA8534A are

the acknowledge signals of the selected devices. Device selection depends on the

I2C-bus slave address, on the transferred command data and on the hardware

subaddress.

In single device applications, the hardware subaddress inputs A0, A1, and A2 are

normally tied to VSS which defines the hardware subaddress 0. In multiple device

applications A0, A1, and A2 are tied to VSS or VDD using a binary coding scheme, so that

no two devices with a common I2C-bus slave address have the same hardware

subaddress.

7.16.6 Input filters

To enhance noise immunity in electrically adverse environments, RC low-pass filters are

provided on the SDA and SCL lines.

7.16.7 I2C-bus protocol

Two I2C-bus slave addresses (0111 000 and 0111 001) are used to address the

PCA8534A. The entire I2C-bus slave address byte is shown in Table 8.

Fig 14. Acknowledgement of the I2C-bus

mbc602

START

condition

clock pulse for

acknowledgement

not acknowledge

acknowledge

data output

by transmitter

data output

by receiver

SCL from

master

Table 8.

I2C slave address byte

Slave address

Bit

MSB

LSB

SA0

R/W

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