PCA8575D datasheet(6/30 Pages) NXP

6 / 30 page

PCA8575_2

Product data sheet

Rev. 02 — 21 March 2007

6 of 30

NXP Semiconductors

PCA8575

Remote 16-bit I/O expander for I2C-bus with interrupt

Functional description

Refer to Figure 1 “Block diagram of PCA8575”.

7.1 Device address

Following a START condition, the bus master must send the address of the slave it is

accessing and the operation it wants to perform (read or write). The address of the

PCA8575 is shown in Figure 9. Slave address pins AD2, AD1, and AD0 choose 1 of

8 slave addresses. To conserve power, no internal pull-up resistors are incorporated on

AD2, AD1, and AD0. Address values depending on AD2, AD1, and AD0 can be found in

Table 3 “PCA8575 address map”.

Remark: The General Call address (0000 0000b) and the Device ID address

(1111 100Xb) are reserved and cannot be used as device address. Failure to follow this

requirement will cause the PCA8575 not to acknowledge.

The last bit of the ﬁrst byte deﬁnes the operation to be performed. When set to logic 1 a

read is selected, while a logic 0 selects a write operation.

When AD2, AD1 and AD0 are held to VDD or VSS, the same address as the PCF8575 is

applied.

7.1.1 Address map

Fig 9.

PCA8575 address

R/W

002aab636

programmable

slave address

Table 3.

PCA8575 address map

Address (hex)

010000020h

010000121h

010001022h

010001123h

010010024h

010010125h

010011026h

010011127h

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