PCA9674_PCA9674A_5

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 05 — 15 June 2009

6 of 32

NXP Semiconductors

PCA9674/74A

[1]

and board-level performance, the exposed pad needs to be soldered to the board using a corresponding

thermal pad on the board, and for proper heat conduction through the board thermal vias need to be

incorporated in the PCB in the thermal pad region.

7.

Functional description

Refer to Figure 1 “Block diagram of PCA9674/74A”.

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

PCA9674/74A is shown in Figure 7. Slave address pins AD2, AD1, and AD0 choose 1 of

64 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 5 “PCA9674 address map” and Table 6 “PCA9674A address map”.

Remark: When using the PCA9674A, 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 PCA9674A not to acknowledge.

be used with caution since they can interfere with:

1111 111)

Table 4.

Pin description for HVQFN16

Symbol

Pin

Description

AD2

1

address input 2

P0

2

quasi-bidirectional I/O 0

P1

3

quasi-bidirectional I/O 1

P2

4

quasi-bidirectional I/O 2

P3

5

quasi-bidirectional I/O 3

6

supply ground

P4

7

quasi-bidirectional I/O 4

P5

8

quasi-bidirectional I/O 5

P6

9

quasi-bidirectional I/O 6

P7

10

quasi-bidirectional I/O 7

INT

11

interrupt output (active LOW)

SCL

12

serial clock line

SDA

13

serial data line

14

supply voltage

AD0

15

address input 0

AD1

16

address input 1