A

A

S

0

1

0

0

A1

A2

A0

0

Start

Condition

ACK

From Slave

ACK

From Slave

Data

Data

Slave Address

R/W

P7

P6

1

P0

P7

P0

A

Integral Multiples of Two Bytes

P5

SCL

SDA

Write to

Port

Data Output

Voltage

P5 Output

Voltage

P5 Pullup

Output

Current

INT

ACK

From Slave

Data A0

and B0

Valid

1

2

3

4

5

6

7

8

1

2

3

4

5

6

7

8

1

2

3

4

5

6

7

8

PCF8574

www.ti.com

SCPS068I – JULY 2001 – REVISED NOVEMBER 2015

8.3.3 Address Reference

INPUTS

8-BIT WRITE

READ ADDRESS

A2

A1

A0

ADDRESS

65 (decimal), 41

64 (decimal), 40

L

L

L

(hexadecimal)

(hexadecimal)

67 (decimal), 43

66 (decimal), 42

L

L

H

(hexadecimal)

(hexadecimal)

69 (decimal), 45

68 (decimal), 44

L

H

L

(hexadecimal)

(hexadecimal)

71 (decimal), 47

70 (decimal), 46

L

H

H

(hexadecimal)

(hexadecimal)

73 (decimal), 49

72 (decimal), 48

H

L

L

(hexadecimal)

(hexadecimal)

75 (decimal), 4B

74 (decimal), 4A

H

L

H

(hexadecimal)

(hexadecimal)

77 (decimal), 4D

76 (decimal), 4C

H

H

L

(hexadecimal)

(hexadecimal)

79 (decimal), 4F

78 (decimal), 4E

H

H

H

(hexadecimal)

(hexadecimal)

8.4 Device Functional Modes

Figure 16 and Figure 17 show the address and timing diagrams for the write and read modes, respectively.

Figure 16. Write Mode (Output)

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