Philips Semiconductors

Product specification

PCA9556

Octal SMBus Registered Interface

1998 Dec 18

6

SMBus Address

00

1

1

A2

A1

A0

slave address

su01048

fixed

programmable

R/W

Figure 5. PCA9556 address

SMBus Transactions

Data is transmitted to the PCA9556 registers using Write Byte transfers (see Figures 6 and 7). Data is read from the PCA9556 registers using

Read and Receive Byte transfers (see FIgures 8 and 9).

12

SCL

WRITE TO

PORT

DATA OUT

FROM PORT

3

4

567

8

SDA

S0

A

A

A

0

0

1

1

A2

A1

A0

DATA 1

slave address

data to port

start condition

R/W

acknowledge

from slave

acknowledge

from slave

acknowledge

from slave

DATA 1 VALID

su01049

9

1

00

0

0

00

0

command byte

Figure 6. WRITE to output port register via Write Byte Protocol

12

SCL

3

4

567

8

SDA

S0

A

A

A

0

0

1

1

A2

A1

A0

DATA

slave address

data to register

start condition

R/W

acknowledge

from slave

acknowledge

from slave

acknowledge

from slave

su01050

9

00

0

0

00

1

command byte

1/0

Figure 7. WRITE to I/O configuration or polarity inversion registers via Write Byte Protocol