Philips Semiconductors

Product data

PCA9501

2-kbit EEPROM and 6 address pins

2003 Sep 12

7

Quasi-bidirectional I/Os (see Figure 8)

A quasi-bidirectional I/O can be used as an input or output without the use of a control signal for data direction. At power-on the I/Os are HIGH.

These devices turn on when an output is written HIGH, and are switched off by the negative edge of SCL. The I/Os should be HIGH before

being used as inputs.

S

0

A2

A1

A0

0

A

A

A

SDA

SCL

12

34

5

6

7

8

SW00904

ACKNOWLEDGE

FROM SLAVE

R/W

START CONDITION

ACKNOWLEDGE

FROM SLAVE

SLAVE ADDRESS (I/O EXPANDER)

DATA TO PORT

DATA TO PORT

1

I/O3

0

I/O3

P

I/O3

OUTPUT

VOLTAGE

I/O3

PULL-UP

OUTPUT

CURRENT