Philips Semiconductors

Product data sheet

PCA9518

2004 Sep 29

3

Hub

Logic

SCL4

SCL0

SU01596

Buffer

SCL1

Buffer

SCL2

Buffer

EN1

Buffer

SCL3

Buffer

Hub

Logic

SDA4

SDA0

Buffer

SDA1

Buffer

SDA2

Buffer

Buffer

SDA3

Buffer

PCA9518

EN2

EN4

EN3

EXPSDA2

EXPSDA1

EXPSCL1

EXPSCL2

GND

Figure 2. Block Diagram: PCA9518

A more detailed view of Figure 2 buffer is shown in Figure 3.

SW00712

Data

Enable

To output

In

z

Inc

Figure 3. Buffer detail

The output pull-down voltage of each internal buffer is set for

approximately 0.5 V, while the input threshold of each internal buffer

is set about 0.07 V lower, when the output is internally driven LOW.

This prevents a lock-up condition from occurring.