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APPLICATION INFORMATION

ADDR

P7

P6

P5

P3

P2

P1

P4

GND

INT

SDA

SCL

TCA6408

SDA

SCL

INT

GND

Keypad

A

B

ENABLE

Master

Controller

5

6

7

9

10

11

12

14

15

13

2

8

16

1

RESET

3

RESET

V

(1.8V)

CCI

10k

(x4)

W

P0

ALARM

Subsystem1

(e.g., Alarm)

(seenoteD)

4

100k

(x3)

W

TCA6408

WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS

SCPS151C – FEBRUARY 2007 – REVISED JUNE 2007

Figure 14 shows an application in which the TCA6408 can be used.

A.

Device address configured as 0100000 for this example.

B.

P0 and P2–P4 are configured as inputs.

C.

P1 and P5-P7 are configured as outputs.

D.

Resistors are required for inputs (on P port) that may float. If a driver to an input will never let the input float, a

resistor is not needed. Outputs (in the P port) do not need pullup resistors.

Figure 14. Typical Application

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