TCA9538 Datasheet, PDF (23/37 Pages) Texas Instruments – Low Voltage 8-Bit I2C and SMBus Low-Power I/O Expander

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9 Application and Implementation
TCA9538
SCPS199C – AUGUST 2014 – REVISED OCTOBER 2015
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
Figure 24 shows an application in which the TCA9538 can be used.
9.2 Typical Application
V_CC
V_CC
10 kΩ⁽¹⁾ 10 kΩ⁽¹⁾ 10 kΩ 10 kΩ
SDA
Master
Controller
SCL
INT
RESET
GND
16
2 kΩ
VCC
15
SDA
14
SCL
13 _INT
3
RESET
4
P0
5
P1
P2 ⁶
7
P3
TCA9538
9
P4
10
P5
2
A1
1 _A0
P6 11
P7 12
100 kΩ
(x 3)
Subsystem 1
(e.g., temperature sensor)
INT
RESET
Subsystem 2
(e.g., counter)
A
ENABLE
B
Controlled Device
(e.g., CBT device)
GND
8
ALARM
Subsystem 3
(e.g., alarm system)
V_CC
(1) The SCL and SDA pins must be tied directly to VCC because if SCL and SDA are tied to an auxiliary power supply
that could be powered on while VCC is powered off, then the supply current, ICC, will increase as a result.
A. Device address is configured as 1110000 for this example.
B. P0, P2, and P3 are configured as outputs.
C. P1, P4, and P5 are configured as inputs.
D. P6 and P7 are not used and must be configured as outputs.
Figure 24. Application Schematic
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