TCA6424 Datasheet, PDF (2/29 Pages) Texas Instruments – LOW-VOLTAGE 24-BIT I2C AND SMBus I/O EXPANDER WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS

TCA6424
LOW-VOLTAGE 24-BIT I²C AND SMBus I/O EXPANDER
WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS
SCPS175 – NOVEMBER 2007
www.ti.com
DESCRIPTION/ORDERING INFORMATION (CONTINUED)
The TCA6424 consists of three 8-bit Configuration (input or output selection), Input, Output, and Polarity
Inversion (active high) registers. At power on, the I/Os are configured as inputs. However, the system master can
enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or
output is kept in the corresponding input or output register. The polarity of the Input Port register can be inverted
with the Polarity Inversion register. All registers can be read by the system master.
The system master can reset the TCA6424 in the event of a timeout or other improper operation by asserting a
low in the RESET input. The power-on reset puts the registers in their default state and initializes the I²C/SMBus
state machine. The RESET pin causes the same reset/initialization to occur without depowering the part.
The TCA6424 open-drain interrupt (INT) output is activated when any input state differs from its corresponding
Input Port register state and is used to indicate to the system master that an input state has changed.
INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the
remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via
the I²C bus. Thus, the TCA6424 can remain a simple slave device.
The device P-port outputs have high-current sink capabilities for directly driving LEDs while consuming low
device current.
One hardware pin (ADDR) can be used to program and vary the fixed I²C address and allow up to two devices to
share the same I²C bus or SMBus.
TERMINAL
PIN NO.
NAME
1
P00
2
P01
3
P02
4
P03
5
P04
6
P05
7
P06
8
P07
9
P10
10
P11
11
P12
12
P13
13
P14
14
P15
15
P16
16
P17
17
P20
18
P21
19
P22
20
P23
21
P24
22
P25
23
P26
24
P27
25
GND
26
ADDR
27
V_CCP
TERMINAL FUNCTIONS
DESCRIPTION
P-port input/output (push-pull design structure). At power on, P00 is configured as an input.
P-port input/output (push-pull design structure). At power on, P01 is configured as an input.
P-port input/output (push-pull design structure). At power on, P02 is configured as an input.
P-port input/output (push-pull design structure). At power on, P03 is configured as an input.
P-port input/output (push-pull design structure). At power on, P04 is configured as an input.
P-port input/output (push-pull design structure). At power on, P05 is configured as an input.
P-port input/output (push-pull design structure). At power on, P06 is configured as an input.
P-port input/output (push-pull design structure). At power on, P07 is configured as an input.
P-port input/output (push-pull design structure). At power on, P10 is configured as an input.
P-port input/output (push-pull design structure). At power on, P11 is configured as an input.
P-port input/output (push-pull design structure). At power on, P12 is configured as an input.
P-port input/output (push-pull design structure). At power on, P13 is configured as an input.
P-port input/output (push-pull design structure). At power on, P14 is configured as an input.
P-port input/output (push-pull design structure). At power on, P15 is configured as an input.
P-port input/output (push-pull design structure). At power on, P16 is configured as an input.
P-port input/output (push-pull design structure). At power on, P17 is configured as an input.
P-port input/output (push-pull design structure). At power on, P20 is configured as an input.
P-port input/output (push-pull design structure). At power on, P21 is configured as an input.
P-port input/output (push-pull design structure). At power on, P22 is configured as an input.
P-port input/output (push-pull design structure). At power on, P23 is configured as an input.
P-port input/output (push-pull design structure). At power on, P24 is configured as an input.
P-port input/output (push-pull design structure). At power on, P25 is configured as an input.
P-port input/output (push-pull design structure). At power on, P26 is configured as an input.
P-port input/output (push-pull design structure). At power on, P27 is configured as an input.
Ground
Address input. Connect directly to V_CCP or ground.
Supply voltage of TCA6424 for P port
2
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