TCA6408A-Q1 Datasheet, PDF (15/40 Pages) Texas Instruments – Low-Voltage 8-Bit I2C and SMBus I/O Expander With Interrupt Output

www.ti.com
8 Detailed Description
TCA6408A-Q1
SCPS234 – SEPTEMBER 2016
8.1 Overview
The bidirectional voltage-level translation in the TCA6408A-Q1 is provided through V_CCI. V_CCI must be connected
to the V_CC of the external SCL/SDA lines. This indicates the V_CC level of the I²C bus to the TCA6408A-Q1. The
voltage level on the P-port of the TCA6408A-Q1 is determined by V_CCP.
The TCA6408A-Q1 consists of one 8-bit Configuration (input or output selection), Input, Output, and Polarity
Inversion (active high) Register. 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 TCA6408A-Q1 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 TCA6408A-Q1 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 TCA6408A-Q1 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.
Copyright © 2016, Texas Instruments Incorporated
Product Folder Links: TCA6408A-Q1
Submit Documentation Feedback
15