TCA6408A Datasheet, PDF (2/35 Pages) Texas Instruments – LOW-VOLTAGE 8-BIT I2C AND SMBus I/O EXPANDER WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS

TCA6408A
SCPS192C – APRIL 2009– REVISED JULY 2009............................................................................................................................................................. www.ti.com
DESCRIPTION/ORDERING INFORMATION
This 8-bit I/O expander for the two-line bidirectional bus (I²C) is designed to provide general-purpose remote I/O
expansion for most microcontroller families via the I²C interface [serial clock (SCL) and serial data (SDA)].
The major benefit of this device is its wide V_CC range. It can operate from 1.65-V to 5.5-V on the P-port side and
on the SDA/SCL side. This allows the TCA6408A to interface with next-generation microprocessors and
microcontrollers on the SDA/SCL side, where supply levels are dropping down to conserve power. In contrast to
the dropping power supplies of microprocessors and microcontrollers, some PCB components such as LEDs
remain at a 5-V power supply.
The bidirectional voltage-level translation in the TCA6408A is provided
the V_CC of the external SCL/SDA lines. This indicates the V_CC level of
tthheroIu²CghbVus^CCt^Io.
V_CCI should be connected to
the TCA6408A. The voltage
level on the P port of the TCA6408A is determined by V_CCP.
The TCA6408A 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 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 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 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.
T_A
–40°C to 85°C
QFN – RGT
TSSOP – PW
µQFN – RSV
ORDERING INFORMATION
PACKAGE ^{(1) (2)}
ORDERABLE PART NUMBER
Reel of 3000
TCA6408ARGTR
Reel of 2000
TCA6408APWR
Reel of 3000
TCA6408ARSVR
TOP-SIDE MARKING
ZVU
PH408A
ZVU
(1) Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.
(2) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
website at www.ti.com.
2
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