Datasheet
TCA9539
SCPS202A – AUGUST 2009 – REVISED SEPTEMBER 2009 ...........................................................................................................................................
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The system master can reset the TCA9539 in the event of a time-out 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 I
2
C/SMBus
state machine. Asserting RESET causes the same reset/initialization to occur without depowering the part.
The TCA9539 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 I
2
C bus. Thus, the TCA9539 can remain a simple slave device.
The device outputs (latched) have high-current drive capability for directly driving LEDs. The device has low
current consumption.
The TCA9539 is identical to the PCA9555, except for the removal of the internal I/O pullup resistor, which greatly
reduces power consumption when the I/Os are held low, replacement of A2 with RESET, and a different address
range.
Two hardware pins (A0 and A1) are used to program and vary the fixed I
2
C address and allow up to four devices
to share the same I
2
C bus or SMBus.
ORDERING INFORMATION
T
A
PACKAGE
(1) (2)
ORDERABLE PART NUMBER TOP-SIDE MARKING
TSSOP – PW Reel of 2000 TCA9539PWR PW539
– 40 ° C to 85 ° C
QFN – RTW Reel of 3000 TCA9539RTWR PW539
(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 .
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Product Folder Link(s): TCA9539