Datasheet

TCA9509
SCPS225B –AUGUST 2011– REVISED JANUARY 2012 www.ti.com
ORDERING INFORMATION
ORDERABLE PART
T
A
PACKAGES
(1) (2)
TOP-SIDE MARKING
NUMBERS
–40°C to 85°C TCA9509RVHR RVH - QFN Tape and reel 7K
–40°C to 85°C TCA9509DGKR DGK - MSOP Tape and reel 7KQ
(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.
DESCRIPTION/ORDERING INFORMATION (CONTINUED)
The bus port B drivers are compliant with SMBus I/O levels, while the A side uses a current sensing mechanism
to detect the input or output LOW signal which prevents bus lock-up. The A side uses a 1 mA current source for
pull-up and a 200 Ω pull-down driver. This results in a LOW on the A side accommodating smaller voltage
swings. The output pull-down on the A side internal buffer LOW is set for approximately 0.2 V, while the input
threshold of the internal buffer is set about 50 mV lower than that of the output voltage LOW. When the A side
I/O is driven LOW internally, the LOW is not recognized as a LOW by the input. This prevents a lock-up condition
from occurring. The output pull-down on the B side drives a hard LOW and the input level is set at 0.3 of SMBus
or I
2
C-bus voltage level which enables B side to connect to any other I
2
C-bus devices or buffer.
The TCA9509 drivers are not enabled unless V
CCA
is above 0.8 V and V
CCB
is above 2.5 V. The enable (EN) pin
can also be used to turn the drivers on and off under system control. Caution should be observed to only change
the state of the EN pin when the bus is idle.
an
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