PCA9545A_16 Datasheet, PDF (1/37 Pages) Texas Instruments – Interrupt Logic and Reset Functions

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PCA9545A
SCPS147D – OCTOBER 2005 – REVISED JUNE 2014
PCA9545A Low Voltage 4-channel I²C and SMbus Switch With Interrupt Logic and Reset
Functions
1 Features
•1 1-of-4 Bidirectional Translating Switches
• I²C Bus and SMBus Compatible
• Four Active-Low Interrupt Inputs
• Active-Low Interrupt Output
• Active-Low Reset Input
• Two Address Terminals, Allowing up to Four
Devices on the I²C Bus
• Channel Selection via I²C Bus, in Any
Combination
• Power-Up With All Switch Channels Deselected
• Low R_ON Switches
• Allows Voltage-Level Translation Between 1.8-V,
2.5-V, 3.3-V, and 5-V Buses
• No Glitch on Power-Up
• Supports Hot Insertion
• Low Standby Current
• Operating Power-Supply Voltage Range of
2.3 V to 5.5 V
• 5.5 V Tolerant Inputs
• 0 to 400-kHz Clock Frequency
• Latch-Up Performance Exceeds 100 mA per
JESD 78
• ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 1000-V Charged-Device Model (C101)
2 Applications
• Servers
• Routers (Telecom Switching Equipment)
• Factory Automation
• Products With I²C Slave Address Conflicts (e.g.
Multiple, Identical Temp Sensors)
3 Description
The PCA9545A is a quad bidirectional translating
switch controlled via the I²C bus. The SCL/SDA
upstream pair fans out to four downstream pairs, or
channels. Any individual SCn/SDn channel or
combination of channels can be selected, determined
by the contents of the programmable control register.
Four interrupt inputs (INT3–INT0), one for each of the
downstream pairs, are provided. One interrupt (INT)
output acts as an AND of the four interrupt inputs.
An active-low reset (RESET) input allows the
PCA9545A to recover from a situation in which one of
the downstream I²C buses is stuck in a low state.
Pulling RESET low resets the I²C state machine and
causes all the channels to be deselected, as does the
internal power-on reset function.
The pass gates of the switches are constructed such
that the VCC terminal can be used to limit the
maximum high voltage, which will be passed by the
PCA9545A. This allows the use of different bus
voltages on each pair, so that 1.8-V, 2.5-V, or 3.3-V
parts can communicate with 5-V parts, without any
additional protection. External pull-up resistors pull
the bus up to the desired voltage level for each
channel. All I/O terminals are 5.5 V tolerant.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
PCA9545A
TSSOP (20)
6.50 mm x 4.40 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
4 Simplified Application Diagram
I2C or SMBus
Master
(e.g. µProcessor)
SDA
SCL
INT
VCC
SD0
SC0
INT0
RESET
SD1
SC1
INT1
PCA9545A
A0
A1
GND
SD2
SC2
INT2
SD3
SC3
INT3
Channel 0
Channel 1
Channel 2
Channel 3
Slaves A0, A1...AN
Slaves B0, B1...BN
Slaves C0, C1...CN
Slaves D0, D1...DN
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.