PCA9545A
4-CHANNEL I2C AND SMBus SWITCH
WITH INTERRUPT LOGIC AND RESET FUNCTIONS
www.ti.com
SCPS147C–OCTOBER 2005–REVISED OCTOBER 2006
FEATURES
•
•
•
•
•
•
1-of-4 Bidirectional Translating Switches
I2C Bus and SMBus Compatible
Four Active-Low Interrupt Inputs
Active-Low Interrupt Output
•
•
•
•
No Glitch on Power Up
Supports Hot Insertion
Low Standby Current
Operating Power-Supply Voltage Range of
2.3 V to 5.5 V
Active-Low Reset Input
•
•
•
5.5-V Tolerant Inputs
Two Address Pins, Allowing up to Four
Devices on the I2C Bus
Channel Selection Via I2C Bus, In Any
0 to 400-kHz Clock Frequency
•
•
Latch-Up Performance Exceeds 100 mA Per
JESD 78
Combination
Power Up With All Switch Channels
Deselected
•
ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 200-V Machine Model (A115-A)
•
•
Low RON Switches
Allows Voltage-Level Translation Between
1.8-V, 2.5-V, 3.3-V, and 5-V Buses
– 1000-V Charged-Device Model (C101)
DGV, DW, OR PW PACKAGE
(TOP VIEW)
RGW PACKAGE
(TOP VIEW)
RGY PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
A0
A1
VCC
1
20
20 19 18 17 16
SDA
SCL
INT
SC3
SD3
INT3
SC2
SD2
INT2
2
3
4
5
6
7
8
9
19
18
17
16
15
14
13
12
A1
RESET
INT0
SD0
SDA
SCL
INT
SC3
SD3
INT3
SC2
SD2
INT
15
RESET
INT0
SD0
1
2
3
4
5
RESET
INT0
SD0
SC0
INT1
SD1
SC1
GND
SC3
SD3
INT3
SC2
14
13
12
11
SC0
SC0
INT1
SD1
INT1
SC1
6
7
8 9 10
10 11
DESCRIPTION/ORDERING INFORMATION
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 pin 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
pullup resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 5.5-V tolerant.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright © 2005–2006, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.