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TCA9544A
SCPS209C – MAY 2014 – REVISED NOVEMBER 2019
TCA9544A Low Voltage 4-Channel I2C and SMBus Multiplexer With Interrupt Logic
1 Features
2 Applications
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1-of-4 Bidirectional Translating Switches
I2C Bus and SMBus Compatible
Four Active-Low Interrupt Inputs
Active-Low Interrupt Output
Three Address Pins, Allowing up to Eight
TCA9544A Devices on the I2C Bus
Channel Selection Via I2C Bus
Power-Up With All Switch Channels Deselected
Low RON 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
1.65 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
– 4000-V Human-Body Model (A114-A)
– 1500-V Charged-Device Model (C101)
Servers
Routers (Telecom Switching Equipment)
Factory Automation
Products With I2C Slave Address Conflicts (For
Example, Multiple, Identical Temp Sensors)
3 Description
The TCA9544A is a 4-channel, bidirectional
translating I2C Muliplexer. The master SCL/SDA
signal pair is directed to one of the four channels of
slave devices, SC0/SD0-SC3/SD3. Four interrupt
inputs (INT3–INT0), one for each of the downstream
pairs, are provided. One interrupt output (INT) acts as
an AND of the four interrupt inputs.
A power-on reset function returns the registers to
their default state and initializes the I2C state
machine, with all channels deselected.
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 TCA9544A.
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
pins are 5.5 V tolerant.
Device Information(1)
PART NUMBER
TCA9544A
PACKAGE
TSSOP (20)
BODY SIZE (NOM)
6.50 mm × 4.40 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
I2C or SMBus
Master
SDA
SCL
INT
VCC
Channel 0
SD0
SC0
INT0
SD1
SC1
INT1
(e.g. Processor)
TCA9544A
A0
A1
A2
GND
SD2
SC2
INT1
SD3
SC3
INT3
Slaves A0, A1...AN
Channel 1
Slaves B0, B1...BN
Channel 2
Slaves C0, C1...CN
Channel 3
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.
TCA9544A
SCPS209C – MAY 2014 – REVISED NOVEMBER 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
4
4
4
4
5
6
6
7
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions ......................
Thermal Information ..................................................
Electrical Characteristics...........................................
I2C Interface Timing Requirements...........................
Switching Characteristics ..........................................
Interrupt Timing Requirements .................................
Typical Characteristics ..............................................
Parameter Measurement Information .................. 8
Detailed Description ............................................ 10
8.1 Overview ................................................................. 10
8.2 Functional Block Diagram ....................................... 10
8.3
8.4
8.5
8.6
9
Feature Description.................................................
Device Functional Modes........................................
Programming ..........................................................
Control Register ......................................................
11
11
11
13
Application and Implementation ........................ 16
9.1 Application Information............................................ 16
9.2 Typical Application .................................................. 16
10 Power Supply Recommendations ..................... 19
10.1 Power-On Reset Requirements ........................... 19
11 Layout................................................................... 21
11.1 Layout Guidelines ................................................. 21
11.2 Layout Example .................................................... 21
12 Device and Documentation Support ................. 22
12.1
12.2
12.3
12.4
12.5
Receiving Notification of Documentation Updates
Support Resources ...............................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
22
13 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
Changes from Revision B (May 2018) to Revision C
•
Page
Changed VCC = 1.65 V to 5.5 V To: VCC = 2.5 V in Figure 15 ............................................................................................. 16
Changes from Revision A (May 2014) to Revision B
Page
•
Changed the first paragraph of the Description...................................................................................................................... 1
•
Added Tstg to the Absolute Maximum Ratings table............................................................................................................... 4
•
Changed the first paragraph of the Overview section .......................................................................................................... 10
•
Changed "switch" to "multiplexer" in the Feature Description section.................................................................................. 11
•
Changed text in the Control Register Definition section From: "One or several SCn/SDn downstream pairs, or
channels, are selected..." To: "One SCn/SDn downstream pair, or channel, is selected..."................................................ 14
Changes from Original (May 2014) to Revision A
•
2
Page
Updated document from PREVIEW to PRODUCTION DATA. ............................................................................................. 1
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SCPS209C – MAY 2014 – REVISED NOVEMBER 2019
5 Pin Configuration and Functions
PW Package
Top View
A0
1
20
VCC
A1
2
19
SDA
A2
3
18
SCL
INT0
4
17
INT
SD0
5
16
SC3
SC0
6
15
SD3
INT1
7
14
INT3
SD1
8
13
SC2
SC1
9
12
SD2
GND
10
11
INT2
Not to scale
Pin Functions
PIN
NAME
DESCRIPTION
NO.
A0
1
Address input 0. Connect directly to VCC or ground.
A1
2
Address input 1. Connect directly to VCC or ground.
A2
3
Address input 2. Connect directly to VCC or ground.
INT0
4
Active-low interrupt input 0. Connect to VDPU0 (1) through a pull-up resistor.
SD0
5
Serial data 0. Connect to VDPU0 (1) through a pull-up resistor.
SC0
6
Serial clock 0. Connect to VDPU0 (1) through a pull-up resistor.
INT1
7
Active-low interrupt input 1. Connect to VDPU1 (1) through a pull-up resistor.
SD1
8
Serial data 1. Connect to VDPU1 (1) through a pull-up resistor.
SC1
9
Serial clock 1. Connect to VDPU1 (1) through a pull-up resistor.
GND
10
Ground
INT2
11
Active-low interrupt input 2. Connect to VDPU2 (1) through a pull-up resistor.
SD2
12
Serial data 2. Connect to VDPU2 (1) through a pull-up resistor.
SC2
13
Serial clock 2. Connect to VDPU2 (1) through a pull-up resistor.
INT3
14
Active-low interrupt input 3. Connect to VDPU3 (1) through a pull-up resistor.
SD3
15
Serial data 3. Connect to VDPU3 (1) through a pull-up resistor.
SC3
16
Serial clock 3. Connect to VDPU3 (1) through a pull-up resistor.
INT
17
Active-low interrupt output. Connect to VDPUM (1) through a pull-up resistor.
SCL
18
Serial clock line. Connect to VDPUM (1) through a pull-up resistor.
SDA
19
Serial data line. Connect to VDPUM (1) through a pull-up resistor.
VCC
20
Supply power
(1)
VDPUX is the pull-up reference voltage for the associated data line. VDPUM is the master I2C reference voltage while VDPU0 — VDPU3 are
the slave channel reference voltages.
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6 Specifications
6.1 Absolute Maximum Ratings (1)
over operating free-air temperature (unless otherwise noted)
VCC
MIN
MAX
Supply voltage
–0.5
7
(2)
–0.5
UNIT
V
VI
Input voltage
II
Input current
±20
7
mA
V
IO
Output current
±25
mA
Continuous current through VCC
±100
mA
Continuous current through GND
±100
mA
400
mW
Ptot
Total power dissipation
TA
Operating free-air temperature range
–40
85
°C
Tstg
Storage temperature range
–65
150
°C
(1)
(2)
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating
conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
The input negative-voltage and output voltage ratings may be exceeded if the input and output current ratings are observed.
6.2 ESD Ratings
V(ESD)
(1)
(2)
Electrostatic discharge
MIN
MAX
UNIT
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1)
–4000
4000
V
Charged device model (CDM), per JEDEC specification JESD22-C101,
all pins (2)
–1500
1500
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions (1)
VCC
Supply voltage
VIH
High-level input voltage
VIL
Low-level input voltage
TA
Operating free-air temperature
(1)
MIN
MAX
1.65
5.5
SCL, SDA
0.7 × VCC
6
A2–A0, INT3–INT0
0.7 × VCC
VCC + 0.5
SCL, SDA
–0.5
0.3 × VCC
A2–A0, INT3–INT0
–0.5
0.3 × VCC
–40
85
UNIT
V
V
V
°C
All unused inputs of the device must be held at VCC or GND to ensure proper device operation. Refer to the TI application report,
Implications of Slow or Floating CMOS Inputs, literature number SCBA004.
6.4 Thermal Information (1)
over operating free-air temperature range (unless otherwise noted)
TCA9544A
THERMAL METRIC (1)
PW
UNIT
20 PIN
RθJA
Junction-to-ambient thermal resistance
118.2
°C/W
RθJCtop
Junction-to-case (top) thermal resistance
51.4
°C/W
RθJB
Junction-to-board thermal resistance
69.3
°C/W
ψJT
Junction-to-top characterization parameter
7.7
°C/W
ψJB
Junction-to-board characterization parameter
68.8
v
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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6.5 Electrical Characteristics (1)
over recommended operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
VPORR
Power-on reset voltage, VCC
rising
No load:
VI = VCC or GND
VPORF
Power-on reset voltage, VCC
falling (3)
No load:
VI = VCC or GND
VCC
MIN TYP (2)
MAX
1.2
1.5
0.8
5V
2.6
3.3 V
Switch output voltage
VSWin = VCC
ISWout = –100 μA
3 to 3.6 V
1.65 to 1.95 V
VO = VCC
VOL = 0.6 V
INT
2.8
1.4
1.0
1.65 to 5.5 V
VOL = 0.4 V
1.8
0.5
1.1
10
3
7
6
10
A2–A0
VI = VCC or GND
±1
1.65 to 5.5 V
±1
INT3–INT0
VI = VCC or GND
IO = 0
tr,max = 300 ns
Operating
mode
fSCL = 100 kHz
VI = VCC or GND
IO = 0
tr,max = 1 µs
ICC
Low inputs
VI = GND
IO = 0
Standby mode
High inputs
INT3–INT0
Supply-current
change
SCL, SDA
(1)
(2)
(3)
A2–A0
INT3–INT0
μA
±1
fSCL = 400 kHz
Ci
mA
±1
SC3–SC0, SD3–SD0
ΔICC
μA
3
SCL, SDA
II
V
0.8
1.65 to 5.5 V
VOL = 0.4 V
SDA
IOL
4.5
1.6
1.8 V
INT
V
1.9
2.5 V
2.3 to 2.7 V
IOH
V
3.6
4.5 to 5.5 V
Vpass
1
UNIT
VI = VCC
IO = 0
5.5 V
50
3.6 V
20
2.7 V
11
1.65 V
6
5.5 V
35
3.6 V
14
2.7 V
5
1.65 V
2
5.5 V
1.6
2
3.6 V
1.0
1.3
2.7 V
0.7
1.1
1.65 V
0.4
0.55
5.5 V
1.6
2
3.6 V
1.0
1.3
2.7 V
0.7
1.1
1.65 V
0.4
0.55
3
20
3
20
2
15
2
15
4.5
6
4.5
6
One INT3–INT0 input at 0.6 V,
Other inputs at VCC or GND
One INT3–INT0 input at VCC – 0.6 V,
Other inputs at VCC or GND
SCL or SDA input at 0.6 V,
Other inputs at VCC or GND
1.65 to 5.5 V
SCL or SDA inputs at VCC – 0.6 V,
Other inputs at VCC or GND
VI = VCC or GND
1.65 to 5.5 V
μA
μA
pF
For operation between specified voltage ranges, refer to the worst-case parameter in both applicable ranges.
All typical values are at nominal supply voltage (1.8-V, 2.5-V, 3.3-V, or 5-V VCC), TA = 25°C.
The power-on reset circuit resets the I2C bus logic when VCC < VPORF.
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Electrical Characteristics(1) (continued)
over recommended operating free-air temperature range (unless otherwise noted)
PARAMETER
(4)
Cio(OFF)
SCL, SDA
SC3–SC0, SD3–SD0
RON
VI = VCC or GND
Switch OFF
VO = 0.4 V
IO = 15 mA
MAX
15
19
6
8
4.5 to 5.5 V
10
16
VCC
1.65 to 5.5 V
3 to 3.6 V
13
20
2.3 to 2.7 V
16
45
1.65 to 1.95 V
25
70
Switch-on resistance
VO = 0.4 V
(4)
MIN TYP (2)
TEST CONDITIONS
IO = 10 mA
UNIT
pF
Ω
Cio(ON) depends on device capacitance and load that is downstream from the device.
6.6 I2C Interface Timing Requirements
over recommended operating free-air temperature range (unless otherwise noted)
STANDARD-MODE
I2C BUS
MIN
MAX
100
FAST-MODE
I2C BUS
UNIT
MIN
MAX
0
400
fscl
I2C clock frequency
0
tsch
I2C clock high time
4
0.6
μs
tscl
I2C clock low time
4.7
1.3
μs
2
50
tsp
I C spike time
tsds
I2C serial-data setup time
250
100
ns
tsdh
I2C serial-data hold time
0 (1)
0 (1)
μs
2
50
kHz
ns
ticr
I C input rise time
1000 20 + 0.1Cb
(2)
300
ns
ticf
I2C input fall time
300 20 + 0.1Cb
(2)
300
ns
tocf
I2C output fall time (10-pF to 400-pF bus)
300 20 + 0.1Cb
(2)
300
ns
tbuf
I2C bus free time between stop and start
2
4.7
1.3
μs
tsts
I C start or repeated start condition setup
4.7
0.6
μs
tsth
I2C start or repeated start condition hold
4
0.6
μs
tsps
I2C stop condition setup
4
0.6
μs
(3)
tvdL(Data)
Valid-data time (high to low)
tvdH(Data)
Valid-data time (low to high) (3)
SCL low to SDA output high valid
tvd(ack)
Valid-data time of ACK condition
ACK signal from SCL low
to SDA output low
Cb
I2C bus capacitive load
(1)
(2)
(3)
SCL low to SDA output low valid
1
1
μs
0.6
0.6
μs
1
1
μs
400
400
pF
A device internally must provide a hold time of at least 300 ns for the SDA signal (referred to as the VIH min of the SCL signal), in order
to bridge the undefined region of the falling edge of SCL.
Cb = total bus capacitance of one bus line in pF
Data taken using a 1-kΩ pullup resistor and 50-pF load (see Figure 5).
6.7 Switching Characteristics
over recommended operating free-air temperature range, CL ≤ 100 pF (unless otherwise noted) (see Figure 5)
PARAMETER
tpd
(1)
Propagation delay time
RON = 20 Ω, CL = 15 pF
RON = 20 Ω, CL = 50 pF
FROM
(INPUT)
TO
(OUTPUT)
SDA or SCL
SDn or SCn
MIN
MAX
0.3
1
UNIT
ns
tiv
Interrupt valid time (2)
INTn
INT
4
μs
tir
Interrupt reset delay time (2)
INTn
INT
2
μs
(1)
(2)
6
The propagation delay is the calculated RC time constant of the typical ON-state resistance of the switch and the specified load
capacitance, when driven by an ideal voltage source (zero output impedance).
Data taken using a 4.7-kΩ pullup resistor and 100-pF load (see Figure 6).
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6.8 Interrupt Timing Requirements
over recommended operating free-air temperature range (unless otherwise noted)
PARAMETER
MIN
MAX
UNIT
tPWRL
Low-level pulse duration rejection of INTn inputs
(1)
1
μs
tPWRH
High-level pulse duration rejection of INTn inputs (1)
0.5
μs
(1)
Data taken using a 4.7-kΩ pullup resistor and 100-pF load (see Figure 6).
6.9 Typical Characteristics
800
1.8
VCC = 5.5V
VCC = 3.3V
VCC = 1.65V
1.6
ICC, Standby Mode (µA)
700
VOL (mV)
600
500
400
300
200
1.2
1
0.8
0.6
25ºC (Room Temperature)
85ºC
-40ºC
0.4
100
0.2
1.5
0
0
2
4
IOL
6
(mA)
8
10
12
2
2.5
3
D003
Figure 1. SDA Output Low Voltage (VOL) vs Load Current
(IOL) at Three VCC Levels
3.5
VCC (V)
4
4.5
5
5.5
D004
Figure 2. Standby Current (ICC) vs Supply Voltage (VCC) at
Three Temperature Points
30
6
25ºC (Room Temperature)
85ºC
-40º
5.8
5.6
25
5.4
20
RON (Ohm)
CIO(OFF) (pF)
1.4
5.2
5
4.8
15
10
4.6
4.4
25ºC (Room Temperature)
85ºC
-40ºC
5
4.2
0
4
0
0.5
1
1.5
2
2.5
3
VCC (V)
3.5
4
4.5
5
5.5
0
0.5
D006
Figure 3. Slave channel (SCn/SDn) capacitance (Cio(OFF)) vs.
Supply Voltage (VCC) at Three Temperature Points
1
1.5
2
2.5
3
VCC (V)
3.5
4
4.5
5
5.5
D001
Figure 4. ON-Resistance (RON) vs Supply Voltage (VCC) at
Three Temperatures
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7 Parameter Measurement Information
VCC
RL = 1 kΩ
SDn, SCn
DUT
CL = 50 pF
(See Note A)
I2C-PORT LOAD CONFIGURATION
Two Bytes for Complete
Device Programming
Address
Stop
Start
Address
Bit 7
Condition Condition
Bit 6
(MSB)
(P)
(S)
BYTE
DESCRIPTION
1
I2C address + R/W
2
Control register data
Address
Bit 1
tscl
R/W
Bit 0
(LSB)
ACK
(A)
Data
Bit 7
(MSB)
Data
Bit 0
(LSB)
ACK
(A)
Stop
Condition
(P)
tsch
0.7 × VCC
SCL
ticr
ticf
tbuf
tsp
tvd(ACK)
or tvdL
tvdH
0.3 × VCC
tsts
0.7 × VCC
SDA
0.3 × VCC
ticf
ticr
tsth
tsdh
tsds
tsps
Repeat
Start
Condition
Start or Repeat
Start Condition
Stop
Condition
VOLTAGE WAVEFORMS
NOTES: A. CL includes probe and jig capacitance.
B. All input pulses are supplied by generators having the following characteristics: PRR ≤ 10 MHz, ZO = 50 Ω, tr/tf ≤ 30 ns.
C. The outputs are measured one at a time, with one transition per measurement.
Figure 5. I2C Interface Load Circuit, Byte Descriptions, and Voltage Waveforms
8
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Parameter Measurement Information (continued)
VCC
RL = 4.7 kΩ
DUT
INT
CL = 100 pF
(See Note A)
INTERRUPT LOAD CONFIGURATION
INTn
(input)
0.5 × VCC
INTn
(input)
tir
tiv
INT
(output)
0.5 × VCC
0.5 × VCC
INT
(output)
VOLTAGE WAVEFORMS (tiv)
0.5 × VCC
VOLTAGE WAVEFORMS (tir)
NOTES: A. CL includes probe and jig capacitance.
B. All input pulses are supplied by generators having the following characteristics: PRR ≤ 10 MHz, ZO = 50 Ω, tr/tf ≤ 30 ns.
Figure 6. Interrupt Load Circuit and Voltage Waveforms
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8 Detailed Description
8.1 Overview
The TCA9544A is a 4-channel, bidirectional translating I2C Muliplexer. The master SCL/SDA signal pair is
directed to one of the four channels of slave devices, SC0/SD0-SC3/SD3. Four interrupt inputs (INT3–INT0), one
for each of the downstream pairs, are provided. One interrupt output (INT) acts as an AND of the four interrupt
inputs.
The device can be reset by cycling the power supply, VCC, also known as a power-on reset (POR), which resets
the state machine and allows the TCA9544A to recover should one of the downstream I2C buses get stuck in a
low state. A POR event will cause all channels to be deselected.
The connections of the I2C data path are controlled by the same I2C master device that is switched to
communicate with multiple I2C slaves. After the successful acknowledgment of the slave address (hardware
selectable by A0-A2 pins), a single 8-bit control register is written to or read from to determine the selected
channels and state of the interrupts.
The TCA9544A may also be used for voltage translation, allowing the use of different bus voltages on each
SCn/SDn pair such that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts. This is achieved by using
external pull-up resistors to pull the bus up to the desired voltage for the master and each slave channel.
8.2 Functional Block Diagram
TCA9544A
SC0
SC1
SC2
SC3
SD0
SD1
6
9
13
16
5
8
12
SD2
SD3
GND
VCC
SCL
SDA
INT0
INT1
INT2
INT3
10
15
Switch Control Logic
10
20
Power-on Reset
18
19
1
Input Filter
4
7
11
14
2
I2C Bus Control
Interrupt Logic
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Output
Filter
17
A0
A1
A2
INT
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8.3 Feature Description
The TCA9544A is a 4-channel, bidirectional translating multiplexer for I2C buses that supports Standard-Mode
(100 kHz) and Fast-Mode (400 kHz) operation. The TCA9544A features I2C control using a single 8-bit control
register in which the three least significant bits control the enabling and disabling of the 4 switch channels of I2C
data flow. The TCA9544A also supports interrupt signals for each slave channel and this data is held in the four
most significant bits of the control register. Depending on the application, voltage translation of the I2C bus can
also be achieved using the TCA9544A to allow 1.8-V, 2.5-V, or 3.3-V parts to communicate with 5-V parts.
Additionally, in the event that communication on the I2C bus enters a fault state, the TCA9544A can be reset to
resume normal operation by means of a power-on reset which results from cycling power to the device.
8.4 Device Functional Modes
8.4.1 Power-On Reset
When power is applied to VCC, an internal power-on reset holds the TCA9544A in a reset condition until VCC has
reached VPORR. At this point, the reset condition is released, and the TCA9544A registers and I2C state machine
are initialized to their default states, all zeroes, causing all the channels to be deselected. Thereafter, VCC must
be lowered below VPORF to reset the device.
8.5 Programming
8.5.1 I2C Interface
The I2C bus is for two-way two-line communication between different ICs or modules. The two lines are a serial
data line (SDA) and a serial clock line (SCL). Both lines must be connected to a positive supply via a pull-up
resistor when connected to the output stages of a device. Data transfer can be initiated only when the bus is not
busy.
One data bit is transferred during each clock pulse. The data on the SDA line must remain stable during the high
period of the clock pulse, as changes in the data line at this time are interpreted as control signals (see Figure 7).
SDA
SCL
Data Line
Stable;
Data Valid
Change
of Data
Allowed
Figure 7. Bit Transfer
Both data and clock lines remain high when the bus is not busy. A high-to-low transition of the data line while the
clock is high is defined as the start condition (S). A low-to-high transition of the data line while the clock is high is
defined as the stop condition (P) (see Figure 8).
SDA
SCL
S
P
Start Condition
Stop Condition
Figure 8. Definition of Start and Stop Conditions
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Programming (continued)
A device generating a message is a transmitter; a device receiving a message is the receiver. The device that
controls the message is the master, and the devices that are controlled by the master are the slaves (see
Figure 9).
SDA
SCL
Master
Transmitter/
Receiver
Slave
Transmitter/
Receiver
Slave
Receiver
I2C
Multiplexer
Master
Transmitter/
Receiver
Master
Transmitter
Slave
Figure 9. System Configuration
The number of data bytes transferred between the start and the stop conditions from transmitter to receiver is not
limited. Each byte of eight bits is followed by one ACK bit. The transmitter must release the SDA line before the
receiver can send an ACK bit.
When a slave receiver is addressed, it must generate an acknowledge (ACK) after the reception of each byte.
Also, a master must generate an ACK after the reception of each byte that has been clocked out of the slave
transmitter. The device that acknowledges must pull down the SDA line during the ACK clock pulse so that the
SDA line is stable low during the high pulse of the ACK-related clock period (see Figure 10). Setup and hold
times must be taken into account.
Data Output
by Transmitter
NACK
Data Output
by Receiver
ACK
SCL From
Master
1
2
8
9
S
Clock Pulse for ACK
Start
Condition
Figure 10. Acknowledgment on the I2C Bus
A master receiver must signal an end of data to the transmitter by not generating an acknowledge (NACK) after
the last byte has been clocked out of the slave. This is done by the master receiver by holding the SDA line high.
In this event, the transmitter must release the data line to enable the master to generate a stop condition.
Data is transmitted to the TCA9544A control register using the write mode shown in Figure 11.
12
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Programming (continued)
Slave Address
SDA
S
1
1
1
0
Control Register
A2 A1 A0
Start Condition
0
A
X
X
X
X
X
B2 B1 B0
R/W ACK From Slave
A
ACK From Slave
P
Stop Condition
Figure 11. Write Control Register
Data is read from the TCA9544A control register using the read mode shown in Figure 12.
Slave Address
SDA
S
1
1
1
0
A2
Control Register
A1
Start Condition
A0
1
A
R/W
INT3 INT2 INT1 INT0
B2
0
ACK From Slave
B1
B0
NA
NACK From Master
P
Stop Condition
Figure 12. Read Control Register
8.6 Control Register
8.6.1 Device Address
Following a start condition, the bus master must output the address of the slave it is accessing. The address of
the TCA9544A is shown in Figure 13. To conserve power, no internal pullup resistors are incorporated on the
hardware-selectable address pins, and they must be pulled high or low.
Slave Address
1
1
1
Fixed
0
A2
A1
A0 R/W
Hardware
Selectable
Figure 13. TCA9544A Address
The last bit of the slave address defines the operation to be performed. When set to a logic 1, a read is selected,
while a logic 0 selects a write operation.
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Control Register (continued)
8.6.2 Control Register Description
Following the successful acknowledgment of the slave address, the bus master sends a byte to the TCA9544A,
which is stored in the control register. If multiple bytes are received by the TCA9544A, it saves the last byte
received. This register can be written and read via the I2C bus.
Channel-Selection Bits
(Read/Write)
Interrupt Bits
(Read Only)
7
6
5
4
INT3 INT2 INT1 INT0
3
2
1
0
X
B2
B1
B0
Enable Bit
INT0
INT1
INT2
INT3
Figure 14. Control Register
8.6.3 Control Register Definition
Only one SCn/SDn downstream pair, or channel, can be selected by the contents of the control register (see
Table 1). This register is written after the TCA9544A has been addressed. The three LSBs of the control byte are
used to determine which channel (or channels) is to be selected. When a channel is selected, the channel
becomes active after a stop condition has been placed on the I2C bus. This ensures that all SCn/SDn lines are in
a high state when the channel is made active, so that no false conditions are generated at the time of
connection. A stop condition always must occur right after the acknowledge cycle.
Table 1. Control Register Write (Channel Selection), Control Register Read (Channel Status) (1)
(1)
14
INT3
INT2
INT1
INT0
D3
B2
B1
B0
X
X
X
X
X
0
X
X
No channel selected
COMMAND
X
X
X
X
X
1
0
0
Channel 0 enabled
X
X
X
X
X
1
0
1
Channel 1 enabled
X
X
X
X
X
1
1
0
Channel 2 enabled
X
X
X
X
X
1
1
1
Channel 3 enabled
0
0
0
0
0
0
0
0
No channel selected,
power-up default state
Only one channel may be selected at a time.
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8.6.4 Interrupt Handling
The TCA9544A provides four interrupt inputs (one for each channel) and one open-drain interrupt output. When
an interrupt is generated by any device, it is detected by the TCA9544A, and the interrupt output is driven low.
The channel does not need to be active for detection of the interrupt. A bit also is set in the control register (see
Table 2).
Bits 4–7 of the control register correspond to channels 0–3 of the TCA9544A, respectively. Therefore, if an
interrupt is generated by any device connected to channel 1, the state of the interrupt inputs is loaded into the
control register when a read is accomplished. Likewise, an interrupt on any device connected to channel 0
causes bit 4 of the control register to be set on the read. The master then can address the TCA9544A and read
the contents of the control register to determine which channel contains the device generating the interrupt. The
master can reconfigure the TCA9544A to select this channel and locate the device generating the interrupt and
clear it. Once the device responsible for the interrupt clears, the interrupt clears.
It should be noted that more than one device can provide an interrupt on a channel, so it is up to the master to
ensure that all devices on a channel are interrogated for an interrupt.
The interrupt inputs can be used as general-purpose inputs if the interrupt function is not required.
If unused, interrupt input(s) must be connected to VCC.
Table 2. Control Register Read (Interrupt) (1)
INT3
X
X
X
0
1
(1)
INT2
X
X
0
1
X
INT1
X
INT0
0
D3
B2
B1
B0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0
1
1
COMMAND
No interrupt on channel 0
Interrupt on channel 0
No interrupt on channel 1
Interrupt on channel 1
No interrupt on channel 2
Interrupt on channel 2
No interrupt on channel 3
Interrupt on channel 3
Several interrupts can be active at the same time. For example, INT3 = 0, INT2 = 1, INT1 = 1, INT0 = 0 means that there is no interrupt
on channels 0 and 3, and there is interrupt on channels 1 and 2.
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
Applications of the TCA9544A will contain an I2C (or SMBus) master device and up to four I2C slave devices.
The downstream channels are ideally used to resolve I2C slave address conflicts. For example, if four identical
digital temperature sensors are needed in the application, one sensor can be connected at each channel: 0, 1, 2,
and 3. When the temperature at a specific location needs to be read, the appropriate channel can be enabled
and all other channels switched off, the data can be retrieved, and the I2C master can move on and read the next
channel.
In an application where the I2C bus will contain many additional slave devices that do not result in I2C slave
address conflicts, these slave devices can be connected to any desired channel to distribute the total bus
capacitance across multiple channels. If multiple switches will be enabled simultaneously, additional design
requirements must be considered (See Design Requirements and Detailed Design Procedure).
9.2 Typical Application
A typical application of the TCA9544A contains anywhere from 1 to 5 separate data pull-up voltages, VDPUX , one
for the master device (VDPUM) and one for each of the selectable slave channels (VDPU0 – VDPU3). In the event
where the master device and all slave devices operate at the same voltage, then the supply voltage can be VCC
= VDPUX. In an application where voltage translation is necessary, additional design requirements must be
considered (See Design Requirements).
Figure 15 shows an application in which the TCA9544A can be used.
VDPUM = 1.65 V to 5.5 V
VCC = 2.5 V
VDPU0 = 1.65 V to 5.5 V
20
SDA
I2C/SMBus
Master
SCL
VCC
19
SD0
5
SC0
6
4
SDA
18
17
SCL
INT
INT0
Channel 0
VDPU1 = 1.65 V to 5.5 V
SD1
SC1
INT1
8
Channel 1
9
7
VDPU2 = 1.65 V to 5.5 V
TCA9544A
SD2
SC2
12
Channel 2
13
11
INT2
3
A2
2
A1
1
A0
10
GND
SD3
SC3
INT3
VDPU3 = 1.65 V to 5.5 V
15
Channel 3
16
14
Figure 15. Typical Application Schematic
16
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Typical Application (continued)
9.2.1 Design Requirements
The pull-up resistors on the INT3-INT0 pins in the application schematic are not required in all applications. If the
device generating the interrupt has an open-drain output structure or can be tri-stated, a pull-up resistor is
required. If the device generating the interrupt has a push-pull output structure and cannot be tri-stated, a pull-up
resistor is not required. The interrupt inputs should not be left floating in the application.
The A0 and A1 pins are hardware selectable to control the slave address of the TCA9544A. These pins may be
tied directly to GND or VCC in the application.
If multiple slave channels will be activated simultaneously in the application, then the total IOL from SCL/SDA to
GND on the master side will be the sum of the currents through all pull-up resistors, Rp.
The pass-gate transistors of the TCA9544A are constructed such that the VCC voltage can be used to limit the
maximum voltage that is passed from one I2C bus to another.
Figure 16 shows the voltage characteristics of the pass-gate transistors (note that the graph was generated using
data specified in the Electrical Characteristics section of this data sheet). In order for the TCA9544A to act as a
voltage translator, the Vpass voltage must be equal to or lower than the lowest bus voltage. For example, if the
main bus is running at 5 V and the downstream buses are 3.3 V and 2.7 V, Vpass must be equal to or below 2.7 V
to effectively clamp the downstream bus voltages. As shown in Figure 16, Vpass(max) is 2.7 V when the TCA9544A
supply voltage is 4 V or lower, so the TCA9544A supply voltage could be set to 3.3 V. Pull-up resistors then can
be used to bring the bus voltages to their appropriate levels (see Figure 15).
9.2.2 Detailed Design Procedure
Once all the slaves are assigned to the appropriate slave channels and bus voltages are identified, the pull-up
resistors, Rp, for each of the buses need to be selected appropriately. The minimum pull-up resistance is a
function of VDPUX, VOL,(max), and IOL:
VDPUX - VOL(max)
Rp(min) =
IOL
(1)
The maximum pull-up resistance is a function of the maximum rise time, tr (300 ns for fast-mode operation, fSCL =
400 kHz) and bus capacitance, Cb:
tr
Rp(max) =
0.8473 ´ Cb
(2)
The maximum bus capacitance for an I2C bus must not exceed 400 pF for fast-mode operation. The bus
capacitance can be approximated by adding the capacitance of the TCA9544A, Cio(OFF), the capacitance of
wires/connections/traces, and the capacitance of each individual slave on a given channel. If multiple channels
will be activated simultaneously, each of the slaves on all channels will contribute to total bus capacitance.
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Typical Application (continued)
9.2.3 TCA9544A Application Curves
25
5
20
Rp(max) (kOhm)
4
Vpass (V)
Standard-mode
Fast-mode
25ºC (Room Temperature)
85ºC
-40ºC
3
2
15
10
5
1
0
0
0
0.5
Space
spacespace
1
1.5
2
2.5
3
VCC (V)
3.5
4
4.5
5
0
5.5
50
100
150
200
250
Cb (pF)
D007
Space
spacespace
Standard-mode
(fSCL= 100 kHz, tr = 1 µs)
Figure 16. Pass-Gate Voltage (Vpass) vs Supply Voltage
(VCC) at Three Temperature Points
300
350
400
450
D008
Fast-mode
(fSCL= 400 kHz, tr= 300 ns)
Figure 17. Maximum Pull-up resistance (Rp(max)) vs Bus
Capacitance (Cb)
1.8
1.6
Rp(min) (kOhm)
1.4
1.2
1
0.8
0.6
0.4
VDPUX > 2V
VDPUX 2 V
Figure 18. Minimum Pull-up Resistance (Rp(min)) vs Pull-up Reference Voltage (VDPUX)
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10 Power Supply Recommendations
The operating power-supply voltage range of the TCA9544A is 1.65 V to 5.5 V applied at the VCC pin. When the
TCA9544A is powered on for the first time or anytime the device needs to be reset by cycling the power supply,
the power-on reset requirements must be followed to ensure the I2C bus logic is initialized properly.
10.1 Power-On Reset Requirements
In the event of a glitch or data corruption, TCA9544A can be reset to its default conditions by using the power-on
reset feature. Power-on reset requires that the device go through a power cycle to be completely reset. This
reset also happens when the device is powered on for the first time in an application.
A power-on reset is shown in Figure 19.
VCC
Ramp-Up
Ramp-Down
VCC_TRR
VCC drops below VPORF – 50 mV
Time
Time to Re-Ramp
VCC_FT
VCC_RT
Figure 19. VCC is Lowered Below the POR Threshold, Then Ramped Back Up to VCC
Table 3 specifies the performance of the power-on reset feature for TCA9544A for both types of power-on reset.
Table 3. Recommended Supply Sequencing And Ramp Rates (1)
PARAMETER
MIN
TYP
MAX
UNIT
VCC_FT
Fall time
See Figure 19
1
ms
VCC_RT
Rise time
See Figure 19
0.1
ms
VCC_TRR
Time to re-ramp (when VCC drops below VPORF(min) – 50 mV or
when VCC drops to GND)
See Figure 19
40
μs
VCC_GH
Level that VCC can glitch down to, but not cause a functional
disruption when VCC_GW = 1 μs
See Figure 20
1.2
V
VCC_GW
Glitch width that will not cause a functional disruption when
VCC_GH = 0.5 × VCC
See Figure 20
10
μs
VPORF
Voltage trip point of POR on falling VCC
See Figure 21
0.8
1.25
V
VPORR
Voltage trip point of POR on rising VCC
See Figure 21
1.05
1.5
V
(1)
All supply sequencing and ramp rate values are measured at TA = 25°C
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Glitches in the power supply can also affect the power-on reset performance of this device. The glitch width
(VCC_GW) and height (VCC_GH) are dependent on each other. The bypass capacitance, source impedance, and
device impedance are factors that affect power-on reset performance. Figure 20 and Table 3 provide more
information on how to measure these specifications.
VCC
VCC_GH
Time
VCC_GW
Figure 20. Glitch Width and Glitch Height
VPOR is critical to the power-on reset. VPOR is the voltage level at which the reset condition is released and all the
registers and the I2C/SMBus state machine are initialized to their default states. The value of VPOR differs based
on the VCC being lowered to or from 0. Figure 21 and Table 3 provide more details on this specification.
VCC
VPORR
VPORF
Time
POR
Time
Figure 21. VPOR
20
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11 Layout
11.1 Layout Guidelines
For PCB layout of the TCA9544A, common PCB layout practices should be followed but additional concerns
related to high-speed data transfer such as matched impedances and differential pairs are not a concern for I2C
signal speeds. It is common to have a dedicated ground plane on an inner layer of the board and pins that are
connected to ground should have a low-impedance path to the ground plane in the form of wide polygon pours
and multiple vias. By-pass and de-coupling capacitors are commonly used to control the voltage on the VCC pin,
using a larger capacitor to provide additional power in the event of a short power supply glitch and a smaller
capacitor to filter out high-frequency ripple.
In an application where voltage translation is not required, all VDPUX voltages and VCC could be at the same
potential and a single copper plane could connect all of pull-up resistors to the appropriate reference voltage. In
an application where voltage translation is required, VDPUM, VDPU0, VDPU1, VDPU2, and VDPU3 may all be on the
same layer of the board with split planes to isolate different voltage potentials.
To reduce the total I2C bus capacitance added by PCB parasitics, data lines (SCn, SDn and INTn) should be a
short as possible and the widths of the traces should also be minimized (e.g. 5-10 mils depending on copper
weight).
11.2 Layout Example
LEGEND
Partial Power Plane
Polygonal
Copper Pour
To I2C Master
VIA to Power Plane
VIA to GND Plane (Inner Layer)
VDPUM
Bypass/Decoupling
Capacitors
VCC
A1
SDA
A2
SCL
INT0
SD0
SC0
VDPU3
INT
SC3
SD3
INT3
SD1
SC2
SC1
SD2
GND
INT2
GND
VDPU2
To Slave Channel 2
To Slave Channel 1
INT1
VDPU1
VCC
A0
TCA9544A
VDPU0
To Slave Channel 3
To Slave Channel 1
GND
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12 Device and Documentation Support
12.1 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
12.2 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do
not necessarily reflect TI's views; see TI's Terms of Use.
12.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TCA9544APWR
ACTIVE
TSSOP
PW
20
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
PW544A
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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