LTC4306
4-Channel,
2-Wire Bus Multiplexer with
Capacitance Buffering
FEATURES
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■
■
■
■
■
■
■
■
■
■
DESCRIPTIO
1:4 2-Wire Multiplexer/Switch
Connect SDA and SCL Lines with 2-Wire Bus
Commands
Supply Independent Bidirectional Buffer for SDA
and SCL Lines Increases Fan-Out
Programmable Disconnect from Stuck Bus
Compatible with I
2
C and SMBus Standards
Rise Time Accelerator Circuitry
SMBus Compatible ALERT Response Protocol
Two General Purpose Inputs-Outputs
Prevents SDA and SCL Corruption During Live Board
Insertion and Removal from Backplane
±10kV
Human Body Model ESD Ruggedness
24-Lead QFN (4mm
×
5mm) and SSOP Packages
The LTC
®
4306 is a 4-channel, 2-wire bus multiplexer with
bus buffers to provide capacitive isolation between the
upstream bus and downstream buses. Through software
control, the LTC4306 connects the upstream 2-wire bus to
any desired combination of downstream buses. Each
channel can be pulled up to a supply voltage ranging from
2.2V to 5.5V, independent of the LTC4306 supply voltage.
The downstream channels are also provided with
ALERT1-ALERT4 inputs for fault reporting.
Programmable timeout circuitry disconnects the down-
stream buses if the bus is stuck low. When activated, rise
time accelerators source currents into the 2-wire bus pins
to reduce rise time. Driving the ENABLE pin low restores
all features to their default states. Three address pins
provide 27 distinct addresses.
The LTC4306 is available in 24-lead QFN (4mm
×
5mm)
and SSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patent pending.
APPLICATIO S
■
■
■
Nested Addressing
5V/3.3V Level Translator
Capacitance Buffer/Bus Extender
TYPICAL APPLICATIO
2.5V
3.3V
A Level Shifting and Nested Addressing Application
I
2
C Bus Waveforms
V
CC
= 3.3V
0.01µF
10k
10k
10k
V
CC
MICRO-
CONTROLLER
SCLIN
SDAIN
ALERT
SCL1
SDA1
ALERT1
5V
SFP
MODULE 1
ADDRESS = 1111 000
LTC4306
10k
10k
10k
SCLIN
2V/DIV
SCL1
2V/DIV
•
•
•
10k
10k
10k
SFP
MODULE 4
SCL4
2V/DIV
500ns/DIV
VCARD4 = 5V
ADR2
ADR1
ADR0
GND
SCL4
SDA4
ALERT4
4306 TA01a
ADDRESS = 1111 000
ADDRESS = 1000 100
U
VBACK = 2.5V
VCARD1 = 3.3V
4306 TA01b
U
U
4306f
1
LTC4306
ABSOLUTE
AXI U
RATI GS
Supply Voltage (V
CC
) ................................... –0.3V to 7V
Input Voltages (ADR0, ADR1, ADR2,
ENABLE, ALERT1, ALERT2, ALERT3,
ALERT4) .................................................. –0.3V to 7V
Output Voltages (ALERT, READY) ............... –0.3V to 7V
Input/Output Voltages (SDAIN, SCLIN,
SCL1, SDA1, SCL2, SDA2, SCL3,
SDA3, SCL4, SDA4, GPIO1, GPIO2) ........ –0.3V to 7V
Output Sink Currents (SDAIN, SCLIN, SCL1-4, SDA1-4,
GPI01-2, ALERT, READY) ..................................... 10mA
PACKAGE/ORDER I FOR ATIO
TOP VIEW
ALERT2
SDA3
SDA2
SCL3
SCL2
ORDER PART
NUMBER
19 ALERT3
18 ALERT1
17 SDA1
24 23 22 21 20
ALERT 1
SDAIN 2
GND 3
SCLIN 4
ENABLE 5
V
CC
6
ALERT4 7
8
9 10 11 12
25
LTC4306CUFD
LTC4306IUFD
16 SCL1
15 SCL4
14 SDA4
13 READY
UF PART MARKING*
4306
GPIO1
ADR0
ADR1
GPI02
ADR2
UFD PACKAGE
24-LEAD (4mm
×
5mm) PLASTIC QFN
EXPOSED PAD (PIN 25), PCB CONNECTION OPTIONAL
MUST BE CONNECTED TO THE PCB TO OBTAIN
θ
JA
= 43°C/W OTHERWISE
θ
JA
= 140°C/W. T
JMAX
= 125°C
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
I
CC
I
CC ENABLE
= 0V
V
UVLOU
PARAMETER
Input Supply Range
Input Supply Current
Input Supply Current
UVLO Upper Threshold Voltage
Power Supply/Start-Up
The
●
denotes specifications which apply over the full specified temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V unless otherwise noted.
CONDITIONS
●
Downstream Connected, SCL Bus Low,
SDA Bus High, V
CC
= 5.5V
V
ENABLE
= 0V, V
CC
= 5.5V
2
U
U
W
W W
U
W
(Note 1)
Operating Temperature Range
LTC4306C ............................................... 0°C to 70°C
LTC4306I ............................................. –40°C to 85°C
Storage Temperature Range
SSOP ................................................. –65°C to 150°C
QFN ................................................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec)
SSOP ................................................................ 300°C
TOP VIEW
SCL3
SDA3
ALERT
SDAIN
GND
SCLIN
ENABLE
V
CC
ALERT4
1
2
3
4
5
6
7
8
9
24 ALERT2
23 SCL2
22 SDA2
21 ALERT3
20 ALERT1
19 SDA1
18 SCL1
17 SCL4
16 SDA4
15 READY
14 ADR2
13 ADR1
ORDER PART
NUMBER
LTC4306CGN
LTC4306IGN
GPI01 10
GPI02 11
ADR0 12
GN PACKAGE
24-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 85°C/W
MIN
2.7
TYP
MAX
5.5
UNITS
V
mA
mA
V
4306f
●
●
●
5.2
1.25
2.3
2.5
8
2.5
2.7
LTC4306
The
●
denotes specifications which apply over the full specified temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V unless otherwise noted.
SYMBOL
V
UVLOHYST
V
TH EN
V
ENHYST
t
PHLEN
t
PLHEN
I
INEN
V
LOWREADY
I
OFFREADY
V
OS,BUF
V
OS,UP-BUF
V
OS,DOWN-BUF
V
OL
PARAMETER
UVLO Threshold Hysteresis Voltage
ENABLE Falling Threshold Voltage
ENABLE Threshold Hysteresis Voltage
ENABLE Delay, On-Off
ENABLE Delay, Off-On
ENABLE Input Leakage Current
READY Pin Logic Low Output Voltage
READY Off State Input Leakage Current
Buffer Offset Voltage
Upstream Buffer Offset Voltage
V
IN, BUFFER
= 0V
Downstream Buffer Offset Voltage
V
IN, BUFFER
= 0V
Output Low Voltage, V
IN,BUFFER
= 0V
Output Low Voltage, V
IN,BUFFER
= 0.2V
V
IL,MAX
V
THSDA,SCL
I
LEAK
Buffer Input Logic Low Voltage
Downstream SDA, SCL Logic Threshold Voltage
Input Leakage Current
SDA, SCL Pins; V
CC
= 0V to 5.5V;
Buffers Inactive
SDAIN, SCLIN, SDA1-4, SCL1-4 Pins
SDAIN, SCLIN, SDA1-4, SCL1-4 Pins
SDAIN, SCLIN, SDA1-4, SCL1-4 Pins
(Note 3)
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
●
●
MIN
100
0.8
TYP
175
1.0
60
60
20
MAX
250
1.2
UNITS
mV
V
mV
ns
ns
V
ENABLE
= 0V, 5.5V, V
CC
= 5.5V
I
PULL-UP
= 3mA, V
CC
= 2.7V
V
READY
= 0V, 5.5V, V
CC
= 5.5V
R
BUS
= 10k, V
CC
= 2.7V, 5.5V (Note 4)
V
CC
= 2.7V, R
BUS
= 2.7k (Note 4)
V
CC
= 5.5V, R
BUS
= 2.7k (Note 4)
V
CC
= 2.7V, R
BUS
= 2.7k (Note 4)
V
CC
= 5.5V, R
BUS
= 2.7k (Note 4)
SDA, SCL Pins; I
SINK
= 4mA,
V
CC
= 3V, 5.5V
SDA, SCL Pins; I
SINK
= 500µA,
V
CC
= 2.7V, 5.5V
V
CC
= 2.7V, 5.5V
●
●
●
●
●
●
●
●
●
●
●
●
●
0
0.18
0
25
40
70
60
80
60
80
110
110
140
±
1
0.4
±
1
100
120
150
160
200
400
320
µA
V
µA
mV
mV
mV
mV
mV
mV
mV
V
V
µA
Upstream-Downstream Buffers
0.4
0.8
0.52
1.0
0
0.64
1.2
±
5
Rise Time Accelerators
V
SDA,SCL slew
V
RISE,DC
I
BOOST
GPIOs
V
GPIO(TH)
V
GPIO(OL)
V
GPIO(OH)
I
GPIO(IN)
V
TIMER(L)
V
TIMER(HYST)
T
TIMER1
T
TIMER2
T
TIMER3
ALERT
V
ALERT(OL)
I
OFF,ALERT
I
IN,ALERT1-4
ALERT Output Low Voltage
ALERT Off State Input Leakage Current
ALERT1-ALERT4 Input Current
I
ALERT
= 3mA, V
CC
= 2.7V
V
ALERT
= 0V, 5.5V
V
ALERT1-4
= 0V, 5.5V
●
●
●
Minimum Slew Requirement to Activate
Rise Time Accelerator Currents
Rise Time Accelerator DC Threshold Voltage
Rise Time Accelerator Pull-Up Current
●
●
0.4
0.7
4
0.8
5.5
0.8
1
V/µs
V
mA
GPIO Pin Input Threshold
GPIO Pin Output Low Voltage
GPIO Pin Output High Voltage
GPIO Pin Input Leakage Current
Stuck Low Falling Threshold Voltage
Stuck Low Threshold Hysteresis Voltage
Timeout Time #1
Timeout Time #2
Timeout Time #3
TIMSET1,0 = 01
TIMSET1,0 = 10
TIMSET1,0 = 11
I
GPIO
= 5mA, V
CC
= 2.7V
I
GPIO
= –200µA, V
CC
= 2.7V
V
GPIO
= 0V, 5.5V, V
CC
= 5.5V
V
CC
= 2.7V, 5.5V
0.8
V
CC
– 0.3
1
0.2
0
1.2
0.4
±
1
0.64
35
17.5
8.75
0.4
±
1
±
1
V
V
V
µA
V
mV
ms
ms
ms
V
µA
µA
4306f
●
●
●
●
●
●
●
Stuck Low Timeout Circuitry
0.4
25
12.5
6.25
0.52
80
30
15
7.5
0.2
0
0
3
LTC4306
The
●
denotes specifications which apply over the full specified temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V unless otherwise noted.
SYMBOL
V
ALERT1-4(IN)
V
ALERT1-4(HY)
I
2
C Interface
V
ADR(H)
V
ADR(L)
I
ADR(IN, L)
I
ADR(FLOAT)
I
ADR(IN, H)
ADR0-2 Input High Voltage
ADR0-2 Input Low Voltage
ADR0-2 Logic Low Input Current
ADRO-2 Allowed Input Current
ADR0-2 Logic High Input Current
ADR0-2 = 0V, V
CC
= 5.5V
V
CC
= 2.7V, 5.5V (Note 5)
ADR0-2 = V
CC
= 5.5V
V
CC
= 5.5V
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
PARAMETER
ALERT1-ALERT4 Pin Input Falling
Threshold Voltages
ALERT1-ALERT4 Pin Input Threshold
Hysteresis Voltages
CONDITIONS
●
MIN
0.8
TYP
1.0
80
MAX
1.2
UNITS
V
mV
0.75 • V
CC
0.9 • V
CC
0.1 • V
CC
0.25 • V
CC
–30
±5
30
1.4
–60
±13
60
1.6
30
80
1.8
–80
V
V
µA
µA
µA
V
mV
V
SDAIN,SCLIN(TH)
SDAIN, SCLIN Input Falling Threshold
Voltages
V
SDAIN,SCLIN(HY)
SDAIN, SCLIN Hysteresis
I
SDAIN,SCLIN(OH)
SDAIN, SCLIN Input Current
C
IN
V
SDAIN(OL)
f
SCL
t
BUF
t
HD,STA
t
SU,STA
t
SU,STO
t
HD,DATI
t
HD,DATO
t
SU,DAT
t
f
t
SP
SDA, SCL Input Capacitance
SDAIN Output Low Voltage
Maximum SCL Clock Frequency
Hold Time After (Repeated) Start Condition
Repeated Start Condition Set-up Time
Stop Condition Set-up Time
Data Hold Time Input
Data Hold Time Output
Data Set-up Time
SCL, SDA Fall Times
Pulse Width of Spikes Suppressed by the
Input Filter
SCL, SDA = V
CC
(Note 2)
I
SDA
= 4mA, V
CC
= 2.7V
(Note 2)
(Note 2)
(Note 2)
(Note 2)
(Note 2)
(Note 2)
(Note 2)
(Note 2)
(Note 2)
●
●
0
6
0.2
400
0.75
45
–30
–30
–25
300
20 + 0.1
•
C
BUS
50
150
600
50
±
5
0.4
µA
pF
V
kHz
I
2
C Interface Timing
Bus Free Time Between Stop/Start Condition (Note 2)
1.3
100
0
0
0
900
100
300
250
µs
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Guaranteed by design and not subject to test.
Note 3:
The boosted pull-up currents are regulated to prevent excessively
fast edges for light loads. See the Typical Performance Characteristics for
rise time as a function of V
CC
and parasitic bus capacitance C
BUS
and for
I
BOOST
as a function of V
CC
and temperature.
Note 4:
When a logic low voltage, V
LOW
, is forced on one side of the
Upstream-Downstream Buffers, the voltage on the other side is regulated
to a voltage V
LOW2
= V
LOW
+ V
OS
, where V
OS
is a positive offset voltage.
V
OS,UP-BUF
is the offset voltage when the LTC4306 is driving the upstream
pin (e.g., SDAIN) and V
OS,DOWN-BUF
is the offset voltage when the
LTC4306 is driving the downstream pin (e.g., SDA1). See the Typical
Performance Characteristics for V
OS,UP-BUF
and V
OS,DOWN-BUF
as a
function of V
CC
and bus pull-up current.
Note 5:
When floating, the ADR0-ADR2 pins can tolerate pin leakage
currents up to I
ADR(FLOAT)
and still convert the address correctly.
4306f
4
LTC4306
TYPICAL PERFOR A CE CHARACTERISTICS
Buffer Circuitry t
PHL
vs Temperature
120
100
V
CC
= 3.3V
t
PHL
(ns)
V
CC
= 5V
60
40
20
0
–50 –25
RISE TIME (ns)
150
V
CC
= 5V
CURRENT (mA)
80
50
25
75
0
TEMPERATURE (°C)
V
OS,UP-BUF
vs Bus Pull-Up Current
180
160
250
140
120
V
OS
(mV)
V
OS
(mV)
V
CC
= 3.3V
V
CC
= 5V
100
80
60
40
20
0
0
3
1
2
BUS PULL-UP CURRENT (mA)
0
4
4306 G04
Downstream R
FET
On Resistance
vs V
CC
and Temperature
45
40
35
30
I
BOOST
(mA)
R
ON
(Ω)
V
CC
= 3.3V
25
20
15
V
CC
= 5V
10
5
0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
U W
100
4306 G01
(T
A
= 25°C, unless otherwise indicated)
Rise Time vs C
BUS
vs V
CC
250
dV = 0.3V • V
CC
TO 0.7V • V
CC
R
BUS
= 10k
V
CC
= 3.3V
I
CC
vs Temperature
6
V
CC
= 5V
5
4
3
2
1
0
–50 –25
UPSTREAM CONNECTED TO CHANNEL 1,
SCL BUS LOW, SDA BUS HIGH
50
25
75
0
TEMPERATURE (°C)
100
125
V
CC
= 3.3V
200
100
50
125
0
0
200
600
800
400
CAPACITANCE, C
BUS
(pF)
1000
4306 G02
4306 G03
V
OS,DOWN-BUF
vs Bus Pull-Up Current
300
200
V
CC
= 3.3V
150
V
CC
= 5V
100
50
0
1
2
3
BUS PULL-UP CURRENT (mA)
4
4306 G05
I
BOOST
vs Temperature
14
12
10
V
CC
= 5V
8
6
V
CC
= 3.3V
4
2
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
4306 G06
4306 G07
4306f
5
PCB设计
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