LINER LTC4308 Pin-selectable, 4-channel, 2-wire multiplexer with bus buffer Datasheet

LTC4314
Pin-Selectable, 4-Channel,
2-Wire Multiplexer
with Bus Buffers
DESCRIPTION
FEATURES
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The LTC®4314 is a hot-swappable 4-channel 2-wire bus
multiplexer that allows one upstream bus to connect to
any combination of downstream busses or channels.
An individual enable pin controls each connection. The
LTC4314 provides bidirectional buffering, keeping the upstream bus capacitance isolated from the downstream bus
capacitances. The high noise margin allows the LTC4314
to be interoperable with I2C devices that drive a high VOL
(> 0.4V). The LTC4314 supports level translation between
1.5V, 1.8V, 2.5V, 3.3V and 5V busses. The hot-swappable
nature of the LTC4314 allows I/O card insertion into, and
removal from, a live backplane without corruption of the
data and clock busses.
1:4 Multiplexer/Switch for 2-Wire Bus
Bidirectional Buffer for SDA and SCL Lines
High Noise Margin with VIL = 0.3•VCC
ENABLE Pins Connect SDA and SCL Lines
Selectable Rise Time Accelerator Current and
Activation Voltage
Level Shift 1.5V, 1.8V, 2.5V, 3.3V and 5V Busses
Prevents SDA and SCL Corruption During Live Board
Insertion and Removal from Backplane
Stuck Bus Disconnect and Recovery
Compatible with I2C, I2C Fast Mode and SMBus
±4kV Human Body Model (HBM) ESD Ruggedness
20-Lead SSOP and 3mm × 4mm QFN Packages
If both data and clock are not simultaneously high at
least once in 45ms and DISCEN is high, a FAULT signal is
generated indicating a stuck bus low condition, the input
is disconnected from all enabled output channels, and up
to 16 clocks are generated on the enabled downstream
busses. A three state ACC pin enables input and output
side rise time accelerators of varying strengths and sets
the VIL,RISING voltage.
APPLICATIONS
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Telecommunications Systems Including ATCA
Address Expansion
Level Translator
Capacitance Buffers/Bus Extender
Live Board Insertion
PMBus
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot Swap
is a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents, including 6356140, 6650174, 7032051, 7478286.
TYPICAL APPLICATION
0.01μF
10k
10k
3.3V
VCC2
VCC
SCLIN
SCLIN
SDAIN
SDAIN
Rising Edge from Asserted Low
with Level Translation
10k
10k
0.01μF
SCLOUT1
SCLOUT1
ENABLE2
SDAOUT1
SDAOUT1
ENABLE3
ENABLE3
ENABLE4
ENABLE4
3.3V
LTC4314
SCLOUT4
5V
3.3V
SCLIN
10k
ACC
SCLOUT4
SCLOUT4
DISCEN
SDAOUT4
SDAOUT4
FAULT
CSCLOUT1 + CSCLOUT4 = 100pF
CSCLIN = 50pF
SCLOUT1
5V
10k
10k
FAULT
• • •
ENABLE1
ENABLE2
• • •
ENABLE1
6V
1V/DIV
3.3V
0V
200ns/DIV
4314 TA01b
GND
4314 TA01a
4314f
1
LTC4314
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltages
VCC, VCC2 ................................................. –0.3V to 6V
Input Voltages
ACC, DISCEN, ENABLE1-4 ....................... –0.3V to 6V
Input/Output Voltages
SDAIN, SCLIN, SCLOUT1-4,
SDAOUT1-4, FAULT ................................. –0.3V to 6V
Output DC Sink Currents
FAULT.................................................................50mA
Operating Ambient Temperature Range
LTC4314C ................................................ 0°C to 70°C
LTC4314I..............................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
SSOP ............................................................... 300°C
PIN CONFIGURATION
TOP VIEW
GND
ACC
DISCEN
VCC
TOP VIEW
20 19 18 17
SCLOUT1 1
16 SDAOUT4
SDAOUT1 2
15 SCLOUT4
SDAIN 3
14 VCC2
21
SCLIN 4
13 FAULT
11 SCLOUT3
8
9 10
ENABLE1
7
ENABLE2
SDAOUT2 6
ENABLE 3
12 SDAOUT3
ENABLE4
SCLOUT2 5
DISCEN
1
20 ACC
VCC
2
19 GND
SCLOUT1
3
18 SDAOUT4
SDAOUT1
4
17 SCLOUT4
SDAIN
5
16 VCC2
SCLIN
6
15 FAULT
SCLOUT2
7
14 SDAOUT3
SDAOUT2
8
13 SCLOUT3
ENABLE4
9
12 ENABLE1
ENABLE3 10
11 ENABLE2
GN PACKAGE
20-LEAD PLASTIC SSOP
TJMAX = 150°C, θJA = 90°C/W, θJC = 30°C/W
UDC PACKAGE
20-LEAD (3mm s 4mm) PLASTIC QFN
TJMAX = 150°C, θJA = 68°C/W, θJC = 4.2°C/W
EXPOSED PAD (PIN 21) PCB CONNECTION TO GND IS OPTIONAL
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4314IUDC#PBF
LTC4314IUDC#TRPBF
LTC4314IGN#PBF
LTC4314IGN#TRPBF
LFMR
20-Lead (3mm × 4mm) QFN
–40°C to 85°C
LTC4314GN
20-Lead Plastic SSOP
–40°C to 85°C
LTC4314CUDC#PBF
LTC4314CUDC#TRPBF
LFMR
20-Lead (3mm × 4mm) QFN
0°C to 70°C
LTC4314CGN#PBF
LTC4314CGN#TRPBF
LTC4314GN
20-Lead Plastic SSOP
0°C to 70°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
4314f
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LTC4314
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = VCC2 = 3.3V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply/Start-Up
VCC
Input Supply Voltage
l
2.9
5.5
V
VDD, BUS
2-Wire Bus Supply Voltage
l
2.25
5.5
V
VCC2
Output Side Accelerator Supply
Voltage
l
2.25
5.5
V
ICC
Input Supply Current
One or More VENABLE1-4 = VCC = VCC2 = 5.5V
(Note 3)
l
6.0
7.3
9
mA
ICC(DISABLED)
Input Supply Current
VENABLE1-4 = 0V, VCC = VCC2 = 5.5V (Note 3)
l
1.6
2.2
3.5
mA
ICC2
VCC2 Supply Current
One or More VENABLE1-4 = VCC = VCC2 = 5.5V
(Note 3)
l
0.35
0.5
0.6
mA
tUVLO
UVLO Delay
l
60
110
200
μs
VTH_UVLO
UVLO Threshold
l
2.3
2.6
V
VCC_UVLO(HYST) UVLO Threshold Hysteresis Voltage
200
mV
Buffers
VOS(SAT)
Buffer Offset Voltage
VOS2(SAT)
Buffer Offset Voltage
VOS
VOS2
Buffer Offset Voltage
Buffer Offset Voltage
IOL = 4mA, Driven VSDAIN, SCLIN = 50mV
l
130
IOL = 500μA, Driven VSDAIN, SCLIN = 50mV
l
IOL = 4mA, Driven VSDAOUT, SCLOUT = 50mV
l
IOL = 500μA, Driven VSDAOUT, SCLOUT = 50mV
220
280
mV
15
60
120
mV
90
190
260
mV
l
15
55
110
mV
IOL = 4mA, Driven VSDAIN, SCLIN = 200mV
l
50
130
195
mV
IOL = 500μA, Driven VSDAIN, SCLIN = 200mV
l
15
55
110
mV
IOL = 4mA, Driven VSDAOUT,SCLOUT = 200mV
l
35
95
170
mV
15
50
100
mV
IOL = 500μA, Driven VSDAOUT,SCLOUT = 200mV
l
VIL,FALLING
Buffer Input Logic Low Voltage
SDA, SCL Pins (Notes 4, 5)
l
VIL,RISING
Buffer Input Logic Low Voltage
SDA, SCL Pins; ACC Grounded
l
SDA, SCL Pins; ACC Open or High (Notes 4, 5)
l
ILEAK
Input Leakage Current
SDA, SCL Pins; VCC , VCC2 = 0V, 5.5V
l
CIN
Input Capacitance
SDA, SCL Pins (Note 6)
0.3•VMIN 0.33•VMIN 0.36•VMIN
0.5
0.6
0.7
0.3•VMIN 0.33•VMIN 0.36•VMIN
V
V
V
±10
μA
<20
pF
Rise Time Accelerators
dV/dt (RTA)
Minimum Slew Rate Requirement
SDA, SCL Pins; VCC = VCC2 = 5V
l
0.1
0.2
0.4
V/μs
VRTA(TH)
Rise Time Accelerator DC
Threshold Voltage
SDA, SCL Pins; VCC = VCC2 = 5V, ACC Grounded
l
0.7
0.8
0.9
V
ACC Open or High, VCC = VCC2 = 5V (Note 4)
l 0.36•VMIN 0.4•VMIN 0.44•VMIN
ΔVACC
IRTA
Buffers Off to Accelerator On Voltage SDA, SCL Pins; VCC = VCC2 = 5V, ACC Grounded
Rise Time Accelerator
Pull-Up Current
l
100
200
V
mV
ACC Open, VCC = VCC2 = 5V (Note 4)
l 0.05•VMIN 0.07•VMIN
SDA, SCL Pins; VCC = VCC2 = 5V,
ACC Grounded (Note 7)
l
20
35
45
mA
ACC Open, VCC = VCC2 = 5V (Note 7)
l
1.5
3
4
mA
l
0.8
1.4
2
V
mV
Enable/Control
VDISCEN(TH)
DISCEN Threshold Voltage
ΔVDISCEN(HYST) DISCEN Hysteresis Voltage
VEN(TH)
ENABLE1-4 Threshold Voltage
ΔVEN(HYST)
ENABLE1-4 Hysteresis Voltage
20
l
0.8
1.4
20
mV
2
V
mV
4314f
3
LTC4314
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = VCC2 = 3.3V unless otherwise noted.
SYMBOL
PARAMETER
tLH_EN
ENABLE1-4 High to Buffer Active
ILEAK
Input Leakage Current
IACC(IN, HL)
CONDITIONS
TYP
MAX
l
MIN
0.56
1
UNITS
μs
DISCEN = ENABLE1–4 Pins = 5.5V
l
0.1
±10
μA
ACC High, Low Input Current
VCC = 5V, VACC = 5V, 0V
l
±23
±40
μA
IACC(IN, Z)
Allowable Leakage Current in
Open State
VCC = 5V
l
±5
μA
IACC(EN, Z)
ACC High Z Input Current
VCC = 5V
l
±5
VACC(L, TH)
ACC Input Low Threshold Voltages
VCC = 5V
l
0.2•VCC
0.3•VCC
0.4•VCC
V
VACC(H,TH)
ACC Input High Threshold Voltages
VCC = 5V
l
0.7•VCC
0.8•VCC
0.9•VCC
V
35
45
55
ms
0.4
V
±5
μA
μA
Stuck Low Timeout Circuitry
tTIMEOUT
Bus Stuck Low Timer
SDAOUT or SCLOUT < 0.3•VCC
l
VFAULT(OL)
FAULT Output Low Voltage
I FAULT = 3mA
l
IFAULT(OH)
FAULT Leakage Current
l
0.1
I2C Interface Timing
fSCL(MAX)
I2C Frequency Max
(Note 6)
tPDHL
SCL, SDA Fall Delay
VCC = 3V to 5.5V, CBUS = 50pF, IBUS = 1mA (Note 6)
60
tf
SCL, SDA Fall Times
VCC = 3V to 5.5V, CBUS = 50pF, IBUS = 1mA (Note 6)
10
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into pins are positive and all voltages are referenced to
GND unless otherwise indicated.
Note 3: SDAIN, SCLIN pulled low.
Note 4: VMIN = minimum of VCC and VCC2 if VCC2 > 2.25V else VMIN = VCC.
l
400
kHz
100
ns
ns
Note 5: VIL is tested for the following (VCC, VCC2) combinations:
(2.9V, 5.5V), (5.5V, 2.25V), (3.3V, 3.3V) and (5V, 0V).
Note 6: Guaranteed by design and not tested.
Note 7: Measured in a special DC mode with VSDA,SCL = VRTA(TH) + 1V.
The transient IRTA seen during rising edges when ACC is low will depend
on the bus loading condition and the slew rate of the bus. The LTC4314’s
internal slew rate control circuitry limits the maximum bus rise rate to
75V/μs by controlling the transient IRTA.
4314f
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LTC4314
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, VCC = 3.3V unless otherwise noted.
ICC Disabled (ENABLE1-4 Low)
Current vs Supply Voltage
ICC Enabled Current
vs Supply Voltage
8.0
Multiplexer Switch Resistance
RMUX vs Temperature
10
3.0
VSDAIN, SCLIN = 0V
IDS = 4mA
VSDAIN, SCLIN = 0V
9
VCC2 = 3.3V
2.5
8
RMUX (Ω)
ICC (mA)
ICC (mA)
7.5
2.0
7
VCC2 = 5V
6
7.0
1.5
5
6.5
3
2
4
5
1.0
6
3
2
4
VCC (V)
5
VCC (V)
4314 G01
250
VCC = VCC2 = 3.3V
100
Input to Output Offset Voltage
vs Bus Current for Different
Driven Input Voltage Levels
350
VCC = VCC2 = VDD, BUS = 5V
RBUS = 2.7kΩ
VCC = VCC2 = VDD, BUS = 5V
300
DRIVEN VSDAIN, SCLIN = 50mV
250
VSDAIN, SCLIN = 0.4V
7
VSDAOUT, SCLOUT = 0.4V
6
150
VOS (mV)
tPDF (ns)
IOL (mA)
75
200
8
100
200
100mV
150
≥200mV
100
50
5
4
–50
–25
25
0
50
TEMPERATURE (°C)
75
0
100
50
0
500
0
1000
1500
tRISE(30%–70%) vs CBUS
16
150
VCC = VCC2 = VDD, BUS = 5V
VCC = VCC2 = VDD, BUS
VSDA,SCLtVDD,BUS
ACC = 0V
CBUS = 400pF
RBUS = 10k
300
14
5V
250
100
12
10
8
2
4
6
IBUS (mA)
4314 G07
6
–50
5V
75
3.3V
25
50
0
100
50
3.3V
≥200mV
VCC = VCC2 = VDD, BUS
ACC = 0V
125
tRISE (ns)
IRTA (mA)
DRIVEN VSDAOUT, SCLOUT = 50mV
100mV
6
4314 G06
Rise Time Accelerator Current
vs Temperature
350
150
4
IBUS (mA)
4314 G05
Output to Input Offset Voltage
vs Bus Current for Different
Driven Output Voltage Levels
200
2
0
CBUS (pF)
4314 G04
VOS (mV)
0
50
25
TEMPERATURE (°C)
4314 G03
Buffer High to Low Propagation
Delay vs Output Capacitance
9
0
–25
4314 G02
Buffer DC IOL vs Temperature
10
4
–50
6
–25
25
50
0
TEMPERATURE (°C)
75
100
4314 G08
0
0
200
400
CBUS (pF)
600
800
4314 G08
4314f
5
LTC4314
PIN FUNCTIONS
ACC: Three-State Acceleration and Buffer Mode Selector. This pin controls the turn on voltage of the rise time
accelerators and their current strength on both the input
and output sides. It also controls the turn-off voltage of
the buffers. See Table 1 in the Applications Information
section.
DISCEN: Disconnect Stuck Bus Enable Input. When this
pin is high, stuck busses are automatically disconnected
and FAULT is pulled low after a timeout period of 45ms.
Up to sixteen clock pulses are subsequently applied to the
stuck output channels. When DISCEN is low, stuck busses
are neither disconnected nor clocked but FAULT is pulled
low. Connect to GND if unused.
ENABLE1-ENABLE4: Connection Enable Inputs. These
input pins enable or disable the corresponding output
channel. Driving an ENABLE pin low isolates SDAIN and
SCLIN from the corresponding SDAOUT and SCLOUT.
Only enable and disable a channel when all busses are
idle. During bus stuck low fault condition, a falling edge
on all ENABLE pins followed by a rising edge on one or
more ENABLE pins forces a connection from SDAIN to
the selected SDAOUT and SCLIN to the selected SCLOUT.
Connect to GND if unused.
Exposed Pad (QFN Package Only): Exposed pad may be
left open or connected to device GND.
FAULT: Stuck Bus Fault Output. This open drain N-channel
MOSFET output pulls low if a simultaneous high on the
enabled SCLOUT and SDAOUT channels does not occur in
45ms. In normal operation FAULT is high. Connect a pull
up resistor, typically 10k, from this pin to the bus pull-up
supply. Leave open or tie to GND if unused.
GND: Device Ground.
SCLIN: Upstream Serial Bus Clock Input/Output. Connect
this pin to the SCL line on the upstream bus. Connect an
external pull-up resistor or current source between this
pin and the bus supply. Do not leave open.
SCLOUT1-SCLOUT4: Downstream Serial Bus Clock Input/
Output Channels 1-4. Connect pins SCLOUT1-SCLOUT4
to the SCL lines on the downstream channels 1-4, respectively. When in use, an external pull-up resistor or current
source is required between the pin and the corresponding
bus supply. Leave open or tie to GND and connect the
corresponding ENABLE pin to GND if unused.
SDAIN: Upstream Serial Bus Data Input/Output. Connect
this pin to the SDA line on the upstream bus. Connect an
external pull-up resistor or current source between this
pin and the bus supply. Do not leave open.
SDAOUT1-SDAOUT4: Downstream Serial Bus Data Input/
Output Channels 1-4. Connect pins SDAOUT1-SDAOUT4 to
the SDA lines on downstream channels 1-4, respectively.
When in use, an external pull-up resistor or current source
is required between the pin and the corresponding bus
supply. Leave open or tie to GND and connect the corresponding ENABLE pin to GND if unused.
VCC: Power Supply Voltage. Power this pin from a supply between 2.9V and 5.5V. Bypass with at least 0.01μF
to GND.
VCC2: Output Side Rise Time Accelerator (RTA) Power
Supply Voltage. When powering VCC2, use a supply voltage ranging from 2.25V to 5.5V and bypass with at least
0.01μF to GND. If the downstream busses are powered
from multiple supply voltages, power VCC2 from the lowest supply voltage. Output side RTAs are active if VCC2 ≥
2.25V and ACC is low or open. Grounding VCC2 disables
output side RTAs.
4314f
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LTC4314
BLOCK DIAGRAM
VCC
IRTA
VCC2
IRTA
CO1
SCLIN
SCLOUT1
VCC2
CIN
SLEW RATE
DETECTOR
0.2V/μs
VCC
t t t
t t t
SLEW RATE
DETECTOR
0.2V/μs
IRTA
CO4
IRTA
SCLOUT4
VCC2
MUX
IRTA
SDAIN
DO1
DIN
SDAOUT1
VCC2
t t t
t t t
SLEW RATE
DETECTOR
0.2V/μs
SLEW RATE
DETECTOR
0.2V/μs
IRTA
+
VIL
CONNECT
–
VIL
–
LOGIC
45ms
TIMER
–
UVLO
VCC
ttt
SDAOUT4
EN4
VCC2
VIL
+
–
GND
EN1
+
+
DO4
VIL
110μs
TIMER
FAULT
ACC
IBOOST_SCL / IBOOST_SDA
DISCEN
ENABLE1
ttt
ENABLE4
4314 BD
4314f
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LTC4314
OPERATION
The Block Diagram shows the major functional blocks of
the LTC4314. The LTC4314 is a 1:4 multiplexer with capacitance buffering for I2C signals. Capacitance buffering
is achieved by use of back to back buffers on the clock
and data channels which isolate the SDAIN and SCLIN
capacitances from the SDAOUT and SCLOUT capacitances
respectively. All SDA and SCL pins are fully bidirectional.
The high noise margin allows the LTC4314 to operate
with I2C devices that drive a non-compliant high VOL.
Multiplexing is done using N-channel MOSFETs that are
controlled by dedicated ENABLE pins. When enabled,
rise time accelerator pull-up currents IRTA turn on during rising edges to reduce system rise time. In a typical
application the input side bus is pulled up to VCC and the
output side busses are pulled up to VCC2 although these
are not requirements. VCC is the primary power supply to
the LTC4314. VCC and VCC2 serve as the input and output
side rise time accelerator supplies respectively. Grounding VCC2 disables the output side rise time accelerators.
The multiplexer N-channel MOSFET gates of the enabled
channels are driven to VCC2 if VCC2 is > 1.8V, otherwise
they are driven to VCC.
When the LTC4314 first receives power on its VCC pin, it
starts out in an undervoltage lockout mode (UVLO) until
110μs after VCC exceeds 2.3V. During this time, the buffers
and rise time accelerators are disabled, the multiplexer
gates are off and the LTC4314 ignores transitions on the
clock and data pins independent of the state of the ENABLE
pins. VCC2 transitions from a high to a low or vice-versa
across a 1.8V threshold also cause the LTC4314 to disable the buffers, rise time accelerators and transmission
gates and to ignore the clock and data pins until 110μs
after that transition. Assuming that the LTC4314 is not
in UVLO mode, when one or more ENABLEs is asserted,
the LTC4314 activates the connection circuitry between
the SDAIN, SCLIN inputs and selected output channels.
The input rise time accelerators and the output rise time
accelerators of the selected channels are also enabled at
this time. When a SDA,SCL input pin or output pin on an
enabled output channel is driven below the VIL,FALLING
level of 0.33•VMIN, the buffers are turned on and the logic
low level is propagated though the LTC4314 to the other
side. For VCC2 > 1.8V, VMIN is the lower of the VCC and
VCC2 voltages. For VCC2 < 1.8V, VMIN is the VCC voltage.
The LTC4314 is designed to sink a minimum total bus
current IOL of 4mA while holding a VOL of 0.4V. If multiple
output channels are enabled, the bus current of all enabled
channels needs to be summed to get the total bus current.
See the Typical Performance Characteristics curves for IOL
as a function of temperature.
A high occurs when all devices on the input and output
sides release high. Once the bus voltages rise above the
VIL, RISING level, which is determined by the state of the ACC
pin, the buffers are turned off. The rise time accelerators
are turned on at a slightly higher voltage. The rise time
accelerators accelerate the rising edges of the SDA,SCL
inputs and selected outputs up to voltages of 0.9•VCC and
0.8•VCC2 respectively, provided that the busses on their
own are rising at a minimum rate of 0.2V/μs as determined
by the slew rate detectors. ACC is a 3-state input that controls VIL,RISING, the rise time accelerator turn-on voltage
and the rise time accelerator pull-up strength.
The LTC4314 detects a bus stuck low (fault) condition
when both clock and data busses are not simultaneously
high at least once in 45ms. The voltage monitoring for a
stuck low condition is done on the common internal node
of the clock and data outputs. Hence a stuck low condition
is detected only if it occurs on an enabled output channel.
When a stuck bus occurs, the LTC4314 asserts the FAULT
flag. If DISCEN is tied high, the LTC4314 also disconnects
the input and output sides. After waiting at least 40μs, it
generates up to sixteen 5.5kHz clock pulses on the enabled
SCLOUT pins and a stop bit to attempt to free the stuck
bus. If the bus recovers high before 16 clocks are issued,
the LTC4314 ceases issuing clocks and generates a stop
bit. If DISCEN is tied low, a stuck bus event only causes
FAULT flag assertion. Disconnection of the input and output
sides and clock generation do not occur. Once the stuck
bus recovers and the fault has been cleared, in order for a
connection to be established between the input and output
sides, all ENABLE pins need to be driven low followed
by the assertion high of the desired ENABLE pins. When
powering into a stuck low condition, the LTC4314 upon
exiting UVLO will connect the input and output sides for
45ms until a stuck bus timeout event is detected.
4314f
8
LTC4314
APPLICATIONS INFORMATION
The LTC4314 is a 1:4 pin selectable I2C multiplexer that
provides a high noise margin, capacitance buffering and
level translation capability on its clock and data pins. Rise
time accelerators accelerate rising edges to enable operation at high frequencies with heavy loads. These features
are illustrated in the following subsections.
Rise Time Accelerators and DC Hold-Off Voltage
Once the LTC4314 has exited UVLO and a connection has
been established between the SDA and SCL inputs and
outputs, the rise time accelerators on both the input and
output sides of the SDA and SCL busses are activated based
on the state of the ACC pin and the VCC2 supply voltage.
During positive bus transitions of at least 0.2V/μs, the
rise time accelerators provide pull-up currents to reduce
rise time. Enabling the rise time accelerators allows users
to choose larger bus pull-up resistors, reducing power
consumption and improving logic low noise margins, to
design with bus capacitances outside of the I2C specification, or switch at a higher clock frequency. The ACC pin
sets the turn-off threshold voltage for the buffers, the
turn-on voltage for the rise time accelerators, and the rise
time accelerator pull-up current strength. The ACC functionality is shown in Table 1. Set ACC open or high when a
high noise margin is required, such as when the LTC4314
is used in a system having I2C devices with VOL > 0.4V.
The ACC pin has a resistive divider between VCC and
ground to set its voltage to 0.5•VCC if left open. In the
current source accelerator mode, the LTC4314 provides
a 3mA constant current source pull-up.
Table 1. ACC Control of the Rise Time Accelerator Current IRTA
and Buffer Turn-Off Voltage VIL,RISING
ACC
IRTA
Low
Strong
0.8V
0.6V
Hi-Z
3mA
0.4•VMIN
0.33•VMIN
High
None
N/A
0.33•VMIN
VIL, RISING
In the strong mode, the LTC4314 sources pull-up current
to make the bus rise at 75V/μs (typical). The strong mode
current is therefore directly proportional to the bus capacitance. The LTC4314 is capable of sourcing a maximum of
45mA of current in the strong mode. The effect of the rise
time accelerator strength is shown in the SDA waveforms in
Figures 1 and 2 for identical bus loads for a single enabled
output channel. The rise time accelerator supplies 3mA and
10mA of pull-up current (IRTA) respectively in the current
source and strong modes for the bus conditions shown
in Figures 1 and 2. The rise time accelerator turn-on voltage is also lower in the strong mode than in the current
source mode. For identical bus loading conditions, the
busses return high faster in Figure 1 compared to Figure 2
because of both the higher IRTA and the lower turn-on voltage of the rise time accelerator. In each figure, note that the
input and output rising waveforms are nearly coincident
due to the input and output busses having nearly identical
bus current and capacitance.
CIN = COUT = 200pF
RBUS = 10kΩ
ACC = OPEN
VCC = VCC2 = 5V
SDAOUT1
0V
2V/DIV
CIN = COUT = 200pF
RBUS = 10kΩ
ACC = 0
VCC = VCC = 5V
2V/DIV
VRTA(TH)
SDAOUT1
0V
SDAIN
SDAIN
0V
0V
500ns/DIV
4314 F01
Figure 1. Bus Rising Edge for the Strong
Accelerator Mode
500ns/DIV
4314 F02
Figure 2. Bus Rising Edge for the
Current Source Accelerator Mode
4314f
9
LTC4314
APPLICATIONS INFORMATION
If VCC2 is tied low, the output side rise time accelerators
are disabled independent of the state of the ACC pin. Using
a combination of the ACC pin and the VCC2 voltage allows
the user independent control of the input and output side
rise time accelerators. The rise time accelerators are also
internally disabled during power-up and VCC2 transitions
as described in the Operation section, as well as during
automatic clocking and stop bit generation for a bus stuck
low recovery event.
If VCC2 is grounded, the multiplexer pass gates are powered
from VCC. In this case the minimum output bus supply
of the enabled channels should be greater than or equal
to VCC to prevent cross-conduction between the enabled
output channels. This is shown in Figure 4. Grounding VCC2
as shown in Figure 4 disables the output side rise time
accelerators independent of the state of the ACC pin. The
input rise time accelerators in this configuration continue
to be controlled by the ACC pin and can be enabled independently. In Figure 4, ACC is left open to obtain a high VIL
and a 3mA rise time accelerator current on the input side.
The rise time accelerators when activated pull the bus up
to 0.9•VCC on the input side of the SDA and SCL lines. On
the output side the SDAOUT and SCLOUT lines are pulled
up by the rise time accelerators to 0.8•VCC2. For VCC2
voltages approaching 2.3V, acceleration of the bus may
not be seen all the way to 0.8•VCC2 due to the threshold
voltage of the NFET pass device.
Pull-Up Resistor Value Selection
To guarantee that the rise time accelerators are activated
during a rising edge, the bus must rise on its own with
a positive slew rate of at least 0.4V/μs. To achieve this,
choose a maximum RBUS using equation 1:
Supply Voltage Considerations in Level Translation
Applications
RBUS (Ω)≤
Care must be taken to ensure that the bus supply voltages
on the input and output sides are greater than 0.9•VCC and
0.8•VCC2 respectively to ensure that the bus is not driven
above the bus supplies by the rise time accelerators. This
is usually accomplished in a level shifting application by
tying VCC to the input bus supply and VCC2 to the lowest
bus supply on the output side as shown in Figure 3.
R1
10k
0.4V/µs • CBUS
3.3V
R2
10k
VCC
SCLIN
SCLIN
SDAIN
SDAIN
VCC2
R4
10k
R5
10k
C2
0.01μF
ENABLE1
ENABLE1
SCLOUT1
SCLOUT1
ENABLE2
ENABLE2
SDAOUT1
SDAOUT1
ENABLE3
ENABLE3
3.3V
R3
10k
LTC4314
ACC
DISCEN
FAULT
• • •
ENABLE4
ENABLE4
(1)
RBUS is the bus pull-up resistor, VDD, BUS(MIN) the minimum bus pull-up supply voltage, VRTA(TH) the voltage at
which the rise time accelerator turns on, which is a function of ACC, and CBUS the equivalent bus capacitance.
3.3V
C1
0.01μF
( VDD,BUS(MIN) − VRTA(TH) )
5V
R6
10k
R7
10k
SCLOUT4
SCLOUT4
SDAOUT4
SDAOUT4
FAULT
GND
4314 F03
Figure 3. Connection of the LTC4314 in a Level Shift Application. VCC2 is
Less than or Equal to the Minimum Bus Supply Voltage on the Output Side
4314f
10
LTC4314
APPLICATIONS INFORMATION
3.3V
C1
0.01μF
R1
10k
3.3V
R2
10k
VCC2
VCC
SCLIN
SCLIN
SDAIN
SDAIN
R4
10k
R5
10k
C2
0.01μF
ENABLE1
ENABLE1
SCLOUT1
SCLOUT1
ENABLE2
ENABLE2
SDAOUT1
SDAOUT1
ENABLE3
ENABLE3
3.3V
R3
10k
LTC4314
• • •
• • •
ENABLE4
ENABLE4
5V
R6
10k
ACC
DISCEN
R7
10k
SCLOUT4
SCLOUT4
SDAOUT4
SDAOUT4
FAULT
FAULT
GND
4314 F04
Figure 4. Connection of the LTC4314 in a Level Shift Application. VCC is Less than or Equal to the Minimum
Bus Supply Voltages on the Output Side. VCC2 is Grounded to Disable Output Rise Time Accelerators
RBUS values on each output channel must also be chosen
to ensure that when all the required output channels are
enabled, the total bus current is ≤4mA. The bus current
in each output channel can be 4mA if only one channel is
enabled at any given time. The RBUS value on the input must
also be chosen to limit the bus current to be ≤4mA. The
bus current for a single bus is determined by equation 2:
IBUS (A)=
VDD,BUS − 0.4V
(2)
RBUS
Input to Output Offset Voltage and Propagation Delay
The LTC4314 introduces both an offset as well as a
propagation delay for falling edges between the input
and output. When a logic low voltage ≥ 200mV is driven
on any of the LTC4314’s data or clock pins, the LTC4314
regulates the voltage on the opposite side to a slightly
higher value. When SCLIN or SDAIN is driven to a logic
low voltage, SCLOUT or SDAOUT is driven to a slightly
higher voltage, as directed by equation 3 which uses SDA
as an example:
VSDAOUT (V) = VSDAIN + 45mV
+ (10Ω + R MUX ) •
VDD,BUS
(3)
VDD, BUS is the output bus voltage, RBUS is the output bus
pull-up resistance and RMUX is the resistance of the channel
transmission gate in the multiplexer shown in the block
diagram. The offset is affected by the VCC2 voltage and bus
current. A higher VCC2 voltage (VCC if VCC2 is grounded)
reduces RMUX leading to a lower offset. See the Typical
Performance Characteristics plots for the variation of RMUX
as a function of VCC2 and temperature. When SCLOUT or
SDAOUT is driven to a logic low voltage ≥ 200mV, SCLIN
or SDAIN is regulated to a logic low voltage, as directed
by equation 4 which uses SDA as an example:
V
VSDAIN (V)= VSDAOUT + 45mV +10Ω • DD, BUS
(4)
RBUS
The SCLOUT/SDAOUT to SCLIN/SDAIN offset is lower than
the reverse case as the multiplexer transmission gate does
not affect this offset. For driven logic low voltages <200mV,
the above equations do not apply as the saturation voltage
of the open collector output transistor results in a higher
offset. However, the offset is guaranteed to be less than
400mV for a total bus pull-up current of 4mA under all
conditions. See the Typical Performance Characteristics
curves for the buffer offset voltages as a function of the
driven logic low voltage and bus pull-up current.
R BUS
4314f
11
LTC4314
APPLICATIONS INFORMATION
turn-off voltage, signals will not be propagated across the
cascade. Also the minimum rise time accelerator (RTA)
turn-on voltage (wherever applicable) of each device in
the cascade should also be greater than the maximum
buffer turn-off voltage of all the devices in the cascade.
This condition is required to prevent contention between
one device’s buffer and another’s RTA.
The high-to-low propagation delay arises due to both the
finite response time of the buffers and their finite current
sink capability. See the Typical Performance Characteristics
curves for the propagation delay as a function of the bus
capacitance.
Cascading LTC4314 devices and other LTC Bus Buffers
Multiple LTC4314s can be cascaded or the LTC4314 can
be cascaded with other LTC bus buffers as required by the
application. An example is shown for the clock pathway
in Figure 5 where an LTC4314 is cascaded with another
LTC4314 and some select LTC bus buffers. The data path
is identical. When using such cascades, users should be
aware of the additive logic low offset voltages VOS when
determining system noise margin. If the sum of the offsets
(refer to equations 3 and 4 and to the data sheets of the
corresponding bus buffers) plus the worst-case driven
logic low voltage across the cascade exceeds the buffer
3.3V
C1
0.01μF
R1
10k
Based on this requirement, the LTC4314 can be cascaded
with the LTC4303 and LTC4307 if its RTA turn-on voltage
is set to be 0.8V (ACC low). The LTC4314 can be cascaded
with the LTC4301 and LTC4301L under all ACC settings
as these devices do not have RTAs. The LTC4314 can
be cascaded with the LTC4302, LTC4304, LTC4305 and
LTC4306 if its RTAs are set to turn on at 0.8V (ACC low)
or under all ACC settings if the RTAs on the other bus buffers are disabled. Finally two LTC4314s can be cascaded
if their ACC pins are tied to the same state, HIGH, LOW or
OPEN, or if the ACC pin of one LTC4314 is tied high and
the other is left open.
3.3V
5V
VCC2
VCC
R2
10k
R3
10k
R4
10k
R5
10k
C2
0.01μF
LTC4314
SCLIN
R6
10k
VCC2
VCC
LTC4314
SCLIN
SCLOUT2
ACC
SCLOUT1
SCLOUT1
SCLOUT3
SCLOUT4
t t t
SCLOUT1
ACC
t t t
SCLIN
SCLOUT4
SCLOUT4
GND
GND
3.3V
R7
10k
VCC
LTC4301
SCLIN
SCLOUT
SCLOUT5
GND
5V
R8
10k
VCC
LTC4303
SCLIN
SCLOUT6
SCLOUT
GND
5V
R9
10k
VCC
LTC4307
SCLIN
SCLOUT
SCLOUT7
GND
4314 F05
Figure 5. Cascading an LTC4314 with Another LTC4314 and LTC Bus Buffers. Only the SCL Pathway Is Shown for Simplicity
4314f
12
LTC4314
APPLICATIONS INFORMATION
Paralleling LTC4314 Devices
The LTC4314s can be paralleled to perform higher order
multiplexing. Figure 6 shows a 1:8 multiplexer with two
LTC4314s.
3.3V
C1
0.01μF
R1
10k
R2
10k
3.3V
VCC2
VCC
R4
10k
R5
10k
C2
0.01μF
SCLIN
I2C
DEVICE
SDAIN
ENABLE1
SCLOUT1
SCLOUT1
ENABLE2
ENABLE2
SDAOUT1
SDAOUT1
ENABLE3
ENABLE3
ENABLE4
ENABLE4
LTC4314
• • •
• • •
ENABLE1
ACC
3.3V
R3
10k
DISCEN
5V
R6
10k
R7
10k
SCLOUT4
SCLOUT4
SDAOUT4
SDAOUT4
FAULT
GND
3.3V
C3
0.01μF
3.3V
VCC2
VCC
R9
10k
R10
10k
C4
0.01μF
SCLIN
SDAIN
ENABLE1
SCLOUT1
SCLOUT5
ENABLE6
ENABLE2
SDAOUT1
SDAOUT5
ENABLE7
ENABLE3
ENABLE8
ENABLE4
LTC4314
3.3V
R8
10k
• • •
• • •
ENABLE5
5V
R11
10k
ACC
DISCEN
R12
10k
SCLOUT4
SCLOUT8
SDAOUT4
SDAOUT8
FAULT
GND
4314 F06
Figure 6. Paralleling LTC4314 Devices to Realize an 1:8 Multiplexer
4314f
13
LTC4314
APPLICATIONS INFORMATION
Radial Telecommunications
Figure 7 shows the use of the LTC4314 in a radial telecommunications application. Two shelf managers are wired to
communicate with slave I2C devices for redundancy. Each
shelf manager can have as many LTC4314s as required
depending on the number of boards in the system and
the desired radial/star configuration. The ENABLE pins of
the LTC4314s inside only one shelf manager are asserted
high at any time. For simplicity, in Figure 7 only the SDA
pathway is shown. The SCL pathway is identical.
BACKPLANE
SHMC #1
FRU #1
3.3V
3.3V
R1
10k
VCC
3.3V
VCC2
R2
10k
LTC4314 #1
SDAIN
μP
SDAOUT1
ENABLE2
SDAOUT2
ENABLE3A
ENABLE3
SDAOUT3
ENABLE4A
ENABLE4
SDAOUT4
t
ENABLE1
ENABLE2A
IPMB-B
SDA1
t
ENABLE1A
IPMB-A
SDA1
ACC
GND
t
t
t
t
t t t
3.3V
VCC
VCC2
LTC4314 #6
t
SDAIN
ENABLE1
SDAOUT1
ENABLE22A
ENABLE2
SDAOUT2
ENABLE23A
ENABLE3
SDAOUT3
ENABLE24A
ENABLE4
SDAOUT4
3.3V
R3
10k
IPMB-A
SDA24
SDA1
IPMB-B (×24)
t t t
GND
t
ACC
t
ENABLE21A
FRU #24
SDA24
SHMC #2
(IDENTICAL TO SHMC#1)
IPMB-A (×24)
SDA1
t t t
IPMB-B (×24)
IPMB-B
SDA24
SDA24
4314 F07
Figure 7. LTC4314s Configured for a Radially Connected Redundant Telecommunications Shelf Manager Application
in a 6 × 4 Arrangement. The ENABLE Pins on Only One of the Shelf Managers Are High at Any Time. Only the SDA
Path Is Shown for Simplicity
4314f
14
LTC4314
APPLICATIONS INFORMATION
and output, asserting FAULT low and generating up to
16 clock pulses at 5.5kHz on the SCLOUT node common
to the four channels. Should the stuck bus release high
during this period, clock pulsing is stopped, a stop bit is
generated and FAULT flag is cleared. In order for a connection to be established between the input and output, all
ENABLES have to be taken low followed by an assertion
of the ENABLES of the required channels. This process is
illustrated in Figure 9 for the case where only channel 1 is
active and SDAOUT1 starts out stuck low and then recovers. If DISCEN is tied low and a stuck low event occurs,
the FAULT flag is driven low, but the connection between
the input and output is not broken and clock generation
is not done.
Nested Addressing
The LTC4314 can provide nested addressing when its
ENABLE pins are used as channel select bits. This is shown
in Figure 8 where the master communicates with slave
devices that have the same address by selectively enabling
only one output channel at a time. Since slaves have the
same address care must be taken that the master never
enables channels 1 and 4 at the same time.
Stop Bit Generation and FAULT Clocking
If the output bus sticks low (SCLOUT or SDAOUT stuck
low for at least 45ms) on one of the enabled channels
and DISCEN is high, the LTC4314 attempts to unstick the
bus by first breaking the connection between the input
3.3V
C1
0.01μF
R1
10k
3.3V
R2
10k
R4
10k
VCC2
VCC
R5
10k
C2
0.01μF
SCLIN
I2C
DEVICE
SDAIN
ENABLE1
ENABLE1
SCLOUT1
ENABLE2
ENABLE2
SDAOUT1
ENABLE3
ENABLE3
ENABLE4
ENABLE4
ADDRESS = 1001 000
• • •
LTC4314
• • •
3.3V
I2C
DEVICE
ACC
R3
10k
5V
R6
10k
R7
10k
SCLOUT4
I2C
DEVICE
SDAOUT4
DISCEN
FAULT
FAULT
ADDRESS = 1001 000
GND
4314 F08
Figure 8. Nested Addressing
ENABLE1
5V/DIV
DISCONNECT
AT TIMEOUT
CONNECT AT RISING EDGE OF ENABLE1
SDAIN
5V/DIV
SDAOUT1
5V/DIV
STUCK LOW>45ms
RECOVERS
DRIVEN LOW
AUTOMATIC CLOCKING
SCLOUT1
5V/DIV
1ms/DIV
4314 F09
Figure 9. Bus Waveforms During a SDAOUT1
Stuck Low and Recovery Event
4314f
15
LTC4314
APPLICATIONS INFORMATION
Demultiplexer Function
Due to its bi-directional nature, the LTC4314 can be used
as a demultiplexer. This is shown in Figure 10 where two
channels are used to drive I2C data from the master side
with redundancy to the slave side. In this application the
SDAOUT/SCLOUT channels serve as the inputs while the
SDAIN/SCLIN channel is the output. Redundancy on the
master side provides protection against power supply
failure. In Figure 10, if the 5V bus supply on channel 1
falls below 1.4V, channel 1 gets disabled as ENABLE1 is
driven below its digital threshold. Simultaneously, the VBE
of the pull-down device on ENABLE4 falls below 0.7V and
it turns off. This causes ENABLE4 to be pulled up by R7
which in turn enables channel 4, causing control to be
transferred to the backup I2C master device.
Hot-Swapping
Figure 11 shows the LTC4314 in a typical hot-swapping
application where the LTC4314 is on the backplane and I/O
cards plug into the downstream channels. The outputs must
idle high and the corresponding output channel must be
disabled before an I/O card can be plugged or unplugged
from an output channel. Figure 11 also shows the use of
a non-compliant I2C device with the LTC4314. The high
noise margin of the LTC4314 supports logic low levels up
to 0.3 • VCC, allowing devices to drive greater than 0.4V
logic low levels on the block and data lines.
Level Translating to Bus Voltages < 2.25V
The LTC4314 can be used for level translation to bus voltages below 2.25V if certain conditions are met. In order to
perform this level translation, RTAs on the low voltage side
need to be disabled in order to prevent an over drive of
the low voltage bus. This can be accomplished by forcing
ACC high or grounding VCC2. If one of the output channels is pulled up to the low voltage bus supply, all other
output channels need to be disabled when this channel
is active, in order to prevent cross conduction between
the output channels. Since the buffer turn-on and turn-off
voltages are 0.3•VMIN, the minimum bus supply voltage
is determined by equation 5:
VDD,BUS(MIN) ≥
0.3 • VMIN
(5)
0.7
in order to meet the VIH = 0.7 •VDD,BUS requirement and
not impact the high side noise margin. Users willing to live
with a lower logic high noise margin can level translate
down to 1.5V. An example of voltage level translation from
5V
3.3V
R1
10k
R2
10k
LTC4314
SDAOUT1
SCLOUT1
ENABLE1
PRIMARY
I2C
MASTER
CONTROLLER
CARD
3.3V
R3
10k
R4
10k
R5
100k
SDAOUT2
SCLOUT2
ENABLE2
R7
20k
BACKUP
I2C
MASTER
CONTROLLER
CARD
VCC
VCC2
R8
10k
R9
10k
R10
10k
SDAIN
SCLIN
C1
0.01μF
SDA
SCL
ACC
DISCEN
SDAOUT3
SCLOUT3
ENABLE3
FAULT
FAULT
SDAOUT4
SCLOUT4
ENABLE4
BFP405F
R6
50k
GND
4314 F10
Figure 10. The LTC4314 Configured as a 2:1 Demultiplexer in a System with Redundancy
4314f
16
LTC4314
APPLICATIONS INFORMATION
3.3V to 1.8V is illustrated in Figure 12, where a 3.3V input
voltage level is translated to a 1.8V output voltage level on
channel 1. Tying VCC to 3.3V satisfies equation 5. Grounding
VCC2 disables the RTA on the low voltage channel. VMIN
defaults to VCC under these conditions, making the buffer turn off voltage 0.99V. Channels 2-4 must be disabled
when channel 1 is enabled. A similar voltage translation
can also be performed going from a 3.3V bus supply on
the output side to a 1.8V bus supply on the input side if
ACC is tied high to disable the input RTA and if VCC and
VCC2 are tied to the output side bus supply.
3.3V
C1
0.01μF
I2C
DEVICE
VOL = 0.6V
R1
10k
3.3V
R2
10k
R4
10k
VCC2
VCC
R5
10k
C2
0.01μF
SCLIN
SDAIN
ENABLE1
ENABLE1
SCLOUT1
ENABLE2
ENABLE2
SDAOUT1
ENABLE3
ENABLE3
ENABLE4
ENABLE4
IO CARD
LTC4314
5V
R6
10k
ACC
R3
10k
t t t
t t t
t t t
3.3V
I2C
DEVICE
R7
10k
I2C
DEVICE
SCLOUT4
DISCEN
FAULT
CONNECTOR
SDAOUT4
FAULT
IO CARD
GND
CONNECTOR
4314 F11
Figure 11. SDA, SCL Hot Swap™ and Operation with a Non-Compliant I2C Device
3.3V
C1
0.01μF
R1
10k
R2
10k
1.8V
VCC2
VCC
SCLIN
SCLIN
SDAIN
SDAIN
R4
10k
R5
10k
C2
0.01μF
ENABLE1
SCLOUT1
SCLOUT1
ENABLE2
ENABLE2
SDAOUT1
SDAOUT1
ENABLE3
ENABLE3
ENABLE4
ENABLE4
3.3V
R3
10k
LTC4314
ACC
DISCEN
FAULT
• • •
• • •
ENABLE1
5V
R6
10k
R7
10k
C3
0.01μF
SCLOUT4
SCLOUT4
SDAOUT4
SDAOUT4
FAULT
GND
4314 F12
Figure 12. Level Shifting Down to 1.8V Using the LTC4314. VCC2 Is Grounded to Disable the Rise Time Accelerator
on the Low Voltage Bus. ENABLE2-4 Must Be Low Whenever ENABLE1 Is High
4314f
17
LTC4314
PACKAGE DESCRIPTION
GN Package
20-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.337 – .344*
(8.560 – 8.738)
.045 p.005
20 19 18 17 16 15 14 13 12
.254 MIN
.150 – .165
.0165 p.0015
11
.229 – .244
(5.817 – 6.198)
.058
(1.473)
REF
.150 – .157**
(3.810 – 3.988)
.0250 BSC
1
RECOMMENDED SOLDER PAD LAYOUT
.015 p .004
s 45o
(0.38 p 0.10)
.0075 – .0098
(0.19 – 0.25)
2 3
4
5 6
7
8
.0532 – .0688
(1.35 – 1.75)
9 10
.004 – .0098
(0.102 – 0.249)
0o – 8o TYP
.016 – .050
(0.406 – 1.270)
NOTE:
1. CONTROLLING DIMENSION: INCHES
INCHES
2. DIMENSIONS ARE IN
(MILLIMETERS)
.008 – .012
(0.203 – 0.305)
TYP
3. DRAWING NOT TO SCALE
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
.0250
(0.635)
BSC
GN20 (SSOP) 0204
4314f
18
LTC4314
PACKAGE DESCRIPTION
UDC Package
20-Lead Plastic QFN (3mm × 4mm)
(Reference LTC DWG # 05-08-1742 Rev Ø)
0.70 p0.05
3.50 p 0.05
2.10 p 0.05
1.50 REF
2.65 p 0.05
1.65 p 0.05
PACKAGE OUTLINE
0.25 p0.05
0.50 BSC
2.50 REF
3.10 p 0.05
4.50 p 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
0.75 p 0.05
3.00 p 0.10
1.50 REF
19
R = 0.05 TYP
PIN 1 NOTCH
R = 0.20 OR 0.25
s 45o CHAMFER
20
0.40 p 0.10
1
PIN 1
TOP MARK
(NOTE 6)
2
2.65 p 0.10
4.00 p 0.10
2.50 REF
1.65 p 0.10
(UDC20) QFN 1106 REV Ø
0.200 REF
0.00 – 0.05
R = 0.115
TYP
0.25 p 0.05
0.50 BSC
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
4314f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LTC4314
TYPICAL APPLICATION
1:8 Multiplexer with Level Translation and Operation with a Non-Compliant I2C Device
3.3V
C1
0.01μF
R1
10k
R2
10k
3.3V
VCC2
VCC
3.3V
R4
10k
R5
10k
C2
0.01μF
C3
0.01μF
SCLIN
I2C
DEVICE
3.3V
VCC2
VCC
R9
10k
C4
0.01μF
R10
10k
SCLIN
SDAIN
SDAIN
SCLOUT1
SCLOUT1
ENABLE5
ENABLE1
SCLOUT1
SCLOUT5
ENABLE2
ENABLE2
SDAOUT1
SDAOUT1
ENABLE6
ENABLE2
SDAOUT1
SDAOUT5
ENABLE3
ENABLE3
ENABLE7
ENABLE3
ENABLE4
ENABLE4
ENABLE8
ENABLE4
LTC4314
3.3V
R6
10k
ACC
R3
10k
5V
DISCEN
LTC4314
3.3V
R7
10k
t t t
t t t
ENABLE1
t t t
t t t
ENABLE1
R11
10k
ACC
SCLOUT4
SCLOUT4
SDAOUT4
SDAOUT4
FAULT
R8
10k
5V
DISCEN
R12
10k
SCLOUT4
SCLOUT8
SDAOUT4
SDAOUT8
FAULT
GND
GND
4314 TA02
NON-COMPLIANT
I2C DEVICE
VOL = 0.6V
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC4300A-1/
LTC4300A-2/
LTC4300A-3
LTC4302-1/
LTC4302-2
LTC4303
LTC4304
LTC4305
LTC4306
LTC4307
Hot-Swappable 2-Wire Bus Buffers
-1: Bus Buffer with READY and ENABLE
-2: Dual Supply Buffer with ACC
-3: Dual Supply Buffer with ENABLE
Address Expansion, GPIO, Software Controlled
LTC4307-1
LTC4308
LTC4309
LTC4311
LTC4310-1/
LTC4310-2
LTC4312
Addressable 2-Wire Bus Buffer
Hot-Swappable 2-Wire Bus Buffer with Stuck Bus
Recovery
2- or 4-Channel, 2-Wire Bus Multiplexers with
Capacitance Buffering
Low Offset Hot-Swappable 2-Wire Bus Buffer with
Stuck Bus Recovery
High Definition Multimedia Interface (HDMI) Level
Shifting 2-Wire Bus Buffer
Low Voltage, Level Shifting Hot-Swappable 2-Wire
Bus Buffer with Stuck Bus Recovery
Low Offset Hot-Swappable 2-Wire Bus Buffer with
Stuck Bus Recovery
Low Voltage I2C/SMBus Accelerator
Hot-Swappable I2C Isolators
Pin-Selectable, 2-Channel, 2-Wire Multiplexer with
Bus Buffer
Provides Automatic Clocking to Free Stuck I2C Busses
2 or 4 Software Selectable Downstream Busses, Stuck Bus Disconnect,
Rise Time Accelerators, Fault Reporting, ±5kV HBM ESD Tolerance
60mV Bus Offset, 30ms Stuck Bus Disconnect and Recovery, Rise Time
Accelerators, ±5kV HBM ESD Tolerance
60mV Buffer Offset, 3.3V to 5V Level Shifting, ±5kV HBM ESD Tolerance
Bus Buffer with 1V Pre-Charge, ENABLE and READY,
Level Translation to 1V Busses, Output Side Rise Time Accelerators
60mV Buffer Offset, 30ms Stuck Bus Disconnect and Recovery, Rise Time
Accelerators, ±5kV HBM ESD Tolerance
Rise Time Acceleration with ENABLE and ±8kV HBM ESD Tolerance
LTC4310-1: 100kHz Bus
LTC4310-2: 400kHz Bus
2 Pin-Selectable Downstream Busses, Stuck Bus Disconnect and Recovery,
Selectable Rise Time Accelerator Current and Activation Voltage,
±4kV HBM ESD Tolerance
4314f
20 Linear Technology Corporation
LT 1210 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2010