LTC4311
Low Voltage I
2
C/SMBus
Accelerator
FEATURES
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DESCRIPTION
The LTC
®
4311 is a dual I
2
C active pull-up designed to
enhance data transmission speed and reliability for bus
loading conditions well beyond the 400pF I
2
C specification
limit. The LTC4311 operates at supply voltages from 1.6V
to 5.5V and is also compatible with SMBus.
The LTC4311 allows multiple device connections or a lon-
ger, more capacitive interconnect, without compromising
slew rates or bus performance, by using two slew limited
pull-up currents.
During positive bus transitions, the LTC4311 provides slew
limited pull-up currents to quickly slew the I
2
C or SMBus
lines to the bus pull-up voltage. During negative transitions
or steady DC levels, the currents are disabled to improve
negative slew rate, and improve low state noise margins.
An auto detect standby mode reduces supply current if
both SCL and SDA are high. When disabled, the LTC4311
goes into low (<5μA) current shutdown.
The LTC4311 is available in the 2mm
×
2mm
×
0.75mm
DFN, and SC70 packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All
other trademarks are the property of their respective owners. Protected by U.S. Patents
including 6356140 and 6650174.
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Improves I
2
C Bus Rise Time Transition
Ensures Data Integrity with Multiple Devices on the
I
2
C Bus.
Wide Supply Voltage Range: 1.6V to 5.5V
Improves Low State Noise Margin
Up to 400kHz Operation
Auto Detect Low Power Standby Mode
Low (<5μA) Supply Current Shutdown
Does Not Load Bus When Disabled or Powered Down
Strong Slew Limited Pull-up Current
±8kV Human Body Model ESD Ruggedness
2mm
×
2mm DFN and SC70 Packages
APPLICATIONS
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Notebook and Palmtop Computers
Portable Instruments
Battery Chargers
Industrial Controls
TV/Video Products
ACPI SMBus Interface
TYPICAL APPLICATION
V
CC
2.5V
V
CC
C1
0.01μF
ENABLE
GND
I
2
C
SCL
SDA
CLK
IN
CLK
OUT
DEVICE 1
DATA
IN
DATA
OUT
CLK
IN
CLK
OUT
DEVICE N
4311 TA01a
LTC4311
BUS1
V
CC
2.5V
Comparison of I
2
C Waveforms for
the LTC4311 vs Resistor Pull-Up
10k
BUS2
10k
1V/DIV
LTC4311
DATA
IN
DATA
OUT
V
CC
= 5V
C
LD
= 200pF
f
I
2
C
= 100kHz
R
PULL-UP
= 15.8k
1μs/DIV
4311 TA01b
4311fa
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LTC4311
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
V
CC
to GND .................................................... – 0.3 to 6V
BUS1, BUS2, ENABLE Inputs ......................... – 0.3 to 6V
Operating Temperature
LTC4311C ................................................ 0°C to 70°C
LTC4311I..............................................– 40°C to 85°C
Storage Temperature Range (DFN) ........– 65°C to 125°C
Storage Temperature Range (SC70).......– 65°C to 125°C
Lead Temperature (Soldering 10, sec)
SC70 ............................................................ 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
ENABLE 1
NC 2
V
CC
3
7
6 GND
5 BUS2
4 BUS1
V
CC
1
GND 2
ENABLE 3
6 BUS1
5 GND
4 BUS2
DFN PACKAGE
6-LEAD (2mm 2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 102°C/W
EXPOSED PAD (PIN 7) PCB CONNECTION TO GND IS OPTIONAL (Note 3)
SC70 PACKAGE
6-LEAD PLASTIC SC70
T
JMAX
= 125°C,
θ
JA
= 150° C/W
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI)
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
LTC4311CDC#TRMPBF
LTC4311CDC#TRPBF
LCNG
6-Lead (2mm
×
2mm) Plastic DFN
LTC4311IDC#TRMPBF
LTC4311IDC#TRPBF
LCNG
6-Lead (2mm
×
2mm) Plastic DFN
LTC4311CSC6#TRMPBF
LTC4311CSC6#TRPBF
LCNF
6-Lead (2mm
×
2mm) Plastic SC70
LTC4311ISC6#TRMPBF
LTC4311ISC6#TRPBF
LCNF
6-Lead (2mm
×
2mm) Plastic SC70
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on 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/
4311fa
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LTC4311
ELECTRICAL CHARACTERISTICS
•
SYMBOL
V
CC
I
CC
PARAMETER
Positive Supply Voltage
Supply Current
V
CC
= 5.5V, ENABLE = 5.5V, V
BUS1
= V
BUS2
= 0V
V
CC
= 5.5V, ENABLE = 5.5V, V
BUS1
= V
BUS2
= 5.5V
V
CC
= 5.5V, ENABLE = 0V, V
BUS1
= V
BUS2
= 5.5V
Positive Transition on Bus, Slew Rate = 0.5V/μs
V
CC
= 1.8V, BUS > V
THR
V
CC
= 0V, V
BUS1
= V
BUS2
= 5.5V
V
CC
= 0V, V
ENABLE
= 5.5V
V
CC
= 1.8V
V
CC
= 2.5V
V
CC
= 2.7V to 5.5V
V
THR_ENABLE
ENABLE Threshold Voltage
SR
THRESH
t
r
f
MAX
Slew Rate Detector Threshold
Fast Mode I
2
C Bus Rise Time
Bus Maximum Operating Frequency
V
CC
= 1.6V, 5.5V
BUS > V
THR
, V
CC
= 1.8V, 5.5V
Bus Capacitance = 400pF V
CC
= 3V (Note 4)
,
(Note 5)
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.3V, unless otherwise noted.
CONDITIONS
●
●
●
●
●
●
●
●
●
●
●
●
●
●
MIN
1.6
TYP
200
26
MAX
5.5
300
45
±5
UNITS
V
μA
μA
μA
mA
I
CC_STANDBY
Supply Current, Standby Mode
I
CC_DISABLED
Supply Current, Disabled
I
PULLUPAC
I
BUS(IN)
I
ENABLE(IN)
V
THR
Transient Boosted Pull-up Current
BUS1,BUS2, Input Leakage Current
ENABLE Input Leakage Current
Bus Input Threshold Voltage
2.5
5
±5
±10
μA
μA
V
V
V
V
V/μs
ns
kHz
0.45
0.65
0.68
0.4
0.55
0.75
0.78
1
0.2
0.65
0.85
0.88
1.5
0.5
300
400
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. All voltages are referenced to
GND unless otherwise specified.
Note 3:
Thermal characteristics are determined with exposed pad soldered
to GND plane. If the exposed pad is left open, thermal characteristics can
be drastically different.
Note 4:
The rise time of an I
2
C bus line is calculated from V
IL(MAX)
to
V
IH(MIN)
or 0.9V to 2.1V (with V
CC
= 3V). This parameter is guaranteed by
design and not tested. With a minimum boosted pull-up current of 2.5mA:
Rise Time = (2.1V – 0.9V) • 400pF/2.5mA = 0.19μs.
Note 5:
Determined by design, not tested in production.
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LTC4311
TYPICAL PERFORMANCE CHARACTERISTICS
Boost Pull-Up Current vs
Temperature
40
BOOST PULL-UP CURRENT (mA)
BOOST PULL-UP CURRENT (mA)
35
30
25
20
15
10
5
V
CC
= 3.3V
V
CC
= 2.5V
V
CC
= 1.8V
0
60
40
20
TEMPERATURE (°C)
80
100
4311 G01
(T
A
= 25°C, unless otherwise indicated)
Boost Pull-Up Current vs Bus
Capacitance
60
R
p
= 2kΩ
V
CC
= 5.5V
50
40
30
V
CC
= 3.3V
20
V
CC
= 2.5V
10
V
CC
= 1.8V
0
0
1000
2000
3000
4000
CAPACITANCE (pF)
5000
4311 G02
R
P
= 4.7kΩ
C
BUS
= 1nF
V
CC
= 5.5V
0
–40 –20
Supply Current vs Temperature
210
200
SUPPLY CURRENT (μA)
190
180
170
160
150
140
V
CC
= 1.8V
0
60
40
20
TEMPERATURE (°C)
80
100
4311 G03
Rise Time vs Capacitance
300
V
CC
= 1.8V
250
V
CC
= 3.3V
RISE TIME (
ns
)
V
CC
= 2.5V
V
CC
= 5.5V
V
CC
= 3.3V
BUS1 = BUS2 = 0V
200
150
V
CC
= 5.5V
100
50
0
0
1000
2000
3000
4000
CAPACITANCE (pF)
5000
4311 G04
V
CC
= 2.5V
R
P
= 2kΩ
Measured from 0.3 • V
CC
to 0.7 • V
CC
130
–40 –20
Standby Current vs Temperature
30
28
STANDBY CURRENT (μA)
26
24
22
20
18
V
CC
= 1.8V
16
–40 –20
40
20
60
0
TEMPERATURE (°C)
80
100
4311 G05
Bus Input Threshold Voltage vs
Supply Voltage
0.8
0.75
V
CC
= 5.5V
INPUT THRESHOLD (V)
V
CC
= 2.5V
0.7
0.65
0.6
0.55
0.5
0.45
0.4
1
2
4
SUPPLY VOLTAGE (V)
3
5
6
4311 G06
V
CC
= 3.3V
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LTC4311
PIN FUNCTIONS
BUS1:
Active Pull-up for Bus. Connect to either clock line
or data line for 2-wire bus.
BUS2:
Active Pull-up for Bus. Connect to either clock line
or data line for 2-wire bus.
ENABLE:
Device Enable Input. This is a 1V nominal digital
threshold input pin. For normal operation drive ENABLE
to a voltage greater than 1.5V. Driving ENABLE below the
0.4V threshold puts the device in a low (<5μA) current
shutdown mode and puts the BUS pins in a high imped-
ance state. If unused, connect to V
CC
.
EXPOSED PAD (DFN Package Only):
Exposed Pad may
be left open or connected to device ground.
GND:
Device Ground. Connect this pin to a ground plane
for best results.
V
CC
:
Supply Voltage Input. Connect this pin to bus supply
and place a bypass capacitor of at least 0.01μF close to
V
CC
for best results.
BLOCK DIAGRAM
5mA
BUS1
SLEW RATE
DETECTOR
V
CC
5mA
BUS2
SLEW RATE
DETECTOR
+
V
THR
–
+
CONTROL
LOGIC AND
INTERNAL SLEW
COMPARATOR
V
THR
–
+
V
CC
– 0.4
–
+
V
CC
– 0.4
–
+
1V
GND
ENABLE
–
4311 BD
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