Linear Technology LTC1694-1 Datasheet

FEATURES

■

Improves SMBus/I2CTM Rise Time Transition

■

Ensures Data Integrity with Multiple Devices
on the SMBus/I2C

■

Improves Low State Noise Margin

■

Wide Supply Voltage Range: 2.7V to 6V

■

Tiny 5-Pin SOT-23 Package

■

Parallel Multiple LTC1694-1 Devices
for Increased Drive

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APPLICATIO S

■

Notebook and Palmtop Computers

■

Portable Instruments

■

Battery Chargers

■

Industrial Control Application

■

TV/Video Products

■

ACPI SMBus Interface

LTC1694-1

SMBus/I2C Accelerator

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DESCRIPTIO

The LTC®1694-1 is a dual SMBus active pull-up designed
to enhance data transmission speed and reliability under
all specified SMBus loading conditions. The LTC1694-1 is
also compatible with the Philips I2C Bus.

The LTC1694-1 allows multiple device connections or a
longer, more capacitive interconnect, without compro­mising slew rates or bus performance, by supplying a high
pull-up current of 2.2mA to slew the SMBus or I2C lines
during positive bus transitions

During negative transitions or steady DC levels, the
LTC1694-1 sources zero current. External resistors, one
on each bus line, trigger the LTC1694-1 during positive
bus transitions and set the pull-down current level. These
resistors determine the slew rate during negative bus
transitions and the logic low DC level.

The LTC1694-1 is available in a 5-pin SOT-23 package.

, LTC and LT are registered trademarks of Linear Technology Corporation.

I2C is a trademark of Philips Electronics N.V.

TYPICAL APPLICATIO

V

CC

5V

1

V

C1

0.1µF

2

GND

SCL

SMBus

SDA

CLK

IN

CLK

OUT

DEVICE 1

LTC1694-1: Patent Pending

DATA

DATA

CC

LTC1694-1

IN

OUT

SMBus1

SMBus2

5

4

CLK

IN

CLK

OUT

DEVICE N

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V

CC

5V

DATA

DATA

OUT

Comparison of SMBus Waveforms for

the LTC1694-1 vs Resistor Pull-Up

R

R

P2

P1

IN

1694-1 TA01

LTC1694-1

1V/DIV

VCC = 5V 1µs/DIV 1694-1 TA02
CLD = 200pF

= 100kHz

f

SMBus

R

PULL-UP

= 15.8k

1

LTC1694-1

VCC 1

GND 2

NC 3

5 SMBus1

4 SMBus2

TOP VIEW

S5 PACKAGE

5-LEAD PLASTIC SOT-23

WW

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ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage (VCC) ................................................. 7V

SMBus1, SMBus2 Inputs ............ –0.3V to (VCC + 0.3V)

Operating Ambient Temperature Range....... 0°C to 70°C

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PACKAGE/ORDER INFORMATION

ORDER PART

NUMBER

LTC1694-1CS5

Junction Temperature........................................... 125°C

Storage Temperature Range ................. –65°C to 150°C

S5 PART MARKING

Lead Temperature (Soldering, 10 sec.).................300°C

T

= 125°C, θJA = 256°C/W

JMAX

Consult factory for Industrial and Military grade parts.

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 6V, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CC

I

CC

I

PULL-UP

V

THRES

SR

THRES

t

r

f

MAX

Supply Voltage Range 2.7 6 V
Supply Current SMBus1 = SMBus2 = V
Pull-Up Current Positive Transition on SMBus ( Figure 1) ● 1.0 2.2 mA

Input Threshold Voltage Slew Rate = 0.5V/µs (Figure 1) ● 0.4 0.65 0.9 V
Slew Rate Detector Threshold SMBus > V
SMBus Rise Time Bus Capacitance = 200pF (Note 2) ● 0.32 1.0 µs

Standard Mode I
SMBus Maximum Operating Frequency (Note 4) ● 100 kHz

2

C Bus Rise Time Bus Capacitance = 400pF (Note 3) ● 0.30 1.0 µs

The ● denotes specifications which apply over the full operating

CC

Slew Rate = 0.5V/µs, SMBus > V

THRES

THRES

● 15 45 80 µA

● 0.2 0.5 V/µs

LTHE

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Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: The rise time of an SMBus line is calculated from (V

0.15V) to (V
guaranteed by design and not tested. With a minimum initial slew rate of

0.5V/µs, a minimum pull-up current of 1mA and a maximum input
threshold voltage of 0.9V:

2

–

+ 0.15V) or 0.65V to 2.25V. This parameter is

IH(MIN)

Rise Time = [(0.9V – 0.65V)/0.5V/µs] + [(2.25V – 0.9V) • 200pF/1mA]

= 0.77µs

IL(MAX)

Note 3: The rise time of an I2C bus line is calculated from V

or 1.5V to 3V (with VCC = 5V). This parameter is guaranteed by

V

IH(MIN)

design and not tested. With a minimum boosted pull-up current of 1mA:

Rise Time = (3V – 1.5V) • 400pF/1mA = 0.6µs

Note 4: This parameter is guaranteed by design and not tested.

IL(MAX)

to

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TYPICAL PERFORMANCE CHARACTERISTICS

Pull-Up Current

3.50

3.25

3.00

2.75

–50

VCC = 6V

VCC = 5V

VCC = 2.7V

0

–25

TEMPERATURE (°C)

50

25

75

100

1694-1 G01

Pull-Up Current
vs SMBus Voltage

3.5

3.0

2.5

2.0

1.5

1.0

PULL-UP CURRENT (mA)

0.5

0

0

12

SMBus VOLTAGE (V)

VCC = 6V

VCC = 5V

VCC = 2.7V

467

35

2.50

2.25

2.00

1.75

PULL-UP CURRENT (mA)

1.50

1.25

1.00

LT1694 G02

125

Input Threshold Voltage

0.90

0.85

0.80

0.75
VCC = 5V

0.70

0.65

0.60

0.55

0.50

INPUT THRESHOLD VOLTAGE (V)

0.45

0.40

–50

–25

VCC = 6V

VCC = 2.7V

0

25

TEMPERATURE (°C)

LTC1694-1

50

75

100

125

1694 G03

Slew Rate Detector Threshold

0.50

0.45

0.40

0.35

0.30

0.25

SLEW RATE DETECTOR THRESHOLD (V/µs)

0.20

0.15

0.10

0.05
0

–50

VCC = 5V

–25

VCC = 6V

VCC = 2.7V

0

TEMPERATURE (°C)

50

25

Standby Mode Supply Current

80

70

60

50

40

30

SUPPLY CURRENT (µA)

20

100

125

1694 G04

75

10

VCC = 5V

–25 25 75 125

–50

050

TEMPERATURE (°C)

VCC = 6V

VCC = 2.7V

100

1694-1 G05

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