Datasheet LTC1694 (Analog Devices)

LTC1694 SMBus/I2C Accelerator*
U FEATURES DESCRIPTIO
■
Improves SMBus Rise Time Transition
The LT C®1694 is a dual SMBus active pull-up designed to ■
Ensures Data Integrity with Multiple Devices
enhance data transmission speed and reliability under all
on the SMBus
specified SMBus loading conditions. The LTC1694 is also ■ Improves Low State Noise Margin compatible with the Philips I2CTM Bus. ■ Auto Detect Low Power Standby Mode The LTC1694 allows multiple device connections or a ■ Wide Supply Voltage Range: 2.7V to 6V longer, more capacitive interconnect, without compro- ■ Low Profile (1mm) SOT-23 (ThinSOTTM) Package mising slew rates or bus performance, by using two
U
bilevel hysteretic current source pull-ups.
APPLICATIO S
During positive bus transitions, the LTC1694 current ■ Notebook and Palmtop Computers sources provide 2.2mA to quickly slew the SMBus line. ■ Portable Instruments During negative transitions or steady DC levels, the cur- ■ Battery Chargers rent sources decrease to 275µA to improve negative slew ■ Industrial Control Application rate and improve low state noise margins. An auto detect ■ TV/Video Products standby mode reduces supply current if both SCL and ■ ACPI SMBus Interface SDA are high. The LTC1694 is available in a 5-pin SOT-23 package, requiring virtually the same space as two surface mount resistors. , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. I2C is a trademark of Philips Electronics N.V. *U.S. Patent No. 6,650,174
U TYPICAL APPLICATIO Comparison of SMBus Waveforms for
VCC
the LTC1694 vs Resistor Pull-Up
5V VCC SMBus1 C1 LTC1694 0.1µF GND SMBus2 LTC1694 SCL SMBus SDA 1V/DIV RPULL-UP = 15.8k CLK DATA CLK DATA IN IN IN IN CLK DATA CLK DATA OUT OUT OUT OUT VCC = 5V 1µs/DIV DEVICE 1 DEVICE N CLD = 200pF f 1694 TA01 SMBus = 100kHz 1694 TA02 1694fa 1