LTC1694 2 SMBus/I C Accelerator* FEATURES DESCRIPTIO n Improves SMBus Rise Time Transition The LT C 1694 is a dual SMBus active pull-up designed to n 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 TM n 2 Improves Low State Noise Margin compatible with the Philips I C Bus. n Auto Detect Low Power Standby Mode The LTC1694 allows multiple device connections or a n Wide Supply Voltage Range: 2.7V to 6V longer, more capacitive interconnect, without compro- TM n Low Profile (1mm) SOT-23 (ThinSOT ) 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 n Notebook and Palmtop Computers sources provide 2.2mA to quickly slew the SMBus line. n Portable Instruments During negative transitions or steady DC levels, the cur- n Battery Chargers rent sources decrease to 275m A to improve negative slew n Industrial Control Application rate and improve low state noise margins. An auto detect n TV/Video Products standby mode reduces supply current if both SCL and n 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. 2 I C is a trademark of Philips Electronics N.V. *U.S. Patent No. 6,650,174 TYPICAL APPLICATIO Comparison of SMBus Waveforms for V CC the LTC1694 vs Resistor Pull-Up 5V V SMBus1 CC C1 LTC1694 0.1F GND SMBus2 LTC1694 SCL SMBus SDA 1V/DIV R PULL-UP = 15.8k CLK DATA CLK DATA IN IN IN IN CLK DATA CLK DATA OUT OUT OUT OUT V = 5V 1m s/DIV CC DEVICE 1 DEVICE N C = 200pF LD f = 100kHz 1694 TA02 SMBus 1694 TA01 1694fa 1 U ULTC1694 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART Supply Voltage (V ) ................................................. 7V CC TOP VIEW NUMBER SMBus1, SMBus2 Inputs ............ 0.3V to (V + 0.3V) CC V 1 5 SMBus1 CC Operating Ambient Temperature Range LTC1694CS5 GND 2 LTC1694C ............................................... 0 C to 70 C LTC1694IS5 NC 3 4 SMBus2 LTC1694I............................................ 40 C to 85 C S5 PART MARKING S5 PACKAGE Junction Temperature........................................... 125 C 5-LEAD PLASTIC TSOT-23 Storage Temperature Range ................. 65 C to 150 C T = 125 C, q = 256 C/ W LTEE JMAX JA Lead Temperature (Soldering, 10 sec).................. 300 C LTA8 Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications that apply over the full operating temperature range, otherwise specifications are at T = 25 C. A V = 2.7V to 6V unless otherwise noted. CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Supply Voltage Range 2.7 6 V CC I Supply Current SMBus1 = SMBus2 = Open l 20 60 100 m A CC I Pull-Up Current SMBus1 = SMBus2 = 0V l 125 275 350 m A PULL-UP Boosted Pull-Up Current Positive Transition on SMBus ( Figure 1) l 1.0 2.2 mA Slew Rate = 0.5V/m s, SMBus > V THRES V Input Threshold Voltage Slew Rate = 0.5V/m s (Figure 1) l 0.4 0.65 0.9 V THRES SR Slew Rate Detector Threshold SMBus > V l 0.2 0.5 V/m s THRES THRES t SMBus Rise Time Bus Capacitance = 200pF (Note 2) l 0.32 1.0 m s r 2 Standard Mode I C Bus Rise Time Bus Capacitance = 400pF (Note 3) l 0.30 1.0 m s f SMBus Maximum Operating Frequency (Note 4) l 100 kHz MAX 2 Note 1: Absolute Maximum Ratings are those values beyond which the life Note 3: The rise time of an I C bus line is calculated from V to IL(MAX) of a device may be impaired. V or 1.5V to 3V (with V = 5V). This parameter is guaranteed by IH(MIN) CC design and not tested. With a minimum boosted pull-up current of 1mA: Note 2: The rise time of an SMBus line is calculated from (V IL(MAX) 0.15V) to (V + 0.15V) or 0.65V to 2.25V. This parameter is Rise Time = (3V 1.5V) 400pF/1mA = 0.6m s IH(MIN) guaranteed by design and not tested. With a minimum pull-up current of Note 4: This parameter is guaranteed by design and not tested. 125m A, a minimum boosted pull-up current of 1mA and a maximum input threshold voltage of 0.9V: Rise Time = (0.9V 0.65V)/125m A + (2.25V 0.9V)/1mA 200pF = 0.67m s 1694fa 2 U WWW