G793/G794 Global Mixed-mode Technology Inc. Two Remote and One Local Temperature Sensors and 3/4 Fan Controllers with SMBus Interface Features General Description The G793/G794 contains 3 precise digital thermometers, 3/4 fan controllers, fan failure detection. Measures Two Remote and One Local Temperatures Adjustable Offset for Each Sensor via SMBus Accuracy: Remote ±1°C (+20°C to +80°C) ±3°C (-10°C to +120°C) +4.5V to +5.5V Supply Range Alert Signal for Diode Fault, Fan Fail, and Fan Out of Control Supports SMBus Alert Response Fan Drivers Using Linear Control Algorithm Closed Loop Speed Control and programmable 8 Bits Open Loop Voltage Control for Fan Wide speed control range for Fan, Accuracy within 2%, when FANx_SET_CNT > 50 Internal Current-limit and Over-temperature Protection for the Fan Controllers Build-In Inverters for Driving Crystal 20-Pin TSSOP Package The thermometers report the temperature of 2 remote sensors and 1 local sensor. The remote sensors are diode-connected transistors typically a low-cost, easily mounted 2N3904 NPN type or the diode built-in in CPU. Remote accuracy is ±1°C for multiple transistor manufacturer. Local accuracy is ±3°C. The G793/G794 also support offset adjust function via SMBus to fix the error due to different CPU diode or parasitic resistors. The 2-wire serial interface accepts standard System Management Bus (SMBusTM) Write Byte, Read Byte, Send Byte, and Receive Byte commands. The SMBus address is 72h for write and 73h for read. G793/G794 contains 3/4 controllers. FAN controller performs closed-loop and open-loop control. G793/G794 determines the current fan speed based on the FG inputs and an externally supplied 32.768kHz clock. The driving ability is 5mA. G793/G794 also provides ALERT for fan fail and out of control event. Applications Projector, LCD TV, PDP TV Desktop and Notebook Central Office Computers Telecom Equipments Industrial Controls LAN Servers SMBusTM is a trademark of Intel Corp Ordering Information ORDER NUMBER MARKING TEMP. RANGE PACKAGE (Green) G793D5U G794D5U G793 G794 -55°C to +125°C -55°C to +125°C TSSOP-20 TSSOP-20 Note: D5: TSSOP-20 U: Tape & Reel GMT Inc. does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and GMT Inc. reserves the right at any time without notice to change said circuitry and specifications. Pin Configuration G793 G794 FAN2 1 20 FAN3 FG2 2 19 FG3 FAN1 FG1 3 18 4 5 17 16 GND 6 15 DVCC 14 SCL AVCC DXP1 SGND1 7 8 13 SDA SGND1 DXP2 9 12 X2 DXP2 SGND2 10 11 X1/CLK SGND2 ALERT AVCC DXP1 FAN2 1 20 FAN3 19 FG3 NC FG2 FAN1 2 3 18 FAN4 NC FG1 4 17 ALERT 5 6 16 FG4 GND 15 DVCC 7 SCL 8 14 13 9 12 X2 10 11 X1/CLK TSSOP-20 SDA TSSOP-20 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 2.0 Oct 18, 2010 1