G7931/G7932 Global Mixed-mode Technology Inc. Two Remote and One Local Temperature Sensors and 3/4 Fan Controllers with SMBus Interface Features General Description The G7931/G7932 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 Optional Internal Clock Accuracy ±3% from 20°C to 80°C at 5V VCC 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 G7931/G7932 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 70h 72h for write and 7173hh for read for G7932.For G7931, ADD0 pin selects 3 different SMBus addresses. (see “ SMBus Digital Interface” section) G7931/G7932 contains 3/4 fan controllers which perform closed-loop and open-loop control. G7931/ G7932 determines the current fan speed based on the FG inputs and an externally supplied 32.768kHz clock. The driving ability is 5mA. G7931/G7932 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) G7931D51U G7932D51U G7931 G7932 -55°C to +125°C -55°C to +125°C TSSOP-20 TSSOP-20 Note: D5: TSSOP-20 1: Bonding Code 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 G7931 G7932 FAN2 1 20 FAN3 FAN2 1 20 FAN3 FG2 2 19 FG3 2 19 FG3 FAN1 FG1 3 18 NC FG2 FAN1 3 18 FAN4 4 ADD0 FG1 4 17 GND 5 16 FG4 GND 6 15 VCC 7 SCL SDA X2 ALERT NC DXP1 5 17 16 6 15 VCC ALERT NC 7 14 SCL DXP1 SGND1 8 13 SDA SGND1 8 14 13 DXP2 9 12 X2 DXP2 9 12 SGND2 10 11 X1/CLK SGND2 10 TSSOP-20 11 X1/CLK TSSOP-20 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.3 Oct 18, 2010 1