G784 Global Mixed-mode Technology Inc. ±1°C Remote and Local Temperature Sensor with SMBus Serial Interface Features General Description Two Channels: Measures Both Remote and Local Temperatures No Calibration Required Built-in Noise-Buster for Remote Sensor SMBus 2-Wire Serial Interface Programmable Under/Overtemperature Alarms Supports SMBus Alert Response Accuracy: ±1°C (+60°C to +100°C, remote) ±3°C (+60°C to + 100°C, local) 320µA (typ) Average Supply Current During Conversion +3V to +5.5V Supply Range Small 8-Lead SOP , MSOP and TDFN Package Remote Temperature Measurment up to 160°C by using offset shifting method (see “Measure Remote Temperature Higher Than 127°C” section) SMBus Inputs with Built-in MOS Switch to Prevent Reverse Current from Bus to IC VCC The G784 is a precise digital thermometer that reports the temperature of both a remote sensor and its own package. The remote sensor is a diode-connected transistor typically a low-cost, easily mounted 2N3904 NPN type that replace conventional thermistors or thermocouples. Remote accuracy is ±1°C with no calibration needed. It also has a build-in noise filtering function in remote sensor measuring the diode temperature. The remote channel can also measure the die temperature of other ICs, such as microprocessors, that contain an on-chip, diode-connected transistor. The 2-wire serial interface accepts standard System Management Bus (SMBus) Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read temperature data. The data format is 11bits plus sign, with each bit corresponding to 0.125°C, in two’s-complement format. Measurements can be done automatically and autonomously, with the conversion rate programmed by the user or programmed to operate in a single-shot mode. The adjustable rate allows the user to control the supply current drain. Applications Desktop and Notebook Computers Smart Battery Packs LAN Servers Industrial Controllers The G784 and G784-1 have the same functions but different SMBus slave addresses. This allows for one of each to be on the bus at the same time. The G784 is available in a small, 8-pin SOP, MSOP and TDFN surface-mount package. Central Office Telecom Equipment Test and Measurement Multi-Chip Modules Pin Configuration Typical Application Circuit 3V TO 5.5V 0.1µF G784/G784-1 VCC DXP G784/G784-1 8 1 7 2 VCC SMBCLK SMBDATA DXN 3 6 ALERT THERM 4 5 GND VCC 1 DXP 2 DXN THERM SOP-8/MSOP-8 3 Thermal Pad 8 SMBCLK 7 SMBDATA 6 5 4 DXP 10kΩ EACH SMBCLK SMBDATA ALERT DXN GND 2N3904 ALERT CLOCK DATA INTERRUPT TO µC 2200pF THERM GND TDFN3X3-8 Note: Recommend connecting the Thermal Pad to the GND or let it keep floating. Ver: 0.2 Oct 02, 2008 TEL: 886-3-5788833 http://www.gmt.com.tw 1