G781 Datasheet, PDF (1/14 Pages) List of Unclassifed Manufacturers – ±1°C Remote and Local Temperature Sensor with SMBus Serial Interface

Global Mixed-mode Technology Inc.
G781
±1°C Remote and Local Temperature Sensor with
SMBus Serial Interface
Features
„Two Channels: Measures Both Remote and
Local Temperatures
„No Calibration Required
„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 SO Package
Applications
Desktop and Notebook
Computers
Smart Battery Packs
LAN Servers
Industrial Controllers
Central Office
Telecom Equipment
Test and Measurement
Multi-Chip Modules
Pin Configuration
General Description
The G781 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 cali-
bration needed. The remote channel can also meas-
ure the die temperature of other ICs, such as micro-
processors, 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 cor-
responding 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.
The G781 is available in a small, 8-pin SOP sur-
face-mount package.
Ordering Information
PART*
G781
TEMP. RANGE
-20°C to +120°C
PIN-PACKAGE
8-SOP
Typical Operating Circuit
VCC 1
G781
8 SMBCLK
DXP ²
7 SMBDATA
DXN 3
6 ALERT
THERM 4
5 GND
8 Pin SOP
2N3904
0.1µF
3V TO 5.5V
VCC
DXP
SMBCLK
SMBDATA
2200pF
DXN
ALERT
THERM
GND
10kΩ EACH
CLOCK
DATA
INTERRUPT TO µC
Ver: 1.0
Oct 02, 2002
TEL: [phone]
http://www.gmt.com.tw
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