G784 Datasheet, PDF (1/1 Pages) Global Mixed-mode Technology Inc – ±1°C Remote and Local Temperature Sensor with SMBus Serial Interface

Global Mixed-mode Technology Inc.
G784
±1°C Remote and Local Temperature Sensor with
SMBus Serial Interface
Features
„ 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” sec-
tion)
„ SMBus Inputs with Built-in MOS Switch to Pre-
vent Reverse Current from Bus to IC VCC
Applications
Desktop and Notebook
Computers
Smart Battery Packs
LAN Servers
Industrial Controllers
Central Office
Telecom Equipment
Test and Measurement
Multi-Chip Modules
General Description
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 tran-
sistor typically a low-cost, easily mounted 2N3904 NPN
type that replace conventional thermistors or thermo-
couples. 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 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 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.
Pin Configuration
Typical Application Circuit
VCC 1
DXP ²
DXN 3
THERM 4
G784/G784-1
8
7
6
5
SMBCLK
VCC
SMBDATA _DXP
ALERT ^DXN
THERM
GND
G784/G784-1
1
8 SMBCLK
2
Thermal
7 SMBDATA
3
Pad
6 ALERT
4
5 GND
SOP-8/MSOP-8
TDFN3X3-8
Note: Recommend connecting the Thermal Pad to the GND or let it keep floating.
2N3904
0.1µF
3V TO 5.5V
VCC
DXP
SMBCLK
SMBDATA
DXN
2200pF
ALERT
THERM
GND
10kΩ EACH
CLOCK
DATA
INTERRUPT TO µC
Ver: 0.2
Oct 02, 2008
TEL: [phone]
http://www.gmt.com.tw
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