Document
Global Mixed-mode Technology Inc.
G771
Two Remote Temperature Sensors with SMBus Serial Interface and System Reset Circuit
Features
Measures Two Remote Temperatures No Calibration Required SMBus 2-Wire Serial Interface Programmable Under/Over-temperature Alarms Programmable Thermal Shutdown Signal Supports SMBus Alert Response Accuracy: ±5°C (-40°C to + 125°C, remote) ±3°C (+60°C to + 100°C, remote) 4.5V to 5.5V Supply Range Precision Monitoring of 5V Power-Supply Voltage 140ms Min Power-On Reset Pulse Width RESET Output Guaranteed RESET Valid to VCC=1V Power Supply Transient Immunity No External Components needed for reset function Small, 16-Pin SSOP Package
General Description
The G771 contains a precise digital thermometer, a system-reset circuit, and a programmable thermal shutdown signal. The thermometer reports the temperature of 2 remote sensors. The remote sensors are diode-connected transistors typically a low-cost, easily mounted 2N3904 NPN type that replace conventional thermistors or thermocouples. Remote accuracy is ±5°C for multiple transistor manufacturers, with no calibration needed. 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 (SMBusTM) Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read temperature data. The data format is 7 bits plus sign, with each bit corresponding to 1°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 Central Office Computers Telecom Equipment Smart Battery Packs Test and Measurement LAN Servers Multi-Chip Modules Industrial Controls
Ordering Information
PART*
G771
TEMP. RANGE
-55°C to +125°C
PIN-PACKAGE
16SSOP
Pin Configuration
G771
NC Vcc DXP1 DXN DXP2 NC DGND AGND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 TH_SHUT(push-pull) NC SMBCLK NC SMBDATA ALERT NC RESET
16Pin SSOP
Ver 0.2 Preliminary Dec 11, 2001
TEL: 886-3-5788833 http://www.gmt.com.tw
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Global Mixed-mode Technology Inc.
The G771 also contains a microprocessor (µP) supervisory circuit used to monitor the power supplies in µP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5V-powered circuits. This circuit asserts a reset signal whenever the VCC supply voltage declines below a preset threshold, keeping it asserted for at least 140ms after VCC has risen above the reset threshold. The G771 has an active-low RESET output. The reset comparator is designed to ignore fast transients on VCC. Reset threshold of this circuit is set to 4.38V.
G771
the Tcrit1 (SMBus 35h) threshold consecutively for the times equal to the number of faults of the FQ_TH_SHUT registers, TH_SHUT pin becomes logic high. The same mechanism is duplicated for DX2. Therefore, either one of DX1, DX2 continuously over their respective Tcrit, the TH_SHUT will assert logic high to indicate a thermal shutdown event.
The G771’s SMBus device address is fixed to be 7Ah for write and 7Bh for read. The G771 is available in a small, 16-pin SSOP surface-mount package.
When the temperature of DX1 reaches or exceeds
Typical Operating Circuit
TH_SHUT
Vcc 0.1µF
Vcc
0.1µF
10k EACH
G771
DXP1 DXN 2N3904 2200pF ALERT INTERRUPT TO µC SMBCLK SMBDATA SMBCLK SMBDATA
DXP2 2N3904 2200pF
RESET
RESET
µP
GND
Ver 0.2 Preliminary Dec 11, 2001
TEL: 886-3-5788833 http://www.gmt.com.tw
2
Global Mixed-mode Technology Inc.
Absolute Maximum Ratings
Vcc to GND……………….………….…….-0.3V to +6V DXP1, DXP2 to GND……………0.3V to (Vcc + 0.3V) DXN to GND……………………………...-0.3V to +0.8V SMBCLK, SMBDATA, ALERT to GND...-0.3V to +6V SMBDATA, ALERT Current…………...-1mA to +50mA DXN Current………………………………………±1mA
G771
ESD Protection (human body model)……………..2000V Continuous Power Dissipation (T A= +70°C) SSOP (de-rate 8.30mW/°C above +70°C)………….…667mW Operating Temperature Range………-55°C to +125°C Junction Temperature……………………....+150°C Storage temperature Range…………..-65°C to +165°C Lead Temperature (soldering,10sec)………….+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Electrical Characteristics
(Vcc = + 5V, TA = 60°C, unless otherwise noted.) PARAMETER
Temperature Sensor Temperature Resolution (Note 1) Temperature Error, Rem.