G768B Datasheet, PDF (1/15 Pages) List of Unclassifed Manufacturers – Remote/Local Temperature Sensor, 2 Fan Controllers with SMBus Serial Interface and System Reset Circuit

Global Mixed-mode Technology Inc.
G768B
Remote/Local Temperature Sensor, 2 Fan Controllers
with SMBus Serial Interface and System Reset Circuit
Features
„Measures Two Remote and One Local
Temperatures
„No Calibration Required
„SMBus 2-Wire Serial Interface
„Programmable Under/Over-temperature
Alarms
„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
„Constant Fan Speed Control
„Built-in MOSFET switch
„Internal short-circuit protection
„PWM control for stable operation
„Watchdog for fan control
„Precision Monitoring of 5V Power-Supply
Voltage
„140ms Min Power-On Reset Pulse Width
RESET Output
„Guaranteed RESET Valid to V_CC=1V
„Power Supply Transient Immunity
„No External Components needed for reset
function
„Small, 16-Pin SSOP Package
Applications
„Desktop and Notebook
„Central Office Computers
„Telecom Equipment
„Smart Battery Packs
„Test and Measurement
„LAN Servers
„Multi-Chip Modules
„Industrial Controls
Pin Configuration
G768B
OUT1 1
Vcc 2
DXP1 3
DXN 4
DXP2 5
RESET 6
GND 7
GND 8
16 OUT2
15 Vcc
14 SMBCLK
13 FG2
12 SMBDATA
11 ALERT
10 FG1
9 CLK
16Pin SSOP
Ver 1.3
Oct 28, 2002
General Description
The G768B contains a precise digital thermometer, 2
fan controllers, and a system-reset circuit.
The G768B is backward compatible with G768, Except
that there is an additional watchdog function. This
function prevents fan from being out of control when
system fails.
The thermometer reports the temperature of 2 remote
sensors and its own package. 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 (SMBus^TM) 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 cor-
responding 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.
G768B also contains a 2-channel fan speed controller.
It connects directly to the fans and performs
closed-loop control of the fan speed independently.
The only external component required is a 10µF ca-
pacitor per channel. It determines the current fan
speed based on the fan rotation pulses and an exter-
nally supplied clock. (To be continued)
Ordering Information
PART*
G768B
TEMP. RANGE
-10°C to +85°C
PIN-PACKAGE
16SSOP
TEL: [phone]
http://www.gmt.com.tw
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