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G768 の電気的特性と機能

G768のメーカーはETCです、この部品の機能は「Remote/Local Temperature Sensor/ 2 Fan Controllers with SMBus Serial Interface and System Reset Circuit」です。


製品の詳細 ( Datasheet PDF )

部品番号 G768
部品説明 Remote/Local Temperature Sensor/ 2 Fan Controllers with SMBus Serial Interface and System Reset Circuit
メーカ ETC
ロゴ ETC ロゴ 




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G768 Datasheet, G768 PDF,ピン配置, 機能
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 VCC=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 (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 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: 886-3-5788833
http://www.gmt.com.tw
1

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G768 pdf, ピン配列
Global Mixed-mode Technology Inc.
G768B
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
ESD Protection (SMBCLK, SMBDATA, ALERT , hu-
man body model)….…………………………….4000V
ESD Protection (other pins, human body
model).2000V
Continuous Power Dissipation (TA= +70°C) SSOP
(de-rate 8.30mW/°C above +70°C)…….………667mW
Operating Temperature Range………-10°C to +85°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 opera-
tional 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
CONDITIONS
Temperature Sensor
Temperature Resolution(Note 1)
Monotonicity guaranteed
Temperature Error, Remote Diode (Notes 2 TR = 0°C to +125°C
and 3)
TR = 60°C to +100°C
Temperature Error, Local Diode
(Notes 1 and 2)
Including long-term drift
TA = +60°C to +100°C
Supply-Voltage Range
Under-voltage Lockout Threshold
Vcc input, disables A/D conversion, rising edge
Under-voltage Lockout Hysteresis
Power-On Reset Threshold
Vcc , falling edge
POR Threshold Hysteresis
Standby Supply Current
Logic inputs forced to Vcc or
GND
SMBus static
Hardware or software
standby, SMBCLK at 10kHz
Average Operating Supply Current
Auto-convert mode, average 0.25 conv/sec
measured over 4sec. Logic
inputs forced to Vcc or GND
2.0 conv/sec
Conversion Time
From stop bit to conversion complete(all channels)
Conversion Rate Timing Error
Auto-convert mode
Remote-Diode Source Current
DXP forced to 1.5V
High level
Low level
Fan Controller
Supply voltage
VCC
Shutdown current
Both fans’ speed = 0rpm
MOSFET on resistance
Each channel
Short-circuit current limit
Each channel
Input logic low
VIL
Input logic high
VIH
Average Output current
Each channel
FG input Positive-going threshold voltage
VCC=5V
FG input Negative-going threshold voltage
VCC=5V
FG input Hysteresis voltage
VCC=5V
MIN TYP MAX UNITS
8 Bits
-5 5 °C
-3 3
-3.5 3.5 °C
4.5 5 5.5 V
2.6 2.8 2.95 V
50 mV
1.0 1.7 2.5 V
50 mV
3 10
200 µA
250 300
300 350
µA
94 125 156
-25 25
120 160 200
15 20 25
ms
%
µA
4.5 5 5.5 V
2 5 µA
0.2 0.25
0.5 A
0.8 V
2.4 V
350 mA
1.8 V
0.7 V
1.1 V
Ver 1.3
Oct 28, 2002
TEL: 886-3-5788833
http://www.gmt.com.tw
3


3Pages


G768 電子部品, 半導体
Global Mixed-mode Technology Inc.
OUT1
FG1
FAN CONTROL
VCC
CONTROL
LOGIC
FAN CONTROL
SMBUS
REGISTERS
G768B
CLK
OUT2
FG2
SMBCLK
SMBDATA
ALERT
DXP1
DXP2
DXN
INTERNAL GROUND
+
+
MUX
+
+
ADC
Fig 1. Functional Diagram
RESET
CIRCUIT
RESET
A/D Conversion Sequence
If a Start command is written (or generated automati-
cally in the free-running auto-convert mode), all three
channels are converted, and the results of all meas-
urements are available after the end of conversion. A
BUSY status bit in the status byte shows that the de-
vice is actually performing a new conversion; however,
even if the ADC is busy, the results of the previous
conversion are always available.
Remote-Diode Selection
Temperature accuracy depends on having a
good-quality, diode-connected small-signal transistor.
Accuracy has been experimentally verified for all of
the devices listed in Table 1. The G768B can also di-
rectly measure the die temperature of CPUs and other
integrated circuits having on-board tempera-
ture-sensing diodes. The transistor must be a
small-signal type with a relatively high forward voltage;
otherwise, the A/D input voltage range can be violated.
The forward voltage must be greater than 0.25V at
10µA; check to ensure this is true at the highest ex-
pected temperature. The forward voltage must be less
than 0.95V at 200A; check to ensure this is true at the
lowest expected temperature. Large power transistors
don't work at all. Also, ensure that the base resistance
is less than 100. Tight specifications for forward
current gain (+50 to +150, for example) indicate that
the manufacturer has good process controls and that
the devices have consistent VBE characteristics.
Thermal Mass and Self-Heating
Thermal mass can seriously degrade the G768B's
effective accuracy. The thermal time constant of the
SSOP-16 package is about 140sec in still air. For the
G768B junction temperature to settle to within +1°C
after a sudden +100°C change requires about five
time constants or 12 minutes. The use of smaller
packages for remote sensors, such as SOT23s, im-
proves the situation. Take care to account for thermal
gradients between the heat source and the sensor,
and ensure that stray air current across the sensor
package do not interfere with measurement accuracy.
Self-heating can significantly affect the measurement
accuracy. Remote-sensor self-heating due to the di-
ode current source is negligible. For the local diode,
the worst-case error occurs when auto converting at
the fastest rate and simultaneously sinking maximum
current at the ALERT output, and both fans are work-
ing at low speeds.
Table 1. Remote-Sensor Transistor Manufacturers
MANUFACTURER
MODEL NUMBER
Philips
PMBS 3904
Motorola(USA)
MMBT3904
National Semiconductor(USA) MMBT3904
Note:Transistors must be diode-connected (base short
-ed to collector).
Ver 1.3
Oct 28, 2002
TEL: 886-3-5788833
http://www.gmt.com.tw
6

6 Page



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