GMT G7931 Two remote and one local temperature sensors and 3/4 fan controllers with smbus interface Datasheet

G7931/G7932
Global Mixed-mode Technology Inc.
Two Remote and One Local Temperature Sensors
and 3/4 Fan Controllers with SMBus Interface
Features
General Description
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The G7931/G7932 contains 3 precise digital thermometers,
3/4 fan controllers, fan failure detection.
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Measures Two Remote and One Local Temperatures
Adjustable Offset for Each Sensor via SMBus
Accuracy: Remote ±1°C (+20°C to +80°C)
±3°C (-10°C to +120°C)
+4.5V to +5.5V Supply Range
Alert Signal for Diode Fault, Fan Fail, and Fan
Out of Control
Supports SMBus Alert Response
Fan Drivers Using Linear Control Algorithm
Closed Loop Speed Control and programmable
8 Bits Open Loop Voltage Control for Fan
Wide speed control range for Fan, Accuracy
within 2%, when FANx_SET_CNT > 50
Internal Current-limit and Over-temperature
Protection for the Fan Controllers
Build-In Inverters for Driving Crystal
Optional Internal Clock Accuracy ±3% from 20°C to
80°C at 5V VCC
20-Pin TSSOP Package
The thermometers report the temperature of 2 remote sensors and 1 local sensor. The remote sensors are diode-connected transistors typically a low-cost, easily
mounted 2N3904 NPN type or the diode built-in in CPU.
Remote accuracy is ±1°C for multiple transistor manufacturer. Local accuracy is ±3°C. The G7931/G7932 also support offset adjust function via SMBus to fix the error due to
different CPU diode or parasitic resistors.
The 2-wire serial interface accepts standard System Management Bus (SMBusTM) Write Byte, Read Byte, Send
Byte, and Receive Byte commands. The SMBus address
is 70h 72h for write and 7173hh for read for G7932.For
G7931, ADD0 pin selects 3 different SMBus addresses.
(see “ SMBus Digital Interface” section)
G7931/G7932 contains 3/4 fan controllers which perform
closed-loop and open-loop control. G7931/ G7932 determines the current fan speed based on the FG inputs and an
externally supplied 32.768kHz clock. The driving ability is
5mA. G7931/G7932 also provides ALERT for fan fail and out
of control event.
Applications
„ Projector, LCD TV, PDP TV
„ Desktop and Notebook
„ Central Office Computers
„ Telecom Equipments
„ Industrial Controls
„ LAN Servers
SMBusTM is a trademark of Intel Corp
Ordering Information
ORDER
NUMBER
MARKING
TEMP.
RANGE
PACKAGE
(Green)
G7931D51U
G7932D51U
G7931
G7932
-55°C to +125°C
-55°C to +125°C
TSSOP-20
TSSOP-20
Note: D5: TSSOP-20
1: Bonding Code
U: Tape & Reel
GMT Inc. does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and GMT Inc. reserves the right at
any time without notice to change said circuitry and specifications.
Pin Configuration
G7931
G7932
FAN2
1
20
FAN3
FAN2
1
20
FAN3
FG2
2
19
FG3
2
19
FG3
FAN1
FG1
3
18
NC
FG2
FAN1
3
18
FAN4
4
ADD0
FG1
4
17
GND
5
16
FG4
GND
6
15
VCC
7
SCL
SDA
X2
ALERT
NC
DXP1
5
17
16
6
15
VCC
ALERT
NC
7
14
SCL
DXP1
SGND1
8
13
SDA
SGND1
8
14
13
DXP2
9
12
X2
DXP2
9
12
SGND2
10
11
X1/CLK
SGND2
10
TSSOP-20
11 X1/CLK
TSSOP-20
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Oct 18, 2010
1
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