G7951

G7951
Global Mixed-mode Technology Inc.
Three Remote Temperature Sensors and One PWM
Mode Fan Controllers with SMBus Serial Interface
Features
General Description
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Measures Three Remote Temperatures
Adjustable Offset for Each Sensor via SMBus
Accuracy: ±1°C (+ 60°C to + 100°C)
±3°C (- 10°C to + 120°C)
+4.5V to +5.5V Supply Range
Programmable Hardware Thermal Shutdown
for Sensor 2 and Programmable Software
Thermal Shutdown for Sensor 1,3.
SMBus 2-Wire Serial Interface with Writting
Protection Function.
Alert Signal for Diode Fault, Fan Fail, and Fan
Out of Control
Supports SMBus Alert Response
The G7951 contains 3 precise digital thermometers,
one fan controllers, hardware and software thermal
shutdown.
PWM Mode Speed Control
The 2-wire serial interface accepts standard System
Management Bus (SMBusTM) Write Byte, Read Byte,
Send Byte, and Receive Byte commands. G7951
SMBus address is 7ah for write and 7bh for read. And
supports writting protection function by command 20h
to prevent error behavior of µP.
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The thermometers report the temperature of 3 remote
sensors. 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. The G7951 also support offset adjust function
via SMBus to fix the error due to different CPU diode
or parasitic resistors.
Closed Loop Speed Control and programmable
8 Bits Open Loop PWM Duty cycle Control for
FAN
„ Wide Speed Control Range for FAN, Accuracy
within 2%, when SET_CNT1 > 50
„ Internal Current- limit and Over-temperature
Protection for the Fan
„ SSOP-16 & TQFN4X4-24 Package
G7951 contains one PWM mode fan controllers. FAN
controller performs closed-loop and open-loop control.
G7951 determines the current fan speed based on the
FG inputs and an externally supplied 32.768kHz clock.
G7951 also provide ALERT for fan fail and out of control
event.
Applications
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Desktop and Notebook
Central Office Computers
Telecom Equipment
Smart Battery Packs
Industrial Controls
LAN Servers
The G7951 provides hardware and software thermal shutdown. The hardware thermal shutdown is for the sensor 2.
The trigger point is set external resistors. The trigger points
of software thermal shutdown are set via SMBus. If thermal shutdown event occurs, THERM pin outputs low.
5
12
ALERT
DXP1
6
11
CLK
SGND1
7
10
THERM
DP2DN3
8
9
DN2DP3
DVCC
NC
NC
20
19
FOUT
16
SDA
VCC
4
DXP1
SGND1
Thermal
Pad
15
ALERT
5
14
CLK
6
13
THERM
12
VCC
3
NC
SDA
SCL
GND
11
13
4
SCL
NC
17
NC
14
18
2
9
GND
3
1
FG
10
FG
THERM_SET
NC
DVCC
NC
15
22
NC
2
24
THERM_SET
8
FOUT
7
16
DP2DN3
1
DN2DP3
NC
23 NC
G7951
21
Pin Configuration
G7951 TQFN4X4-24
SSOP-16
Note: Recommend connecting the Thermal Pad to
the Ground for excellent power dissipation.
SMBusTM is a trademark of Intel Corp.
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.1
Oct 18, 2010
1
Global Mixed-mode Technology Inc.
G7951
Ordering Information
ORDER
NUMBER
MARKING
TEMP.
RANGE
PACKAGE
(Green)
G7951S11U
G7951
-55°C to +125°C
SSOP-16
G7951R51U
7951
-55°C to +125°C
TQFN4X4-24
Note:S1:SSOP-16
R5: TQFN4X4-24
1: Bonding Code
U: Tape & Reel
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.1
Oct 18, 2010
2