Ver: 2.0

Oct 18, 2010

TEL: 886-3-5788833

http://www.gmt.com.tw

1

G793/G794

Global Mixed-mode Technology Inc.

Two Remote and One Local Temperature Sensors

and 3/4 Fan Controllers with SMBus Interface

Features

Measures Two Remote and One Local Tem-

peratures

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

20-Pin TSSOP Package

Applications

Projector, LCD TV, PDP TV

Desktop and Notebook

Central Office Computers

Telecom Equipments

Industrial Controls

LAN Servers

General Description

The G793/G794 contains 3 precise digital thermome-

ters, 3/4 fan controllers, fan failure detection.

The thermometers report the temperature of 2 remote

sensors and 1 local sensor. The remote sensors are di-

ode-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 manu-

facturer. Local accuracy is ±3°C. The G793/G794 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 (SMBus

Send Byte, and Receive Byte commands. The SMBus

address is 72h for write and 73h for read.

G793/G794 contains 3/4 controllers. FAN controller per-

forms closed-loop and open-loop control. G793/G794

determines the current fan speed based on the FG inputs

and an externally supplied 32.768kHz clock. The driving

ability is 5mA. G793/G794 also provides ALERT for fan

fail and out of control event.

SMBus

Ordering Information

ORDER

NUMBER

MARKING

TEMP.

RANGE

PACKAGE

(Green)

G793D5U

G793

-55°C to +125°C

TSSOP-20

G794D5U

G794

-55°C to +125°C

TSSOP-20

Note: D5: TSSOP-20

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

FAN3

FG3

NC

GND

DVCC

SCL

FAN2

FAN1

FG1

ALERT

AVCC

DXP1

SGND1

DXP2

SGND2

G793

TSSOP-20

5

6

7

8

9

10

1

4

3

2

FG2

SDA

X2

X1/CLK

FAN3

FG3

FAN4

FG4

GND

DVCC

SCL

FAN2

FAN1

FG1

ALERT

AVCC

DXP1

SGND1

DXP2

SGND2

G794

TSSOP-20

13

20

19

18

17

16

15

5

6

7

8

9

10

1

4

3

2

14

FG2

SDA

11

12

X2

X1/CLK

NC

13

20

19

18

17

16

15

14

11

12

FAN3

FG3

NC

GND

DVCC

SCL

FAN2

FAN1

FG1

ALERT

AVCC

DXP1

SGND1

DXP2

SGND2

G793

TSSOP-20

5

6

7

8

9

10

1

4

3

2

FG2

SDA

X2

X1/CLK

FAN3

FG3

FAN4

FG4

GND

DVCC

SCL

FAN2

FAN1

FG1

ALERT

AVCC

DXP1

SGND1

DXP2

SGND2

G794

TSSOP-20

13

20

19

18

17

16

15

5

6

7

8

9

10

1

4

3

2

14

FG2

SDA

11

12

X2

X1/CLK

NC

13

20

19

18

17

16

15

14

11

12