Ver 4.3

Oct 28, 2002

TEL: 886-3-5788833

http://www.gmt.com.tw

4

G760A

Global Mixed-mode Technology Inc.

Internal Registers

This IC provides 3 SMBus registers.

1.Programmed fan speed register:(SET_CNT,address:00b)

This register is a read/write register, it contains the

count number of the desired fan speed. Power up

default is FFh.

2.Actual fan speed register: (ACT_CNT, address: 01b)

This register is read only. It contains the count number of

the actual fan speed. Power up default is FFh.

3.Fan status register: (FAN_STA , address : 10b)

This register is read only. Its bit 0 is set to 1 when

the actual fan speed is ±20% outside the desired

speed. Its bit 1 is set to 1 when fan speed is be-

low

1920 rpm. Power up default is 10b.

SMBus Address

The SMBus address of this chip is fixed to7Ch (01111100b) for write and 7Dh(01111101b) for read.

SMBus Timing

(a) Typical Pointer Set Followed by Immediate Read

(b) Typical 1-Byte Read with Preset Pointer

(a) Typical Pointer Set Followed by Immediate Read

(b) Register Write

9

1

9

1

D0

Start

by

Master

Address Byte

R/W

Ack

by

G760

Data Byte

No Ack

by

Master

D7

Stop

Cond

by

Master

0

1

1

1

11

0

D1

D2

D3

D4

D5

D6

SMBCLK

SMBDATA

9

1

9

1

D0

Start

by

Master

Address Byte

R/W

Ack

by

G760

Data Byte

No Ack

by

Master

D7

Stop

Cond

by

Master

0

1

1

1

11

0

D1

D2

D3

D4

D5

D6

SMBCLK

SMBDATA

SMBDATA

Start

by

Master

Address Byte

Ack

by

G760

Pointer Byte

Ack

by

G760

9

1

9

1

0

0

0

0

0

0

R/W

0

1

1

1

11

0

SMBCLK

D0

D1

Repeat

Start

by

Master

Address Byte

Ack

by

G760

Data Byte

No Ack

by

Master

Stop

Cond

by

Master

1

9

1

9

R/W

0

1

1

1

11

0

D0

D1

D2

D3

D4

D5

D6

D7

SMBDATA

Start

by

Master

Address Byte

Ack

by

G760

Pointer Byte

Ack

by

G760

9

1

9

1

0

0

0

0

0

0

R/W

0

1

1

1

11

0

SMBCLK

D0

D1

Repeat

Start

by

Master

Address Byte

Ack

by

G760

Data Byte

No Ack

by

Master

Stop

Cond

by

Master

1

9

1

9

R/W

0

1

1

1

11

0

D0

D1

D2

D3

D4

D5

D6

D7

Repeat

Start

by

Master

Address Byte

Ack

by

G760

Data Byte

No Ack

by

Master

Stop

Cond

by

Master

1

9

1

9

R/W

0

1

1

1

11

0

D0

D1

D2

D3

D4

D5

D6

D7

Start

by

Master

Address Byte

Ack

by

G760

Pointer Byte

Ack

by

G760

No Ack

by

Master

Stop

Cond

by

Master

Address Byte

9

1

9

1

9

1

9

D0

D7

0

0

0

0

0

0

Data Byte

Ack

by

G760

SMBCLK

SMBDATA

R/W

0

1

1

1

11

0

0

1

1

1

11

0

D1

D2

D3

D4

D5

D6

R/W

D0

D1

Start

by

Master

Address Byte

Ack

by

G760

Pointer Byte

Ack

by

G760

No Ack

by

Master

Stop

Cond

by

Master

Address Byte

Address Byte

9

1

9

1

9

1

9

D0

D7

0

0

0

0

0

0

Data Byte

Data Byte

Ack

by

G760

SMBCLK

SMBDATA

R/W

0

1

1

1

11

0

0

1

1

1

11

0

D1

D2

D3

D4

D5

D6

R/W

D0

D1

9

1

9

1

9

1

Start

by

Master

Address Byte

R/W

Ack

by

G760

Pointer Byte

Ack

by

Master

Ack

by

G760

Stop

Cond

by

Master

Configuration Byte

0

0

0

0

0

0

0

1

1

1

1

1

0

D0

D7

D0

D1

D2

D3

D4

D5

D6

D1

SMBCLK

SMBDATA

9

1

9

1

9

1

Start

by

Master

Address Byte

R/W

Ack

by

G760

Pointer Byte

Ack

by

Master

Ack

by

G760

Stop

Cond

by

Master

Configuration Byte

Configuration Byte

0

0

0

0

0

0

0

1

1

1

1

1

0

D0

D7

D0

D1

D2

D3

D4

D5

D6

D1

SMBCLK

SMBDATA