ADT7470 データシートの表示（PDF） - Analog Devices

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ADT7470

Temperature Sensor Hub and Fan Controller

Analog Devices 

ADT7470

Data Sheet

during the low period before the 10th clock pulse, then

high during the 10th clock pulse to assert a stop condition.

Any number of bytes of data can be transferred over the serial

bus in one operation. However, it is not possible to mix read

and write in one operation, because the type of operation is

determined at the beginning and subsequently cannot be

changed without starting a new operation.

In the ADT7470, write operations contain either one or two

bytes, and read operations contain one byte and perform the

following functions.

1

9

SCL

To write data to one of the device data registers or read data

from it, the address pointer register must be set so that the

correct data register is addressed. Then data can be written into

that register or read from it. The first byte of a write operation

always contains an address that is stored in the address pointer

register. If data is to be written to the device, the write operation

contains a second data byte that is written to the register selected

by the address pointer register.

This is illustrated in Figure 7. The device address is sent over the

bus followed by R/W set to 0. This is followed by two data bytes.

1

9

SDA

0

1

START BY

MASTER

0

1

1 A1 A0 R/W

D7

FRAME 1

SERIAL BUS ADDRESS

BYTE

ACK. BY

ADT7470

1

SCL (CONTINUED)

D6 D5 D4 D3 D2 D1 D0

FRAME 2

ADDRESS POINTER REGISTER BYTE

ACK. BY

ADT7470

9

SDA (CONTINUED)

D7 D6 D5 D4 D3 D2 D1 D0

FRAME 3

DATA

BYTE

ACK. BY STOP BY

ADT7470 MASTER

Figure 7. Writing a Register Address to the Address Pointer Register, Then Writing Data to the Selected Register

1

9

1

9

SCL

SDA

0

1

START BY

MASTER

0

1

1

A1 A0 R/W

D7 D6 D5 D4 D3 D2 D1 D0

FRAME 1

SERIAL BUS ADDRESS

BYTE

ACK. BY

ADT7470

FRAME 2

ADDRESS POINTER REGISTER BYTE

Figure 8. Writing to the Address Pointer Register Only

ACK. BY STOP BY

ADT7470 MASTER

1

9

1

9

SCL

SDA

0

1

START BY

MASTER

0

1

1

A1 A0 R/W

D7 D6 D5 D4 D3 D2 D1

FRAME 1

SERIAL BUS ADDRESS

BYTE

ACK. BY

ADT7470

FRAME 2

DATA BYTE FROM

ADT7470

Figure 9. Reading Data from a Previously Selected Register

D0

NO ACK. STOP BY

BY MASTER MASTER

Rev. E | Page 10 of 40

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