5

Digital interfaces

The STTS22H communicates over a 2-wire serial interface compatible with the SMBus 3.0 standard and I²C

standard.

5.1

SMBus interface

5.1.1

SMBus protocol

The STTS22H communicates over a 2-wire serial interface compatible with the SMBus standard. Temperature

data, alarm limits and configuration information are communicated over the bus. A detailed timing diagram is

shown below in following figure.

P

S

P

S - start condition

P - stop condition

TBUF

THD; STA

TLOW

TR

THIGH

THD; STA

TF

TSU:STO

TSU:STA

TSU:DAT

THD:DAT

S

SMCLK

SMDATA

The STTS22H supports standard SMBus 3.0 protocols (see corresponding tables in the following sections).

•

WRITE byte

•

READ byte

•

SEND byte

•

RECEIVE byte

•

Alert response address

5.1.2

WRITE byte

The WRITE byte protocol is used to write one byte of data to the registers as shown in the following table. ACK

data are sent by the STTS22H while all other data are sent by the host.

Start

Slave

address

WR

ACK

Register

address

ACK

data

ACK

stop

1 bit

7 bits

1 bit

1 bit

8 bits

1 bit

8 bits

1 bit

1 bit

STTS22H

Digital interfaces

DS12606 - Rev 4

page 8/29