EMC2103 datasheet(18/85 Pages) MICROCHIP

18 / 85 page

RPM-Based Fan Controller with Hardware Thermal Shutdown

Datasheet

 2013 Microchip Technology Inc.

DS0005250A-page 18

Chapter 4 Communications

4.1

System Management Bus Interface Protocol

The EMC2103 communicates with a host controller, such as an SIO, through the SMBus. The SMBus

is a two-wire serial communication protocol between a computer host and its peripheral devices. A

detailed timing diagram is shown in Figure 4.1. Stretching of the SMCLK signal is supported, however

the EMC2103 will not stretch the clock signal.

The EMC2103 contains a single SMBus interface. The EMC2103 client interfaces are SMBus 2.0

compatible and support Send Byte, Read Byte, Receive Byte and the Alert Response Address as valid

protocols. These protocols are used as shown below.

All of the below protocols use the convention in Table 4.1.

4.2

Write Byte

The Write Byte is used to write one byte of data to the registers as shown below Table 4.2:

Figure 4.1 SMBus Timing Diagram

Table 4.1 Protocol Format

DATA SENT

TO DEVICE

DATA SENT TO

THE HOST

# of bits sent

Table 4.2 Write Byte Protocol

START

SLAVE

ADDRESS

ACK

ADDRESS

ACK

DATA

ACK

STOP

0 -> 1

0101_110

0 -> 1

XXh

1 -> 0

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