EMC2113 datasheet(17/88 Pages) MICROCHIP

17 / 88 page

RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown

Datasheet

 2013 Microchip Technology Inc.

DS20005251A-page 17

Chapter 5 SMBus Slave Interface

The EMC2113 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.

5.1

System Management Bus Interface Protocol

The EMC2113 contains an SMBus slave interface. A detailed timing diagram is shown in Figure 5.1,

"SMBus Timing Diagram". Stretching of the SMCLK signal is supported, however the EMC2113 will not

stretch the clock signal.

5.1.1

SMBus Start Bit

The SMBus Start bit is defined as a transition of the SMBus Data line from a logic ‘1’ state to a logic

‘0’ state while the SMBus Clock line is in a logic ‘1’ state.

5.1.2

SMBus Address and RD / WR Bit

The SMBus Address Byte consists of the 7-bit slave address followed by the RD / WR indicator bit. If

this RD / WR bit is a logic ‘0’, then the host device is writing data to the slave device. If this RD / WR

bit is a logic ‘1’, then the host device is reading data from the slave device.

The EMC2113 SMBus slave address is determined via the pull-up resistor connected to the

ADDR_SEL pin as shown Table 5.1, "ADDR_SEL Pin Decode".

Figure 5.1 SMBus Timing Diagram

Table 5.1 ADDR_SEL Pin Decode

PULL-UP RESISTOR VALUE

FAN CONTROL ADDRESS

4.7k Ohm ±5%

0101_100(r/w)

6.8k Ohm ±5%

0101_101(r/w)

10k Ohm ±5%

0101_110(r/w)

15k Ohm ±5%

1001_100(r/w)

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