A System Management Bus controller is a two-wire bus found in personal computers and servers for lightweight communications. The SMBus controller enables the computer’s motherboard to communicate with low-speed devices such as the clock chips, fan or voltage sensors and the battery on a laptop computer.
The SMBus controller was first developed by Intel in 1995. It has a clock with a frequency range of 10 to 100KHZ. The SMBus controller can report different types of errors, save its state for a suspended result, accept control measures and return to its state. If the SMBus appears in the device manager with an error, it is an indication that the motherboard chipset drivers are not installed properly.
The SMBus controller is derived from an inter-integrated circuit bus. However, there are some variances in the specifications of the two buses. For example, the SMBus defines a clock low timeout of 35ms, while the inter-integrated circuit does not specify any clock timeout limit. Additionally, the SMBus controller has clock with a frequency of 10 to 100 kHz, while the inter-integrated circuit has clock frequency of 0 to 100 kHz. Other major differences between the two buses can be found in areas of operating modes and protocols.