system power management interface (control bus) (SPMI)

The Inter-IC bus, known as the I2C bus, is a now obsolete control bus for communication between integrated circuits (IC) of a system. It dates back to the 1980s and therefore no longer meets the increased demands of increasingly complex processors, ASICs (Application Specific Integrated Circuit) and System-on-Chips( SoC). As a result, National Semiconductor has developed faster and more agile bus techniques to replace the I2C bus.

In 2003, the company partnered with ARM and other companies to develop the PWI interface, PowerWise Interface, with Adaptive Voltage Scaling( AVS) for power management. Later, in 2008, under the leadership of the MIPI Alliance, Mobile Industry Processor Interface, the SPMI interface, System Power Management Interface, was introduced.

The SPMI interface is a power management standard for mobile electronics. This two- wire, serial interface is optimized for power management and general control tasks. It is sufficiently flexible in clock frequencies, which can range from 32 kHz to 26 MHz, without requiring the individual devices to be synchronized with each other. The nodes connected to the control bus are assigned to different classes. There is the master and two different slaves, one of which can send requests and the other cannot. The individual components connected to the bus have equal arbitration and the data traffic can be controlled by prioritization.