The move to USB chargers is great but its power limitations also limit the supported applications. USB 3.0 increases the power requirements but Greenplug has better ideas for a more feature rich power management system. It does so by putting intelligence on both ends (Fig. 1) of the power problem. The approach includes an API called Greentalk and adds only a single wire to the power cable for bidirectional communication. The idea is to bring intelligent, adaptive power management to a range of appliances that can utilize a common power source.
The Greenptalk Load Implementation (GLI) provides load management and identification when connected to a Greentalk Hub Implementation (GHI). The GLI can operate on its own or communicate with a local CPU. Typical local processor applications would include laptops, tablets and netbooks or hand held devices like smart phones or media players. The former tend to have power requirements in excess of what a USB connection could provide.
The GHI supplies power to one or more GLI's. The cable connecting the devices includes a power pair plus a single, GreenComm's wire for Greentalk communication. The Greenplug Power Processor (GPP) is found in the GHI although the GPP or a stripped down version could also be placed in the GLI. The GPP (Fig. 2) is a full microcontroller with the GreenTalk system in ROM amd 80 Kbytes of RAM. There is also an SPI boot loader allowing a SPI serial flash-based application to manage the system. The GPP's ROM includes the Greenwire stack (Fig. 3). The system has a multithreaded hardware controller with a DSP SIMD instruction set. It also includes a multichannel 10-bit ADC and a PWM subsytem.
The 90nm GPP only uses 50mW and under 1mW when in sleep mode. It is available in a number of different package form factors.
The Greenplug API is used across a Greenwire connection but it can handle power management and monitoring across a range of platforms such as ZigBee.
The Greenplug 3-pin connector would be found on a GHI but the connector at the other end of the cable might be anything from another 3-pin plug to a USB connector. In the latter case, the connector would hide a GLI that includes a reduced feature set system. It could easily handle the USB power requirements.
The amount of power a Greenplug system could deliver depends upon the implementation but it can greatly exceed that available via a USB connection. This would allow a hub to handle a USB-based smart phone or the higher power requirements of a multicore laptop. The system could do this in a managed fashion delivering only the amount of power required by the load.