The 8bit core uses a 32bit wide interface to flash for the first time so that multiple instructions can be accessed quickly and the flash shut down between operations to save power, and it uses hardwired accelerators for key functions to reduce the energy consumption and allow the core to stay in sleep mode as long as possible. Silicon Labs has also designed an on-chip DC-DC buck converter to improve the conversion efficiency to 85% and has used dedicated high voltage standard cells to reduce the static and leakage power. This converter can supply up to 250 mW to the core and other circuits in the system such as an RF transceiver and can be controlled independently of the core to shut down multiple power planes.
All this allows 40% lower system current and a 65% higher battery life in a range of applications, mostly wireless metering with a battery life of over 20 years, but also wireless security, home and building automation, portable medical and asset tracking products, says Ken Odland, director of marketing for MCUs at Silicon Labs.
The changes are across the core and peripherals. For example for applications with an LCD, SiLabs has modified the bias generator in the LCD controller so that charge from individual segments can be moved around in the chip rather than draining to ground and requiring more power from the DC-DC converter.
An on-chip Dedicated Packet Processing Engine (DPPE) with hardware acceleration blocks enables more than a fivefold increase in RF message processing speed and allows the CPU to remain idle during transactions, reducing the active time and the current load on the battery. The MCUs also include a low-power pulse counter that operates autonomously in sleep mode without CPU intervention. The on-chip pulse counter is especially useful in reducing power in utility metering applications that use pulse trains or switch closures while monitoring fluid flow.
The Si102x/3x wireless MCUs (below)