Design For Always-On

Designing for low power is such an interesting area because, while it might be frustrating, one size — or approach, in this case — does not fit all.

It is a balancing act to weigh the design objectives against what is possible in the process.

NXP, which launched a series of low power MCUs today aimed at the sensor-processing market, has been focusing on optimizing power consumption for all of its MCU products, according to Ross Bannatyne, general manager, Mass Market PL MCU at NXP, because so many of them are used in handheld, portable devices. “Power consumption has become one of the main design objectives for engineers who both create systems and chips that go into those. From a product perspective, there’s a big drive towards lower power and that’s being complemented by the development and tools environment that goes around these chips to make it easier for engineers who are developing with these chips to be able to keep a good handle on how much power they are consuming with the product in the different operating modes.”

He finds the way the technology has been developing quite interesting because, “as these semiconductor devices go into successively smaller and smaller processing geometries, typically one of the symptoms that you get when you shrink the processing geometries that they leakage within the part goes up. However, the active mode current — when you’re running the part at high speed — tends to go down. So you’ve got a couple of offsetting things that happen.”

Bannatyne said this was one of the big focuses in the design of the new chip: to optimize both the power-down current and to optimize the active mode current. “It’s really important to do that because in most applications that are battery powered, designers don’t have the luxury of being able to pick one of those operating modes and optimizing for it. They really want to be consuming very low battery power, both when they are powered down and maybe monitoring some inputs from some sensors, but then when they gather the sensor data, they need to power up very quickly and analyze that data and perhaps do some signal processing on it and some serious number crunching. That takes active mode current, then they need to get back to sleep again quickly.”

We want to hear from you. Let us know your experiences with balancing design objectives against what is possible with the process and the design flow.