New Industry Products

TI & NXP Products Reveal Trend In Low-Power Devices Enabling Use Of Energy Harvesting

June 09, 2008 by Jeff Shepard

New product releases from Texas Instruments (a low-power microprocessor) and NXP Semiconductors (a real-time clock) exemplify a trend in low-power devices that are enabling the use of energy harvesting devices.

TI announced its ultra-low power MSP430 microcontrollers (MCU), offering what is said to be the industry’s lowest power consumption for devices that can provide up to 25 MHz of peak performance. With as low as 160µA/MHz active power consumption and 1.5µA in standby mode, TI’s MSP430F5xx devices are said to enable longer battery life and the ability to use smaller batteries for portable applications or no batteries at all for energy harvesting systems that run off of solar power, vibration energy or human body temperature.

The new MSP430F5xx generation delivers 56% more processing performance than previous 1xx, 2xx or 4xx MSP430 device generations to help the system perform demanding tasks while also operating from very limited power sources. Designers can tap into peak execution performance of up to 25 MHz while consuming as low as 160uA/MHz. A wake up time of less than 5µs with full status retention from both standby and sleep modes provides full performance on demand and instant reaction to events like external interrupts. Multi-channel direct memory access (DMA) permits the exchange of data with peripherals while the core remains in low-power modes.

Future F5xx devices will include peripherals such as USB, encryption, RF and LCD interfaces. A new high-resolution timer will offer advanced processing capabilities to enable applications like voice-activated home security systems. Up to one megabyte (MB) of linear memory mapping enables robust user interfaces, as well as applications for ZigBee® and other low-power RF sensor networks. F54xx devices offer up to 16 kilobytes of RAM and up to 256 KB Flash, doubling Flash and RAM available on previous MSP430F2xx, F1xx and F4xx devices. 5xx devices offer read/erase/write capability down to 1.8 V and with AAA battery-based application, Flash write is possible down to the battery end of life voltage of 0.9V.

NXP introduced what it describes as the industry’s best low-power performance real-time clock (RTC) chips with SPI bus interface – the PCF2123. Operating at a current of less than 100nA (0.15uW) on a 1.5V power supply, the real-time clock comes in a 3 x 3 x 1mm package, making it suitable for battery operation and handheld applications to keep track of time, when the equipment is powered down. The small size and low-power requirement of the PCF2123 are said to make it a good choice for applications including home-use medical devices such as blood pressure monitors, portable phones, PDAs and similar compact portable electronics products where space and power are critical, while the variety of features makes it suitable for industrial systems as well as white goods.

Features of the PCF2123 real-time-clock include a freely programmable alarm and timer function that gives designers the option to generate a wake-up signal on an interrupt pin. A programmable offset register also allows fine-tuning of the clock and frequency adjustment. The seconds, minutes, hours, days, weekdays, months and years registers are all coded in binary-coded decimal (BCD) format for easy conversion to decimal digits for printing or display and faster decimal calculations. Data is transferred serially via an SPI bus with a maximum data rate of 6.25 Mbits per second.

The PCF2123 is a CMOS real-time clock and calendar optimized for low power consumption. It functions as the time manager accurately keeping time, controlling the periodic wake-up of the microcontroller core from hibernation mode, and providing a watchdog function to independently monitor microcontroller tasks. With power consumption at less than 0.15uW the RTC can be powered by a very small battery cell or a small super-cap. Housed in tiny 3 x 3 x 1mm leadless package, the RTC is said to fit nearly anywhere minimizing the space needed to host this timing and measurement function.