Microchip targets active-current reduction in PIC24F expansion
Colin Holland, EE Times -- EDN, February 2, 2012
Microchip has expanded its XLP (extreme-low-power) microcontroller portfolio with the 16-bit PIC24F GA3 family. The devices feature 150-μA/MHz active current and as many as six DMA (direct-memory-access) channels. The family adds a low-power sleep mode with RAM retention as low as 330 nA, and the devices are the first PIC microcontrollers with battery-voltage backup of the on-chip real-time-clock calendar.The XLP technology has traditionally concentrated on reducing static current, according to Don Schneider, product-marketing manager with the advanced-microcontroller division of Microchip Technology. This development, however, reduces active current. Standard XLP modes include run, idle, doze and sleep, and deep sleep. The intermediate step between the sleep mode and the deep-sleep mode allows the devices to maintain RAM and allows some of the peripherals to operate at low current.
The new PIC24F units also
integrate an LCD driver to
directly drive as many as 480
segments, with an eight-common-drive capability, enabling
more informative and flexible
displays that include descriptive icons and scrolling. The
60×8-segment LCD driver
improves on earlier units’
42×4-segment driver. The units
also include a CTMU (charge-time-measurement unit) with
a constant-current source for
mTouch capacitive sensing,
ultrasonic flow measurement,
and many other sensors.The device includes as many as 24 channels of 12-bit ADC. The ADC includes a threshold-detection function that allows the ADC to wake the CPU when it reaches a threshold window. The function is useful when using the CTMU in a capacitive-touch application. It allows you to monitor the button or proximity sensor when the device is in sleep mode and can wake when it reaches a threshold value. A couple of additional ADC channels operate internally for internal temperature sensors and similar functions.
The PIC24F GA3 devices target use in consumer thermostats, door locks, and home automation; industrial products, such as security, wired and wireless sensors, and controls; portable medical devices and medical-diagnostic equipment; and metering products, including e-meters, energy monitoring, automated meter reading, and meters for gas, water, or heat. Power meters are constantly on and monitoring the power. They must meet a 10 VA IEC current budget, and many power companies are asking for still lower-power numbers. To achieve the 10-VA target, a microcontroller can consume only approximately 10 mA or less. Many microcontrollers must operate at reduced speed to stay within this budget.
The GA3 family can operate at its full 16 MIPS with 4.9 mA. This ability allows the device to either add functions, perhaps running more complex code or a communication stack, or continue running at a lower speed and conserve even more power. The DMA channels on the device enable it to move data to peripherals in parallel with the CPU’s operation, freeing the CPU for other functions. An example of a DMA operation could be the transfer of data from the device RAM to a serial channel for an RF-communication stack. Microchip has added these devices to its battery-life-estimator lineup.
To aid development, the PIC24FJ128GA310 plug-in module is available for $25 and works with the company’s Explorer 16 development board. To evaluate or develop designs with a 480-segment LCD, the LCD Explorer development board is available for $125. Samples and volume production are available with versions having 64 or 128 kbytes of flash. The PIC24FJXXXGA306 devices are available in 64-pin QFN and TQFP packages; PIC24FJXXGA308 versions are available in 80-pin TQFP packages, and the PIC24FJXXXGA310 is available in 100-pin TQFP and 121-ball BGA packages.
Microchip Technology Inc
Talkback
