Atmel has developed a new series of high-performance, ultra-low power ARM7TDMI-based microcontrollers, the AT91SAM7L series, embedding power switches controlling multiple power islands and programmable voltage regulators to reduce power consumption in active and standby modes.
The AT91SAM7L series features innovative power reduction techniques for both active and standby modes. In active mode, the power consumption is optimised via a programmable operating voltage, operating frequency, and peripheral clock activity, and the use of DMA instead of the CPU for data transfers. The SAM7L operates in single supply mode down to 1,8 V and consumes 0,5 mA/MHz in active mode when executing code out of its Flash memory.
The power consumption in the different standby modes is controlled via power switches, scalable voltage regulators, and the use of sampling techniques on voltage monitors, power-on reset (POR) and brown-out detector (BOD) instead of continuous measurement. In power down mode, the MCU consumes only a typical 100 nA, which is believed to be a unique feature for 32-bit MCUs.
In power-down mode, only the fast wake-up pin is supplied, allowing a system wake-up through a simple pushbutton. In backup mode, only the supply controller, the zero-power POR and the 32 kHz oscillator remain running. The RTC, the 2K backup SRAM, the BOD, the charge pump, the LCD voltage regulator and the LCD controller can be set on or off separately. This mode can be used when time, context or display need to be saved even if the main application is not running. In wait mode, the 2 MHz RC oscillator provides a rapid wake-up time for fast external event management.
The devices embed LCD features which include a segment LCD controller, built-in drivers and the programmable LCD power supply for contrast control comprising a regulated charge pump and an adjustable voltage regulator. It is intended for monochrome passive LCDs with up to 10 common terminals and up to 40 segment terminals.
The AT91SAM7L series has two members, the AT91SAM7L128 and the AT91SAM7L64 with respectively 128 KBytes and 64 KBytes of Flash memory. The series also integrates a wide range of peripheral functions, including USART, SPI, timer counter, RTC and analog-to-digital converters. The system controller includes a reset controller capable of managing the power-on sequence. Correct device operation can be monitored by a built-in BOD and a watchdog timer running off an integrated oscillator.
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