Microcontroller aims for metering applications

Sunrise Electronics has a new microcontroller from NEC offering extremely low power and onboard features that make it ideal for designing into metering and control applications.

Sunrise Electronics has a new microcontroller from NEC offering extremely low power and onboard features that make it ideal for designing into metering and control applications.

Metering is a growing application area for microcontrollers, including utility meters, such as water meters, gas meters and devices for heating cost allocation as well as portable healthcare devices such as blood pressure and heart rate monitoring.

These have in common that the microcontroller spends most of its life in idle mode, waking up only briefly to take a reading.

As these devices are often expected to run for as long as 10 years without battery replacement, the critical factor is power consumption in idle mode, a value that directly influences battery life.

The uPD789881 is a new member of NEC's successful 78K/OS family developed to provide the key features needed in metering applications.

Extremely long battery life can be achieved with designs using the uPD789881, which offers a full speed operating power consumption of only 21uA, declining to 0.9uA on standby from a power source between 2.7 and 3.6V.

Despite this low power operation, the device boasts a full complement of on-chip features including LCD driving capability of up to 104 segments (26 x 4).

It also has an onboard R/C oscillator, two 8bit and one 16bit timer counters and a single channel watchdog timer.

Onboard memory includes 16Kbyte of program ROM, 512byte of high-speed RAM and a dedicated display memory of 26 x 4bit.

A variant with Flash program memory is also available.

Instruction cycle times vary from 4us with a main clock frequency of 500kHz down to 31us at a subsystem clock frequency of (131kHz x 4), compatible with standard system designs and low-cost components.

Supplied in a small outline package with only 64 pins, for surface mounting, the uPD789881 is ideal for compact designs.

More comprehensive data, design-in support and development tools are all available from Sunrise Electronics now.

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