The devices are specifically designed for four-electrode AC Body Fat Scale applications. Measuring body fat uses a technique whereby an AC current flowing through the human body is measured and then used to calculate a body fat value. The specialised circuits to do this are a weight measurement circuit and a fat measurement circuit. The weight measurement circuit uses an external load cell to output a signal, which after amplification by an operational amplifier, and then conversion using an A/D converter, reads the corresponding value as the calculated weight. The fat measurement circuit uses an AC signal via an electrode slice to flow through human body. After amplification by an internal operational amplifier, and then conversion by an A/D converter, the measured value is one representing body impedance, which is used to calculate the corresponding body fat value.

The devices are Flash Memory I/O type 8-bit high performance RISC architecture microcontrollers which include a multi-channel 24-bit Delta Sigma A/D converter, designed for applications that interface directly to analog signals and which require a low noise and high accuracy analog-todigital converter. Offering users the convenience of Flash Memory multi-programming features, the devices also include a wide range of functions and features. Other memory includes an area of Data Memory as well as an area of true EEPROM memory for storage of non-volatile data such as serial numbers, calibration data etc.

Analog features include a multi-channel 24-bit Delta Sigma A/D converter and other circuitry specifically designed for Body Fat Scale applications. Up to two extremely flexible Timer Modules provide timing, pulse generation and PWM generation functions. Communication with the outside world is provided by including fully integrated SPI and UART interface functions, two popular interfaces which provide designers with a means of easy communication with external peripheral hardware. Protective features such as an internal Watchdog Timer, Low Voltage Reset and Low Voltage Detector coupled with excellent noise immunity and ESD protection ensure that reliable operation is maintained in hostile electrical environments.

A full choice of internal high and low oscillators functions are provided including two fully integrated system oscillators which require no external components for their implementation. The ability to operate and switch dynamically between a range of operating modes using different clock sources gives users the ability to optimise microcontroller operation and minimise power consumption.

The inclusion of flexible I/O programming features, Time-Base functions along with many other features ensure that only a minimum of external components is required for application implementation, resulting in reduced component costs and reductions in circuit board areas.