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 OPA, and then conversion using an ADC, 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 OPA, and then conversion by an ADC, the measured value is one representing body impedance, which is used to calculate the corresponding body fat value.

The device, which integrates the body fat scale circuitry, is a Flash Memory A/D type 8-bit high performance RISC architecture MCU includes a multi-channel 20-bit Delta-sigma A/D (ΔΣA/D) converter, which is designed for applications that interface directly to analog signals and which require a low noise and high accuracy analog to digital converter.

Offering users the convenience of Flash Memory multi-programming features, this device also includes a wide range of functions and features. Other memory includes an area of RAM Data Memory as well as an area of EEPROM memory for storage of non-volatile data such as serial numbers, calibration data etc.

A full choice of various internal and external oscillator functions is provided including a fully integrated system oscillator which requires no external components for its implementation. The ability to operate and switch dynamically between a range of operating modes using different clock sources gives users the ability to optimize MCU operation and minimize power consumption.