The ADuC841/ADuC842/ADuC8431 are complete smart transducer front ends， that integrates a high performance selfcalibrating multichannel ADC， a dual DAC， and an optimized single-cycle 20 MHz 8-bit MCU （8051 instruction set compatible） on a single chip. The ADuC841 and ADuC842 are identical with the exception of the clock oscillator circuit; the ADuC841 is clocked directly from an external crystal up to 20 MHz whereas the ADuC842 uses a 32 kHz crystal with an on-chip PLL generating a programmable core clock up to 16.78 MHz. The ADuC843 is identical to the ADuC842 except that the ADuC843 has no analog DAC outputs. The microcontroller is an optimized 8052 core offering up to 20 MIPS peak performance. Three different memory options are available offering up to 62 kBytes of nonvolatile Flash/EE program memory. Four kBytes of nonvolatile Flash/EE data memory， 256 bytes RAM， and 2 kBytes of extended RAM are also integrated on-chip.