How does the ADC0809 work?

Answer 1

The ADC 0804 A/D Converter is an 8bit A/D converter that uses successive approximation to convert the analog inputs to the digital output. The basic block diagram of the function of the successive approximation A/D Converter is shown in the figure above. The ADC0804 has four major sections namely the Comparator, the control logic, the digital counter and a 256R ladder D/A converter. For any analog input, the control logic will trigger the digital counter to start incrementing from zero count and these digital values are converted to analog form through a 256R ladder network. This 256R network consists of a number of resistors of fixed incremental resistance that produce a representative staircase type waveform based on the output of the digital counter. The output of the ladder network then enters the comparator which has the role of comparing the input analog to the analog output of the D/A Converter. When the staircase wave form exceeds the input voltage, the comparator sends a signal to the control logic to stop counting. The value of the digital counter at the time when the comparator sends the 'stop count' signal is the digital representation of the input voltage.

Answer 2

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