Let us list some of the important points about the ADC used in our embedded circuits:
- While the micro controllers have in-built ADC, there are micro controllers without internal ADC. In these cases, external ADC shall be used
- In case of external ADC, the interface between ADC and micro controller is either serial or parallel. Serial could be SPI, I2C
- ADC need clock for their operation. Clock can be internal or external. ADC with integrated clock doesn't need an external clock
- SAR ADC are most commonly used and low power consumption is one of the reason
- Resolution of an ADC is indicated by bit size, example 8-bit or 16-bit or 20-bit
- Resolution of an ADC is the minimum Analog value step that can be read by the ADC
- Sampling rate is one of the important parameter while selecting the ADC. Sampling rate is the rate at which input analog signals sampled by the ADC
- ADC shall have VREF pin which is the maximum analog voltage that can be given to ADC for conversion.
- Giving stable VREF is very important for accurate operation of the ADC
- Remember that VREF voltage should not be noisy
- Resolution of an ADC is given by VREF/(2^n - 1). n is the bit size of the ADC
- ADC inputs have options like single ended and differential. If the input is only singled ended, the negative input has to be grounded and input connected to positive pin
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