MCP3208 is a 12-bit 8-channel SAR based Analog to Digital converter (ADC). ADC has SPI interface which can be used to communicate with the controller. In this connectivity, Micro controller is a master and ADC is a slave. MCP3208 is available in two different packages - SOIC and PDIP
As we can see from the schematic, input to ADC is from a 1x8 1.27mm pitch connector. The input can be either singled ended or differential. In case all the inputs are differential, MCP3208 supports 4 differential input channels. In differential mode, it is actually a pseudo-differential input where one pin is IN+ and second pin is IN-.
MCP3208 can operate between 2.7V to 5V. In the above circuit, MCP3208 is connected to 5V. The reference voltage input VREF can also be provided up to maximum operating voltage and in the circuit above it is provided same as 5V. This meant the analog input to ADC can have level up to 5V max. beyond which ADC conversion is restricted.
In the above circuit we can see the SPI signals connected to a 1.27mm pitch connector (P2). Optionally, CS pin can have a pull-up to supply voltage so that the chip is disabled under normal condition. Decoupling capacitors (C1,C2) are provided near the connector (P2) and MCP3208 (U1) and these capacitors selection actually depends on the noise on the board. 0.1uF is used as the starting point which is commonly used in all the embedded boards.
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