Microchip MCP3204-BI/SL 12-Bit 4-Channel SPI ADC: Datasheet, Pinout, and Application Circuit Guide
The Microchip MCP3204-BI/SL is a highly versatile and widely adopted 12-bit analog-to-digital converter (ADC) that provides a perfect balance of resolution, speed, and cost-effectiveness for a multitude of embedded systems and data acquisition applications. Its 4 single-ended input channels or 2 pseudo-differential input channels offer flexibility for sensing multiple analog signals from sensors like thermistors, potentiometers, photodiodes, and current shunts. This guide delves into its key specifications, pinout, and a practical application circuit.
Datasheet Overview and Key Specifications
The MCP3204 operates on a 2.7V to 5.5V supply voltage, making it compatible with both 3.3V and 5V microcontroller (MCU) systems. Its 12-bit resolution provides 4,096 (2^12) possible digital output codes, enabling fine-grained measurement of analog signals.
A primary advantage of this ADC is its serial peripheral interface (SPI), which allows for communication with a host MCU using only a few digital I/O pins. This simplifies board layout and reduces the number of required MCU peripherals. Key performance characteristics from the datasheet include:
Sample Rate: Up to 100 kilosamples per second (ksps) at 5V.
Interface: SPI-compatible serial interface (supporting modes 0,0 and 1,1).
Input Channels: 4 single-ended or 2 pseudo-differential.
Integrated Sample-and-Hold: Ensures accurate capture of the instantaneous input voltage.
Low Power Consumption: Typical standby current of just 500 nA and active current of 400 μA at 5V.
Pinout Configuration and Description
The MCP3204-BI/SL is available in a 16-pin PDIP, SOIC, or TSSOP package. Understanding its pinout is crucial for correct circuit design.
CH0-CH3 (Pins 1-4): Analog input channels 0 through 3.
VSS / DGND (Pin 5): Digital ground reference.
VREF (Pin 6): Reference voltage input. The analog input voltage range is 0V to VREF. For best performance, use a stable, low-noise voltage source here.
AGND (Pin 7): Analog ground reference. It is often recommended to connect this to the same ground plane as VSS but with a star-point configuration to minimize noise.
VDD (Pin 8): Positive supply voltage (2.7V - 5.5V).
CS/SHDN (Pin 9): Chip Select/Shutdown input. This active-low pin initiates communication with the device when pulled low and ends the conversion cycle when brought high.
DIN (Pin 10): Serial Data Input. The MCU uses this pin to send configuration bits (e.g., start bit, single-ended/diff mode, channel selection) to the ADC.
DOUT (Pin 11): Serial Data Output. The ADC outputs the conversion result, MSB first or LSB first, on this pin.
CLK (Pin 12): Serial Clock input. The MCU generates the clock signal on this pin to synchronize data shifting in and out.
Pins 13-16: No Connection (NC).
Typical Application Circuit Guide
A basic application circuit for interfacing the MCP3204 with an MCU like an Arduino or a PIC microcontroller is straightforward.
Components Required:
Microcontroller (e.g., Arduino Uno)
MCP3204 ADC
Power supply decoupling capacitors (e.g., 100nF ceramic and 10μF electrolytic across VDD and AGND)
A stable voltage reference source (e.g., a 2.5V or 4.096V reference IC for precision, or VDD for less critical applications)
Potentiometer or sensor for analog input
Wiring Connections:
1. Power: Connect VDD to the MCU's 5V or 3.3V rail. Decouple it with a 100nF capacitor to AGND.
2. Ground: Connect both AGND and VSS (DGND) to the MCU's ground.
3. SPI Bus:
Connect the MCU's CS pin to the ADC's CS/SHDN (Pin 9).
Connect the MCU's SCK pin to the ADC's CLK (Pin 12).
Connect the MCU's MOSI pin to the ADC's DIN (Pin 10).
Connect the MCU's MISO pin to the ADC's DOUT (Pin 11).
4. Reference Voltage: Connect VREF (Pin 6) to a clean voltage reference. For simple tests, connecting it to VDD is acceptable.
5. Analog Input: Connect a potentiometer's wiper or a sensor's output to one of the analog input channels, e.g., CH0 (Pin 1). The other terminals of the potentiometer go to VDD and GND.
Software Operation:
The MCU controls the conversion process by:
1. Pulling the CS pin low to activate the ADC.
2. Sending a serial command string over DIN. This string typically includes a start bit, the configuration bits (single-ended mode and channel selection).
3. Clocking the CLK pin to simultaneously read the 12-bit conversion result bit-by-bit from the DOUT pin.
4. Pulling CS high to end the conversion cycle.
ICGOOODFIND: The MCP3204-BI/SL remains a cornerstone component for designers seeking a reliable, 12-bit resolution ADC with multiple input channels. Its simple SPI interface ensures easy integration with virtually any modern microcontroller, making it an excellent choice for industrial control, consumer electronics, and sensor data logging applications where cost-effective precision is paramount.
Keywords: SPI Interface, 12-Bit Resolution, Analog-to-Digital Converter, Data Acquisition, Voltage Reference.
