Microchip MCP3204T-CI/ST 12-Bit 4-Channel ADC: Datasheet, Pinout, and Application Circuit Guide
The Microchip MCP3204T-CI/ST is a 12-bit, 4-channel successive approximation register (SAR) analog-to-digital converter (ADC) that provides a powerful yet cost-effective solution for embedded systems requiring precise analog signal acquisition. Its high resolution and SPI interface make it a popular choice for a wide range of industrial, automotive, and consumer applications. This guide delves into its key specifications, pinout configuration, and a practical application circuit.
Datasheet Overview and Key Specifications
The MCP3204 is a 12-bit resolution ADC, meaning it can resolve an analog input into 4096 (2^12) discrete digital values. This offers a significant improvement over 10-bit ADCs, providing finer granularity for measuring sensors like thermistors, potentiometers, or current sensors.
Key features extracted from the datasheet include:
4 Single-Ended or 2 Pseudo-Differential Input Channels: It offers flexibility in input configuration. The four channels (CH0-CH3) can be used as standard single-ended inputs, or they can be paired to create two differential input channels, which are excellent for rejecting common-mode noise.
SPI Serial Interface (SPI Mode 0,0 and 1,1): It communicates with a microcontroller (MCU) via a simple 4-wire SPI bus (CS, CLK, DIN, DOUT), making it easy to interface with virtually any modern MCU.
100k Samples Per Second: A maximum sample rate of 100 ksps is suitable for many medium-speed applications such as DC voltage monitoring, temperature sensing, and slow-moving data acquisition.
Low Power Consumption: The device operates with a single supply voltage ranging from 2.7V to 5.5V, making it ideal for both 3.3V and 5V systems and battery-powered devices.
Operating Temperature Range: The T-grade version (MCP3204T) is specified for the industrial temperature range of -40°C to +85°C.
Pinout Configuration
The MCP3204T-CI/ST is available in a 16-pin TSSOP package. Understanding its pinout is crucial for correct PCB layout.
Pins 1-4 (CH0-CH3): Analog input Channels 0 through 3.
Pin 5 (VSS/AGND): Analog Ground.
Pin 6 (VREF): Reference Voltage Input. The voltage applied here sets the full-scale range of the ADC. For example, with VREF = 3.3V, 1 LSB = (3.3V / 4096) ≈ 0.8mV.
Pin 7 (VDD/AVCC): Positive Power Supply (2.7V - 5.5V).
Pin 8 (DGND): Digital Ground.
Pin 9 (CS/SHDN): Chip Select/Shutdown Input. Active-low pin used to initiate communication and to put the device in low-power shutdown mode.
Pin 10 (DIN): Serial Data Input from the MCU.
Pin 11 (DOUT): Serial Data Output to the MCU.
Pin 12 (CLK): Serial Clock Input from the MCU.
Pins 13-16: No Connection (NC).
Typical Application Circuit Guide
A basic application circuit for interfacing the MCP3204 with a microcontroller is straightforward. The following components and connections are essential for robust operation:
1. Power Supply Decoupling: Place a 100nF ceramic capacitor and a larger 1-10µF electrolytic or tantalum capacitor as close as possible between the VDD (pin 7) and AGND (pin 5). This is critical for stabilizing the supply voltage and filtering noise.
2. Reference Voltage (VREF): For highest accuracy, use a stable, low-noise voltage reference IC. For less critical applications, VREF can be tied directly to VDD. Decouple VREF with a 100nF capacitor to AGND.
3. Grounding: Connect both AGND (pin 5) and DGND (pin 8) to a common ground plane on the PCB. This helps prevent digital noise from corrupting the analog measurements.
4. SPI Interface: Connect the CS, CLK, DIN, and DOUT pins directly to the corresponding SPI pins on the MCU. If the MCU runs at a different voltage level (e.g., 3.3V MCU with 5V ADC), use level-shifting circuitry.
5. Analog Inputs: The analog inputs should be filtered. A simple RC low-pass filter (e.g., a 1kΩ resistor and a 100nF capacitor to ground) on each channel can effectively suppress high-frequency noise aliasing into the conversion results.
ICGOOODFIND: The MCP3204T-CI/ST stands out as an exceptionally versatile and cost-effective ADC for embedded designers. Its 12-bit resolution, flexible input modes, and simple SPI interface strike a perfect balance between performance and ease of use, making it an excellent choice for adding multi-channel analog sensing capabilities to any project.
Keywords: 12-Bit ADC, SPI Interface, Successive Approximation Register (SAR), Analog-to-Digital Converter, Differential Input.
