Microchip MCP3004T-I/ST 4-Channel 10-Bit ADC: Datasheet, Pinout, and Application Circuit Guide
The MCP3004T-I/ST from Microchip Technology is a 10-bit resolution, successive approximation register (SAR) analog-to-digital converter (ADC) that provides a simple and cost-effective solution for adding analog sensing capabilities to digital systems. This IC is particularly popular in embedded systems, including those using microcontrollers like Arduino and Raspberry Pi, for tasks ranging from environmental monitoring to industrial control. This guide explores its key specifications, pinout, and a fundamental application circuit.
Datasheet Overview and Key Specifications
The MCP3004 is a 4-channel single-ended or 2-channel pseudo-differential ADC. It communicates via a serial peripheral interface (SPI), making it easy to interface with most microcontrollers using only a few digital I/O pins.
Key specifications from the datasheet include:
Resolution: 10-bit, providing 1024 (2¹⁰) discrete digital output codes.
Channels: 4 single-ended or 2 pseudo-differential input channels.
Supply Voltage: Operates from a single 2.7V to 5.5V power supply, compatible with both 3.3V and 5V logic.
Conversion Rate: Up to 200 kilosamples per second (ksps) at 5V.
Interface: SPI serial interface (supports modes 0,0 and 1,1).
Package: The "T-I/ST" suffix denotes it comes in a TSSOP-14 package and is rated for the industrial temperature range (-40°C to +85°C).
Pinout Configuration
Understanding the pinout is crucial for correct circuit design. The MCP3004T-I/ST comes in a 14-pin TSSOP package.
Pins 1-4 (CH0-CH3): Analog Input Channels 0 through 3. These are used for the four single-ended inputs.
Pin 5 (VREF): Voltage Reference Input. This pin sets the analog-to-digital conversion range. For example, if VREF is 3.3V, an input of 3.3V will result in a digital output of 1023.
Pin 6 (AGND): Analog Ground. The ground reference for the analog circuitry.
Pin 7 (CLK): Serial Clock (SPI Clock). This pin is driven by the microcontroller to clock the data in and out.
Pin 8 (DOUT): Serial Data Output (SPI MISO). The ADC sends conversion data to the microcontroller on this pin.
Pin 9 (DIN): Serial Data Input (SPI MOSI). The microcontroller sends control commands (starting the conversion and selecting the channel) on this pin.
Pin 10 (CS/SHDN): Chip Select/Shutdown Input (SPI SS). This active-low pin is used to enable the device and begin a communication cycle.
Pin 11 (DGND): Digital Ground.
Pin 12 (VDD): Digital Power Supply (2.7V - 5.5V).
Pins 13 & 14: Not connected (N/C).
Basic Application Circuit Guide
A typical connection circuit for a microcontroller (e.g., an Arduino) is straightforward. The following steps outline a standard single-ended configuration.
Components Needed:
Microcontroller (Arduino Uno)
MCP3004T-I/ST ADC
Potentiometer (for testing) or any analog sensor (e.g., LDR, thermistor)
Breadboard and jumper wires
0.1µF decoupling capacitor (placed between VDD and AGND)
Wiring Connections:
1. Power:
Connect the ADC's VDD (Pin 12) to the microcontroller's 5V or 3.3V rail.
Connect both AGND (Pin 6) and DGND (Pin 11) to the microcontroller's GND.
Place a 0.1µF ceramic capacitor close to the ADC between VDD and AGND to filter noise.
2. SPI Communication:
CLK (Pin 7) → Arduino digital Pin 13 (SCK)
DOUT (Pin 8) → Arduino digital Pin 12 (MISO)
DIN (Pin 9) → Arduino digital Pin 11 (MOSI)
CS/SHDN (Pin 10) → Arduino digital Pin 10 (Any digital pin can be used as Chip Select)
3. Analog Input and Reference:
Connect the wiper of a potentiometer (with the other legs to VDD and GND) to CH0 (Pin 1).
Connect VREF (Pin 5) to the same VDD rail to use the supply voltage as the reference. For more precise readings, connect VREF to a stable voltage reference IC.
Software Consideration: The microcontroller must generate the correct SPI sequence to initiate a conversion and read the 10-bit result. Most platforms, including Arduino, have libraries (e.g., the `MCP3XXX` library) that simplify reading values from the MCP3004.
The MCP3004T-I/ST is an exceptionally versatile and easy-to-use ADC, making it an ideal choice for hobbyists and professionals alike. Its SPI interface minimizes wiring, and its wide operating voltage range ensures broad compatibility. Whether you're reading sensors, measuring voltages, or adding analog inputs to a Raspberry Pi, the MCP3004 provides a reliable and straightforward solution, solidifying its status as a go-to component in the embedded designer's toolkit.
Keywords: MCP3004, 10-bit ADC, SPI Interface, Analog-to-Digital Converter, Sensor Interfacing
