How to Use PCM1808: Examples, Pinouts, and Specs

The PCM1808 is a 24-bit audio analog-to-digital converter (ADC) designed for high-performance audio applications. It converts analog audio signals into digital data with exceptional precision, offering low distortion and a high dynamic range. This makes it an ideal choice for professional audio equipment, consumer electronics, and other audio processing systems.

• Professional audio recording equipment
• Consumer audio devices (e.g., home theater systems, audio interfaces)
• Digital signal processing (DSP) systems
• Musical instruments with digital output
• Audio measurement and analysis tools

The PCM1808 is a highly capable ADC with the following key technical specifications:

The PCM1808 is housed in a 14-pin TSSOP package. Below is the pin configuration and description:

1. Power Supply: Connect the analog power supply (VCC) and digital power supply (VDD) to a stable 3.3 V source. Ensure proper decoupling capacitors are placed near the power pins to minimize noise.
2. Grounding: Connect AGND and DGND to a common ground plane to avoid ground loops.
3. Analog Inputs: Feed the left and right analog audio signals into the VINL and VINR pins, respectively. Use appropriate coupling capacitors to block DC components.
4. Clock Signals: Provide a system clock signal (SCKI) and configure the bit clock (BCK) and word clock (LRCK) according to the desired audio format and sampling rate.
5. Audio Data Output: The digital audio data is output through the DOUT pin. Connect this pin to the input of a microcontroller, DSP, or other digital audio processing system.
6. Data Format Selection: Use the FORMAT pin to select the desired audio data format (e.g., I2S or left-justified).
7. Power-Down Control: Use the PDWN pin to enable or disable the device. Pull this pin low to enter power-down mode.

• Clock Synchronization: Ensure that the system clock (SCKI), bit clock (BCK), and word clock (LRCK) are synchronized to avoid data errors.
• Input Signal Conditioning: Use anti-aliasing filters on the analog inputs to prevent high-frequency noise from affecting the ADC performance.
• PCB Layout: Keep analog and digital traces separate to minimize interference. Place decoupling capacitors as close as possible to the power pins.
• Startup Sequence: Apply power to the analog and digital supplies simultaneously to ensure proper initialization.

The PCM1808 can be interfaced with an Arduino UNO to process audio signals. Below is an example of how to configure the Arduino to read audio data from the PCM1808:

#include <SPI.h>

// Define PCM1808 pins connected to Arduino
#define BCK_PIN 3    // Bit clock input
#define LRCK_PIN 4   // Word clock input
#define DOUT_PIN 5   // Digital audio data output

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);

  // Configure PCM1808 pins as inputs
  pinMode(BCK_PIN, INPUT);
  pinMode(LRCK_PIN, INPUT);
  pinMode(DOUT_PIN, INPUT);

  Serial.println("PCM1808 Audio ADC Initialized");
}

void loop() {
  // Read audio data from PCM1808
  int audioData = digitalRead(DOUT_PIN);

  // Print the audio data to the serial monitor
  Serial.println(audioData);

  // Add a small delay to simulate processing
  delay(1);
}

Note: The above code is a basic example for demonstration purposes. In a real application, you would need to implement proper clock synchronization and data handling for accurate audio processing.

1. No Output from DOUT Pin

   • Cause: Missing or incorrect clock signals (SCKI, BCK, LRCK).
   • Solution: Verify that the clock signals are present and properly synchronized.

2. Distorted Audio Output

   • Cause: Incorrect input signal levels or missing anti-aliasing filters.
   • Solution: Ensure the input signal is within the specified range (0.6 V RMS) and use appropriate filters.

3. Device Not Powering On

   • Cause: Incorrect power supply connections or insufficient decoupling.
   • Solution: Check the power supply connections and add decoupling capacitors near the power pins.

4. High Noise in Output

   • Cause: Poor PCB layout or interference between analog and digital signals.
   • Solution: Separate analog and digital traces and use a solid ground plane.

Q: Can the PCM1808 operate at 5 V?
A: No, the PCM1808 is designed to operate at 3.3 V for both analog and digital power supplies.

Q: What audio formats does the PCM1808 support?
A: The PCM1808 supports I2S and left-justified audio data formats, selectable via the FORMAT pin.

Q: Is an external clock source required?
A: Yes, the PCM1808 requires an external system clock (SCKI) for operation. Ensure the clock frequency matches the desired sampling rate.

Q: Can the PCM1808 be used for mono audio?
A: Yes, you can use only one of the analog input channels (VINL or VINR) for mono audio applications.