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 high-resolution digital data, ensuring low distortion and high dynamic range. This makes the PCM1808 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 audio processing systems
• Musical instruments with digital output
• Voice recognition systems

The PCM1808 is a highly efficient ADC with the following key technical details:

• Resolution: 24-bit
• Sampling Rate: Supports up to 96 kHz
• Dynamic Range: 99 dB (typical)
• Total Harmonic Distortion (THD+N): -93 dB (typical)
• Input Voltage Range: 0.6 Vpp to 2.1 Vpp (differential)
• Power Supply Voltage:
  • Analog: 5 V
  • Digital: 3.3 V
• Power Consumption: 20 mW (typical)
• Interface: I²S (Inter-IC Sound) or Left-Justified Serial Audio Data
• Package: 14-pin TSSOP (Thin Shrink Small Outline Package)

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

The PCM1808 is straightforward to use in audio applications. Below are the steps and considerations for integrating it into a circuit:

1. Power Supply:
   • Connect the analog power supply (5 V) to the VCC pin and the digital power supply (3.3 V) to the VDD pin.
   • Ensure proper decoupling capacitors are placed near the power supply pins to reduce noise.
2. Analog Inputs:
   • Connect the left and right analog audio signals to the VINL and VINR pins, respectively.
   • Use differential input signals for optimal performance.
3. Clock Signals:
   • Provide a system clock (SCKI) to the PCM1808. A typical clock frequency is 256x, 384x, or 512x the sampling rate.
   • Connect the bit clock (BCK) and left-right clock (LRCK) to synchronize the audio data.
4. Audio Data Output:
   • The digital audio data is output through the DOUT pin in the selected format (I²S or Left-Justified).
   • Use the FORMAT pin to configure the desired audio data format.
5. Reference and Ground:
   • Connect the VREF1, VREF2, and VCOM pins to appropriate decoupling capacitors as specified in the datasheet.
   • Ensure proper grounding by connecting AGND and DGND to a common ground plane.

• Use high-quality capacitors for decoupling to minimize noise and interference.
• Ensure the system clock (SCKI) is stable and within the specified frequency range.
• Avoid long traces for analog input signals to reduce noise pickup.
• Match the impedance of differential input signals for optimal performance.
• If using an Arduino or microcontroller, ensure it supports I²S or Left-Justified audio data formats.

The PCM1808 can be interfaced with an Arduino UNO using an I²S-compatible module (e.g., I²S breakout board). Below is an example code snippet for reading audio data:

#include <I2S.h> // Include the I2S library for Arduino

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

  // Start the I2S interface in receiver mode
  if (!I2S.begin(I2S_PHILIPS_MODE, 44100)) {
    Serial.println("Failed to initialize I2S!");
    while (1); // Halt if initialization fails
  }
  Serial.println("I2S initialized successfully.");
}

void loop() {
  // Check if audio data is available
  if (I2S.available()) {
    int sample = I2S.read(); // Read a 32-bit audio sample
    Serial.println(sample);  // Print the sample to the serial monitor
  }
}

Note: The Arduino UNO does not natively support I²S. Use an external I²S module or a microcontroller with built-in I²S support (e.g., ESP32).

1. No Audio Output:

   • Ensure the system clock (SCKI) is connected and operating at the correct frequency.
   • Verify that the analog input signals are within the specified voltage range.
   • Check the connections for the bit clock (BCK) and left-right clock (LRCK).

2. Distorted Audio:

   • Verify that the differential input signals are properly matched and free of noise.
   • Ensure the decoupling capacitors are correctly placed and of the recommended value.

3. No Data on DOUT Pin:

   • Confirm that the FORMAT pin is set to the correct audio data format.
   • Check the power supply voltages (VCC and VDD) and ensure they are stable.

4. High Noise or Interference:

   • Use a proper ground plane and minimize the length of analog signal traces.
   • Shield the analog input signals if operating in a noisy environment.

Q1: Can the PCM1808 operate with a single-ended input?
A1: No, the PCM1808 is designed for differential input signals. Single-ended inputs may result in degraded performance.

Q2: What is the maximum sampling rate supported by the PCM1808?
A2: The PCM1808 supports a maximum sampling rate of 96 kHz.

Q3: Can I use the PCM1808 with a 3.3 V analog power supply?
A3: No, the analog power supply (VCC) must be 5 V. The digital power supply (VDD) operates at 3.3 V.

Q4: How do I select between I²S and Left-Justified formats?
A4: Use the FORMAT pin to select the desired format. Refer to the datasheet for the specific pin configuration.

Q5: Is the PCM1808 suitable for battery-powered devices?
A5: Yes, the PCM1808 has low power consumption (20 mW typical), making it suitable for battery-powered applications.