SDAA313A March   2026  – May 2026 INA1650-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Automotive Hi-Fi Headphone Audio System Overview
    1. 2.1 Key Technical Specifications of Automotive Hi-Fi Audio Systems
    2. 2.2 Design Requirements for Automotive Hi-Fi Headphone Audio Systems
  6. 3Automotive Hi-Fi Headphone Audio System Working Principle and Circuit Design
    1. 3.1 DAC Circuit Design
    2. 3.2 Differential-to-Single-Ended Circuit Design
  7. 4Simulation
    1. 4.1 Transient Response Simulation
    2. 4.2 Noise Analysis
    3. 4.3 Power Consumption Simulation and Thermal Calculation
  8. 5Experimental Test
  9. 6Summary
  10. 7References
  11. 8Revision History

2 Automotive Hi-Fi Headphone Audio System Overview

Hi-Fi, short for High-Fidelity, refers to the playback of sound with high-quality reproduction or maximum fidelity to the original audio source. Ideally, Hi-Fi audio devices can achieve ultra-low noise and distortion that are imperceptible to the human ear. As illustrated in Figure 2-1 , the block diagram of a typical Hi-Fi audio system, the Hi-Fi device converts the differential output voltage of a Digital-to-Analog Converter (DAC) into a single-ended voltage capable of driving low-impedance headphones. A differential-to-single-ended converter is employed to convert differential signals into single-ended signals for headphone driving.

Block Diagram of Automotive Hi-Fi Audio System Figure 2-1 Block Diagram of Automotive Hi-Fi Audio System

Most of consumer-grade headphones are single-ended designs (3.5mm/6.35mm interface, requiring only one signal path + ground wire). For single-ended mode, there are AC-coupled and DC-coupled modes. But the single ended DC-coupled mode will contain a DC common mode voltage. This results in high power consumption, and hence DC-coupled single ended mode is not recommended. The single ended AC-coupled mode is better designed for headphone applications. When operating in single-ended AC-coupled mode, the AC-coupling capacitor requires careful selection. This capacitor forms a high-pass filter with the load, and its value has a significant impact on the audio frequency response. A smaller value capacitor will attenuate lower audio frequencies, resulting in a loss of bass response. For this reason a large AC-coupling capacitor is required to block the DC bias from the DAC output while preserving the desired audio frequency range.

Equation 1. F C = 1 2 × 3.14 × C × Z l o a d
DC-Coupled Differential Mic Input Hardware Design Figure 2-2 DC-Coupled Differential Mic Input Hardware Design

For headphone/headset (32Ω) applications: Use ≥470µF to maintain fc = 10Hz.