These capacitors must be placed within 1.5mm of the VREF pin, grounding directly to a solid, uninterrupted analog ground plane (AGND). This suppresses high-frequency switching noise from the internal charge pump.
This sequence ensures that the internal reference and clock are ready before the analog front-end is configured, preventing many common initialization failures.
Because the Cx31993 is often implemented in "no-name" or ultra-budget hardware, users and developers frequently encounter the following issues and documented solutions: Conexant (CX-Pro) CX31993 USB-C Amp/DAC Review Cx31993 Datasheet Fix
Avoid generic Windows USB Audio Class (UAC2) drivers if you experience clicking sounds. Look for Realtek/Conexant composite drivers or use ASIO4ALL to enforce clean, low-latency playback.
The official Conexant engineering brief provides a bare-minimum reference design. It often omits the robust protection and filtration networks required for real-world USB environments. Below are the critical engineering modifications required to correct these design oversights. These capacitors must be placed within 1
This is triggered by an incorrect descriptor value in the chip's default USB Endpoint Descriptor endpoint configuration. Flash the EEPROM to modify the bmAttributes byte from 0x01 (Asynchronous) to 0x02 (Adaptive), or use an external tool like UAC2 Control Panel to override host-side driver caching. 4. Optimized Reference Schematic Checklist
Install a 5.1V TVS diode on the VBUS line right at the USB-C connector entrance to clamp voltage transients. Impedance Matching Because the Cx31993 is often implemented in "no-name"
Note: If you meant a different component (e.g., CX20993, CX31983, or a generic Chinese USB DAC dongle), the approach remains similar — verify pinout and power sequencing.
Are you , or are you trying to repair an existing commercial dongle ?
If you are experiencing low volume, persistent background hiss, sudden disconnects, or hardware recognition errors, you do not have a broken chip. You likely have a configuration error. This comprehensive guide outlines the critical hardware and software fixes required to optimize the CX31993 platform. 1. Hardware Fixes: Correcting Circuit Board Anomalies
Since you can't just download a PDF, you have to rely on community reverse-engineering and teardowns of existing products, like the Audio Expansion Card 2. Technical Specs (The Essentials)