Cx31993 Datasheet Fix

Conexant (Synaptics) does not distribute public drivers for the CX31993 because it relies on the operating system’s built-in UAC2 (USB Audio Class 2) driver. This is a feature, not a bug. The chip is designed to be plug-and-play.

If a website claims to offer “CX31993 official drivers,” it is almost certainly malware. The only Microsoft-signed driver available is the inbox usbaudio2.sys (dated 2019 or later). A “datasheet fix” that involves downloading an executable is a scam. Cx31993 Datasheet Fix

The Conexant CX31993 has become a ubiquitous entry-level USB audio codec, found in dozens of affordable USB-C to 3.5mm dongles. However, for months, the publicly available datasheets were either incomplete, contained conflicting pinout information, or lacked critical register maps for I²C control. Enter the unofficial “CX31993 Datasheet Fix” – a community-sourced, annotated correction document that has quietly saved hundreds of hobbyist projects. Conexant (Synaptics) does not distribute public drivers for

| Original Datasheet Claim | Corrected Information (Fix v2.1) | Impact | |--------------------------|----------------------------------|---------| | I²C slave address 0x22 | 0x20 (7-bit) | Without this, register writes silently fail. | | Pin 11 = “RESERVED” | GPIO1 (active-low headphone detect) | Enables auto switch between speaker and headphone. | | Max HP output = 1.0Vrms | 1.24Vrms (into 32Ω) | Explains why some dongles measure higher THD at “max volume.” | | Missing register 0x0F | DAC de-emphasis control | Critical for 44.1 kHz linearity. | ASIO4ALL acts as a buffer manager.

The document also includes a verified register dump from a working Tenhz T4 dongle, serving as a golden reference.

If you use music production software (Ableton, FL Studio) and experience dropouts, install a third-party ASIO wrapper:

The CX31993’s native driver (Microsoft’s inbox driver) has poor low-latency performance; ASIO4ALL acts as a buffer manager.