Cx31993 Datasheet Fix Better

Unlike open chips from Texas Instruments or ESS, the CX31993 is a "black box." Because Conexant focuses on OEM contracts (laptop manufacturers like Dell, HP, and Lenovo), they do not publish public datasheets.

The CX31993 has automatic impedance detection (low gain for <30Ω, high gain for >100Ω). Without the datasheet, we cannot manually set gain. However, you can trick it.

If your CX31993 dongle is buzzing, disconnecting, or sounding "thin," a software fix usually exists. Do not throw the dongle away. cx31993 datasheet fix better

| Parameter | Incorrect (bad copies) | Correct Value | |-----------|----------------------|-------------------| | Supply voltage | 5V only | 3.3V – 5V (internal LDO) | | Output power | Unspecified or wrong | Up to 70mW into 32Ω | | SNR | 110dB (understated) | 124dB (A-weighted) | | THD+N | 0.004% | 0.0008% (-102dB) | | Supported sample rates | 32-192kHz | 44.1, 48, 88.2, 96, 176.4, 192, 352.8, 384kHz | | DSD support | "No" or unspecified | DSD64, DSD128, DSD256 (DoP) |

The problem:
Some batches enumerate as “Conexant USB Audio” without a unique PID/VID. Unlike open chips from Texas Instruments or ESS,

The fix:
External EEPROM (AT24C02) at address 0x50 overrides descriptors. Write this block for custom branding:

Offset 0x00: 0x12,0x01,0x00,0x02,0x00,0x00,0x00,0x40,
0xAA,0xBB,0xCC,0xDD,0x00,0x01,0x01,0x02,0x03,0x01

(Where 0xAA/0xBB = VID, 0xCC/0xDD = PID) (Where 0xAA/0xBB = VID, 0xCC/0xDD = PID) No EEPROM

No EEPROM? The chip falls back to default—fine for most uses, but avoid if you need Windows driver matching.