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Introduction: Why the CX31993 Matters In the wake of the smartphone headphone jack removal and the shift toward ultra-thin laptops, the humble USB-C to 3.5mm adapter has become an essential daily driver for millions of users. At the heart of many of the best-performing, budget-friendly dongles lies a specific integrated circuit: the Conexant CX31993 .
For engineers, the design is straightforward: a stable 24MHz clock, clean power decoupling, and careful analog ground routing are all that separates a mediocre dongle from an excellent one. For consumers, look for "CX31993" printed on the chip inside your USB-C adapter—it guarantees you are buying verified performance, not snake oil. The technical data presented here is aggregated from public test measurements (AudioScienceReview, L7Audiolab), reverse engineering efforts, and application notes. For mass production, sign an NDA with Synaptics to obtain the full, official CX31993 datasheet. cx31993 datasheet
Pin 1: VBUS (5V input) Pin 2: GND (Power ground) Pin 3: HP_DET (Headphone detection – detects 3.5mm insertion) Pin 4: MIC_BIAS (Provides 1.8V for electret microphone) Pin 5: MIC_IN (Mono microphone input from TRRS sleeve) Pin 6: AGND (Analog ground) Pin 7: HPOUT_R (Right channel output) Pin 8: HPOUT_L (Left channel output) Pin 9: VCOM (Common mode voltage reference – decoupling cap required) Pin 10: DVDD (Digital core voltage – 1.2V regulated internally) Pin 11: USB_DM (USB Data Minus) Pin 12: USB_DP (USB Data Plus) Pin 13: XTAL_IN (24MHz crystal input) Pin 14: XTAL_OUT (24MHz crystal output) Pin 15: RST_N (Reset – active low) Pin 16: VDDIO (I/O voltage – 3.3V) Introduction: Why the CX31993 Matters In the wake
| Feature | CX31993 | Realtek ALC5686 | Realtek ALC4042 | | :--- | :--- | :--- | :--- | | | 384 kHz | 384 kHz | 96 kHz | | SNR | 124 dB | 120 dB | 104 dB | | THD+N | -93 dB | -95 dB | -85 dB | | Output Power (32Ω) | 30 mW | 33 mW | 40 mW | | DSD Support | DSD128 | DSD128 | No | | Typical Use | Mid-range dongles | High-end dongles | Budget dongles | For consumers, look for "CX31993" printed on the
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