Since the manufacturer did not release a "fixed" datasheet, the open-source community (specifically developers working on the Linux Kernel sound/pci/hda tree) had to "fix" the implementation by guessing and testing.
A notable example of this "fix" involves the Coefficient Write Protocol.
The datasheets indicated that you send data to the chip, but they didn't explain the required handshake. Developers discovered that writing to the hidden nodes required a specific sequence involving the SET_COEF_INDEX and PROC_COEF verbs.
The Discovery:
In 2012, developers analyzing the Windows drivers discovered that the CS420x family required specific coefficients to be written to Node 0x11 (the "secret" node) to toggle specific hardware features. For example, to fix the subwoofer output on a MacBook Pro, they found a bit had to be flipped in a coefficient that wasn't listed in any public PDF.
// Example of the "Fix" found in Linux Kernel Source (patch_cirrus.c)
// This sequence was not in the original datasheet
0x11, AC_VERB_SET_COEF_INDEX, 0x0020 , // Unlock the secret register
0x11, AC_VERB_SET_PROC_COEF, 0x0001 , // Enable the specific output path
Without a datasheet, it feels risky. But after "fixing" the driver issues:
| Feature | CX31993 (Fixed) | Apple A2049 (C100) | Realtek ALC5686 | | :--- | :--- | :--- | :--- | | Max Bit Depth | 32-bit | 24-bit | 32-bit | | Max Sample Rate | 384kHz | 48kHz (locked) | 384kHz | | Output Impedance | ~2Ω (very good) | ~0.9Ω (better) | ~10Ω (worse) | | Power Draw | 35mA (fixed) | 25mA | 45mA |
Verdict: A properly fixed CX31993 beats the Apple dongle for high-res listening because the Apple dongle is hardware-capped to 48kHz on Android/Windows unless you use expensive apps.
The "CX31993" datasheet "fix" is a case study in vendor obfuscation. The "better" version of the documentation exists not as a paper manual, but as the collective knowledge base of the Linux audio driver tree. If you have a specific electrical issue with this chip, you may need to trace the schematics of a working device rather than relying on the official documentation.
Finding a formal datasheet for the Synaptics Conexant CX31993
can be difficult as it is often proprietary, but several community resources and technical reviews provide the essential parameters and implementation details needed to "fix" or optimize its performance. Technical Specifications & Performance Based on documentation from manufacturers like Concept Kart
, the chip is a Class G amplifier designed for high-resolution audio over USB-C. DAC Sampling Rate : Up to 32-bit / 384kHz. Signal-to-Noise Ratio (SNR)
: Typically >128dB (chip spec), though implementation results like the JCALLY JM6E report around 117dB. Dynamic Range (DNR) Power Output (Thrust) : Roughly 65mW (often tested at 32Ω). Distortion (THD+N) : ~0.0003% (-95dB). ADC Recording Rate : Supports up to 24-bit / 96kHz for microphone input. Common Implementation & "Fixes"
If you are looking to improve or fix a CX31993-based device, consider these community findings: Noise Filtering : Developers at the Framework Community
have noted high-frequency noise (>200kHz) in some implementations. Since it is a Class G amp, adding a low-pass filter to the output can help clean up ultrasonic artifacts that may interfere with sensitive equipment like oscilloscopes. External Amplification
: While the chip is capable, pairing it with an external Op-Amp (like the
) is a common "better" design found in higher-end dongles like the JCALLY JM6 Pro to increase driving power for high-impedance headphones. Hardware ID : The device typically identifies as
in system logs, which can be useful for driver troubleshooting or firmware patching in Linux/Android environments. Build Quality Issues
: Reviewers often note that while the chip is solid, the thin 8-strand silver-plated wires used in many budget dongles are prone to internal breakage. If your device is cutting out, the "fix" is often resoldering or replacing the fragile cable rather than the chip itself. Community & Documentation Links Any link to the cx31993 datasheet?
Feature: Enhanced Datasheet for CX31993
Description: The goal of this feature is to improve the accuracy, clarity, and usability of the CX31993 datasheet, ensuring that users can easily find and understand the necessary information about this IC. cx31993 datasheet fix better
Requirements:
Benefits:
Acceptance Criteria:
The Conexant CX31993 is a popular high-resolution USB-C DAC/Amp chip known for its neutral-to-bright sound profile and efficient power consumption. Finding an official manufacturer datasheet can be difficult as it is often not publicly available, but the community and retail listings provide comprehensive technical details and "fixes" to maximize its performance. Core Technical Specifications
If you are looking for specific data points for your project or setup, here are the validated specs: Maximum Sampling Rate: 384 kHz / 32-bit. Signal-to-Noise Ratio (SNR): -128dB. Output Voltage: 1V to 2 Vrms (varies by implementation). Power Output: ~65mW at 32Ω.
Output Impedance: Standard designs are ~2Ω, but specialized versions like the JCALLY JM7MAX offer an ultra-low 0.5Ω. Guide to "Fix" and Improve Performance
To get "better" performance out of a CX31993-based device, follow these community-tested optimizations: 1. Bypass Impedance Sensing (Power Boost)
Many CX31993 dongles (like the JM20 or CX-Pro) have an internal "Impedance Sense" mechanism that limits output voltage if it detects low-impedance IEMs to prevent clipping.
The Fix: Plug a high-impedance adapter or just an extension cable into the dongle before plugging the dongle into your phone/PC. Once the device is powered and recognized, plug your actual headphones into the adapter. This can bypass the limit and provide up to double the output power. 2. Manage Treble Sibilance
Users often report that the CX31993 can sound overly bright or "thin" with certain headphones.
The Fix: Use a subtle EQ (Equalizer) to roll off the high frequencies (treble range) if you experience sibilance. Alternatively, pair it with headphones that have a "warm" sound signature to balance the chip's lean tonality. 3. Filter Electrical Noise
If you are integrating the chip into a custom build (like a Framework expansion card), you might notice high-frequency noise (above 200kHz).
The Fix: Implement a Low-Pass Filter in your circuit design to clean up Class G amplifier noise, which has been observed in some oscilloscope tests. 4. Troubleshooting Connection Issues If the device is not recognized or has static: Any link to the cx31993 datasheet? - Facebook
Where to find the ic datasheet and pinout details for SN8P2612? * Kisur Chandro Das ► Repair, Restore or Scrap it Audio and Video. Facebook·ChiFi Audio Reviews Audio Expansion Card - CX31993 Datasheet
Conexant CX31993 is a high-performance, low-power USB Type-C digital-to-analog converter (DAC) chip widely used in portable "dongle" DACs to "fix" or significantly improve the audio output of smartphones and laptops. Key Specifications & Improvements
The CX31993 is often paired with an independent amplifier chip, such as the
, to provide a "better" and more powerful driving force for demanding headphones. According to product listings on and specialty retailers like ConceptKart , its core capabilities include: Hi-Res Audio Support : Maximum sampling rate of 32-bit / 384kHz , allowing for high-definition, lossless playback. High Signal-to-Noise Ratio (SNR) : Delivers an impressive -128dB SNR
, which translates to a "blacker" background with minimal hissing or interference. Power Output : Capable of outputting and delivering roughly Since the manufacturer did not release a "fixed"
of power per channel, making it suitable for both sensitive IEMs and some over-ear headphones. Low Power Consumption
: Designed to draw minimal power from the host device (phone/tablet) while maintaining stable decoding performance. Concept Kart Why it's a "Fix" for Standard Audio
Most built-in headphone jacks (or cheap stock adapters) suffer from "muddy" sound or electrical interference from the device's internal components. The CX31993 "fixes" this by: Bypassing Internal Circuitry
: It handles the digital-to-analog conversion externally, reducing noise. Enhanced Connectivity : Supports full microphone functionality
and volume controls, ensuring you don't lose headset features when upgrading your sound. Physical Build : Many CX31993-based adapters, such as those found on 8-strand silver-plated copper wire
to improve signal conductivity and durability compared to standard plastic cables. Concept Kart Device Compatibility
It is a "plug-and-play" solution compatible with a wide range of devices, including: : iPhone 15 series, iPad Pro/Air (USB-C models). : Samsung Galaxy S-series, Google Pixel. : Windows 10/11 and macOS. Amazon.com for a DIY repair, or are you trying to compare different dongles that use this chip? AUDIOCULAR Conexant CX Pro CX31993 USB-C DAC & Amp
Maximum sampling rate of 384 kHz | Volume adjustments and an equalizer | Signal-to-Noise Ratio (SNR) of -128dB | Output of 2 Vrms. Concept Kart
Title:
Addressing Deficiencies in the CX31993 Datasheet: A Case for a Complete Public Technical Reference
1. Introduction
The CX31993 is a widely adopted USB Type-C audio DAC/controller chip, known for its low power consumption, 32-bit/384kHz capability, and integrated headphone driver. It is found in many dongles and embedded designs. However, publicly available "datasheets" are often fragmented, incomplete, or contain errors. This paper outlines the critical gaps and proposes a corrected, useful specification.
2. Common Issues with Existing CX31993 Documentation
| Issue | Description | |-------|-------------| | Missing Register Map | No public datasheet details the I²C/HID registers for advanced features (e.g., gain control, filter settings, LED control). | | Incorrect Pinout Diagrams | Several community copies show contradictory pin functions for pins 9, 10, and 11 (e.g., VDDIO vs. GPIO). | | Undocumented Modes | Behavior in "firmware-less" vs. "EEPROM configuration" mode is not clearly defined. | | Electrical Typos | Some sources list VDD as 3.3V max, others 5V – critical for design safety. | | Missing Timing Diagrams | No reset timing or I²S slave mode timing constraints are available. |
3. Proposed "Fixed" Datasheet Structure
A corrected datasheet must include:
Pinout Correction Table (example fix):
| Pin | Name | Correct Function |
|-----|------|------------------|
| 9 | GPIO0 | Configurable: LED/HP sense |
| 10 | VDDIO | 1.8V-3.3V (not analog) |
| 11 | TEST | Tie to GND for normal op |
Register Map Excerpt (most needed):
Application Circuit Fixes:
4. How to Obtain or Generate a Better Datasheet
| Method | Effort | Accuracy |
|--------|--------|----------|
| Contact Synaptics (successor) under NDA | High | High |
| Reverse engineer via USB sniffer + Linux lsusb -v | Medium | Medium |
| Community-collated errata (GitHub) | Low | Low-Medium | Without a datasheet, it feels risky
5. Conclusion
Without an official corrected datasheet, designers rely on guesswork and trial. A community-driven "fixed" datasheet—based on actual hardware measurements and USB descriptor analysis—would significantly reduce development time for CX31993-based products. Synaptics should consider releasing a full public datasheet to support the growing USB-C audio ecosystem.
6. Recommended Next Step
Create a living document (e.g., on Hackaday.io or GitHub) titled "CX31993 Errata & Complete Datasheet v1.0" containing:
Finding a complete, official datasheet for the Conexant (Synaptics) CX31993 Go to product viewer dialog for this item.
can be difficult as it is often proprietary or only available to manufacturers. However, based on technical specifications from device manufacturers like JCALLY and Shenzhenaudio, Core Technical Specifications DAC Sampling Rate: Up to 32-bit / 384kHz. ADC Recording Rate: 24-bit / 96kHz.
SNR (Signal-to-Noise Ratio): 117dB to 128dB (depending on implementation). Dynamic Range (DNR): 117dB to >120dB. THD+N (Distortion): -95dB (approx. 0.0003%). Output Power (Thrust): 65mW at 32Ω. Output Impedance: Typically 0.5Ω (ultra-low) to 2Ω. Frequency Response: 20Hz – 20kHz.
Power Consumption: 22.5mA (standby) / 38mA (operating) [approx. based on typical USB-C implementations]. Known "Fixes" & Optimization Tips If your goal is to "fix" or improve a
-based implementation (like a USB dongle), consider these common community solutions:
If you are looking for the official PDF datasheet to build a driver or design a circuit:
The Situation: The Cx31993 is a Conexant (now part of Synaptics) product. Conexant is notoriously restrictive with their documentation. They do not publish datasheets publicly on their website; they require an NDA (Non-Disclosure Agreement) and a business relationship to access technical manuals.
The Fix: You cannot legally download the full, official electrical characteristics datasheet from a public source.
The official (leaked) partial datasheet suggests register 0x06 controls muting during rate switching.
Better Setting: Configure your OS to use the same sample rate across all apps.
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 problem:
Default power sequencing causes audible pops.
The fix:
The datasheet omits the soft-start sequence. Implement this GPIO sequence via MCU or CPLD:
Reverse on shutdown: HP amp off → RESET → DVDD off → AVDD off.
Without this, you get a 200mV pop transient.
Some manufacturers (like JCALLY and Abigail) left a bootloader backdoor. Using a Linux tool called usb-audio-firmware-tools, you can dump the firmware:
sudo ./cx_fw_tool -d 0x10c4 -p 0x8393 -f new_firmware.bin
Note: A "better" community firmware exists that disables the LED blink on sample rate change, saving 5mA of power.