If necessary, use an external heat sink. The datasheet or application notes might provide guidance on selecting an appropriate heat sink.
~117 dB to 124 dB (depending on implementation). Total Harmonic Distortion (THD+N): -95dB.
Before we fix the heat, we must determine if your unit is faulty or functioning within spec.
To fix the thermal issues of the CX31993, we must first look at its architecture and deployment environment, which explains why it generates noticeable heat. 1. High-Performance Audio Processing
The reference design ties analog and digital grounds through a ferrite bead, but cheap dongles omit this. High-frequency switching noise from the USB bus leaks into the analog output, adding a 2–3dB rise in perceived treble roughness above 8kHz. cx31993 datasheet fix hot
The Conexant (now Synaptics) CX31993 is one of the most popular USB-C DAC chips on the market. It powers countless budget audiophile dongles, delivering impressive 32-bit/384kHz audio at a fraction of the cost of high-end setups. However, many DIY builders, audio engineers, and everyday users notice a common issue:
The datasheet explicitly states: "An external LDO with ripple < 50mV is recommended." Yet many budget dongles connect VBUS (5V nominal, often 5.25V) directly to the chip via a simple resistor divider or no regulator at all. forces internal ESD clamps and regulators into saturation, dissipating excess voltage as heat.
The CX31993 requires a 1.8V digital core and a 3.3V analog supply. Most dongles use a cheap LDO (Low Dropout Regulator) to step down USB’s 5V to these voltages. If the LDO is inefficient (e.g., a 1117 clone), it burns off 1.7V as pure heat before the power even reaches the DAC. This is the primary culprit.
So, why is your dongle hitting 45°C (113°F)? If necessary, use an external heat sink
If you are building a custom board, ensure there is a thermal pad or copper pour connected to the ground pins of the CX31993 to act as a heatsink. Community Post Draft Title: 🚀 CX31993 DAC: The Specs & The "Heat" Fix
Article last updated: 2025. All modifications are at your own risk. Use proper ESD protection and soldering techniques.
For detailed specifications, pinouts, and application notes, it's best to consult the official datasheet from the manufacturer or a reputable distributor. You can try searching on:
The measured thermal resistance ($R_\theta JA$) was found to be , nearly three times the value stated in the datasheet. The datasheet value was likely derived using a high-conductivity JEDEC test board with generous copper spreading, which is physically impossible in the compact form factors where the CX31993 is typically deployed. Total Harmonic Distortion (THD+N): -95dB
The CX31993 is a high-performance, low-power USB Type-C audio SoC often used in budget "dongle" DACs. Up to 32-bit / 384kHz. Signal-to-Noise Ratio (SNR): 128dB. Dynamic Range: 120dB. Output Power: ~65mW into 32Ω.
The CX31993 datasheet specifies internal Low Dropout (LDO) regulators to step down the 5V USB power to 3.3V and 1.2V for the digital core. Linear regulators dissipate excess voltage entirely as heat.
If you plan on driving bigger headphones, look specifically for dongles labeled "CX31993 + MAX97220" . These units pair the CX31993 DAC chip with a Maxim MAX97220 standalone amplifier chip. This raises the power output to about 125mW–140mW, successfully bridging the gap for harder-to-drive gear.