Before reaching for a soldering iron, confirm the cause.
Analysis of the CX31993 DAC Chip: Addressing the “Fix Hot” Phenomenon and Datasheet Gaps
| Parameter | Value | Implication | |-----------|-------|--------------| | Supply Voltage (VDD) | 3.0V – 3.6V (Typ. 3.3V) | Exceeding 3.6V causes excess current draw → heat | | Core Current (Icore) | 18 mA (typical) | Baseline power ~60mW | | Headphone Amp Current (Ihp) | Up to 35 mA per channel | Total chip current can reach 88 mA | | Max Junction Temp (Tj) | 125°C | Case temp of 70°C+ indicates internal issues | | Thermal Resistance (θja) | 52 °C/W (QFN package) | Without PCB heatsinking, temp rises ~5°C per 10mW over spec |
This paper establishes that the actual thermal resistance in standard application environments is approximately 95°C/W. The proposed datasheet fix—updating thermal tables and including realistic power derating guidelines—will mitigate the "hot" issues, ensuring the CX31993 operates within safe thermal limits and maintains the audio fidelity for which it was designed. Manufacturers are urged to release Technical Bulletin TB-CX31993-THRM immediately to prevent further field failures.
Before reaching for a soldering iron, confirm the cause.
Analysis of the CX31993 DAC Chip: Addressing the “Fix Hot” Phenomenon and Datasheet Gaps
| Parameter | Value | Implication | |-----------|-------|--------------| | Supply Voltage (VDD) | 3.0V – 3.6V (Typ. 3.3V) | Exceeding 3.6V causes excess current draw → heat | | Core Current (Icore) | 18 mA (typical) | Baseline power ~60mW | | Headphone Amp Current (Ihp) | Up to 35 mA per channel | Total chip current can reach 88 mA | | Max Junction Temp (Tj) | 125°C | Case temp of 70°C+ indicates internal issues | | Thermal Resistance (θja) | 52 °C/W (QFN package) | Without PCB heatsinking, temp rises ~5°C per 10mW over spec |
This paper establishes that the actual thermal resistance in standard application environments is approximately 95°C/W. The proposed datasheet fix—updating thermal tables and including realistic power derating guidelines—will mitigate the "hot" issues, ensuring the CX31993 operates within safe thermal limits and maintains the audio fidelity for which it was designed. Manufacturers are urged to release Technical Bulletin TB-CX31993-THRM immediately to prevent further field failures.