The CM6642 from C-Media Electronics is a low-power, single-chip USB 2.0 High-Speed audio codec with an integrated MCU for flexible USB audio applications. The manufacturer’s Rev.1.0 datasheet identifies headset, headphone, docking, speaker, microphone and related USB audio products among its intended applications.
The device is compliant with USB 1.1/2.0 Full-Speed and USB 2.0 High-Speed operation and supports both USB Audio Class 1.0 and 2.0. Playback and recording support sample rates up to 192kHz with 16-bit or 24-bit audio data.
The CM6642 integrates two DAC channels and three ADC channels, supporting stereo playback together with line, microphone and ANC-related audio capture. It also includes integrated hardware Active Noise Cancellation (ANC) functionality for headset and headphone applications.
An integrated Class-G low-power headphone amplifier provides stereo headphone output. Under the manufacturer’s specified test conditions, typical SNR is approximately 100dB for the DAC, 94dB for the ADC, and 98dB for the headphone output with a 32Ω load.
The chip also incorporates an S/PDIF transmitter for digital audio output at sample rates up to 192kHz and 24-bit resolution, providing an additional digital interface for external audio equipment.
An embedded low-power MCU with 16KB OTP memory supports product configuration and customization. External control interfaces include I²C and SPI, with the documented I²C control interface supporting clock rates up to 400kHz.
Additional integrated functions include GPIOs, PWM LED control, audio jack detection, 4-button headset control, watchdog timer, and automatic OMTP/CTIA headset switching.
The CM6642 supports a crystal-less design and integrates multiple internal power functions to reduce external component count. The recommended USB VBUS supply range is 4.75V to 5.25V, with 5V nominal operation.
Typical current consumption is approximately 33mA during simultaneous playback and recording without load, 59mA with a 32Ω load, and 455µA in USB suspend mode, under the manufacturer’s specified conditions.
The specified ambient operating-temperature range is 0°C to +70°C, with a storage-temperature range of −40°C to +125°C. The device uses an industrial-standard 48-pin QFN package measuring approximately 5 × 6.5mm.
C-Media’s current public USB Audio Codec product list and download center no longer list the CM6642, and the current official site does not expose an Active, NRND, or Obsolete lifecycle designation for this exact device. Therefore, a current production-status claim should not be added without direct confirmation from C-Media.
Key Specifications
- Manufacturer: C-Media Electronics
- Manufacturer Part Number: CM6642
- Device Type: USB Audio Codec
- USB Compliance: USB 1.1 / USB 2.0
- USB Modes: Full-Speed / High-Speed
- USB Audio Class: UAC 1.0 / UAC 2.0
- DAC Channels: 2
- ADC Channels: 3
- Maximum Playback Rate: 192kHz
- Maximum Recording Rate: 192kHz
- Audio Resolution: Up to 24-bit
- Playback Rates: 44.1 / 48 / 96 / 192kHz
- Recording Rates: 44.1 / 48 / 96 / 192kHz
- Typical DAC SNR: 100dB
- Typical ADC SNR: 94dB
- Typical Headphone SNR at 32Ω: 98dB
- Headphone Amplifier: Class-G
- Hardware ANC: Yes
- S/PDIF Transmitter: Yes
- Embedded MCU: Yes
- OTP Memory: 16KB
- I²C: Yes
- I²C Clock: Up to 400kHz
- SPI: Yes
- GPIO: Yes
- PWM LED Driver: Yes
- Jack Detection: Yes
- OMTP / CTIA Auto Switch: Yes
- Headset Button Detection: Yes
- Watchdog Timer: Yes
- Crystal-Less Operation: Supported
- Recommended VBUS: 4.75V to 5.25V
- Typical Active Current: 33mA, Play + Record, No Load
- Typical Active Current: 59mA, 32Ω Load
- Typical Suspend Current: 455µA
- Operating Temperature: 0°C to +70°C
- Storage Temperature: −40°C to +125°C
- Package: QFN-48
- Package Size: 5 × 6.5mm
- Current Lifecycle Status: Not explicitly published on C-Media’s current website
Typical Applications
Suitable for USB headsets, USB headphones, USB microphones, ANC headsets, USB sound cards, docking audio devices, USB speakers, VoIP devices, and mobile or tablet audio accessories.
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