CMX638L4

Telecom Overview

The CMX638L4 is a full-duplex RALCWI Vocoder with an integrated voice CODEC, operating from dual power supplies of 1.8V and 3.3V tolerant I/O. It supports multiple bit rate modes including 2400 bps, 2750 bps, and 3600 bps with Forward Error Correction (FEC). The device utilizes a 4-bit Viterbi soft decision decoder and accommodates packet lengths of 20ms, 40ms, 60ms, and 80ms. It features ancillary audio functions such as Voice Activity Detection (VAD), Comfort Noise Generation (CNG), and DTMF tone regeneration. The component is housed in a 48-pin LQFP package.

Telecom Feature Summary

• Full-duplex vocoding capability with integrated voice CODEC for analogue-to-digital conversion
• RALCWI coding algorithm providing near toll quality voice at low bit rates
• Integrated Forward Error Correction (FEC) engine with 4-bit Viterbi soft decision decoding
• Support for multiple packet lengths and ancillary audio functions like DTMF regeneration

Telecom Applications

• Digital PMR, LMR, and Voice Radio systems
• DMR TDMA and FDMA digital trunking protocols
• Digital WLL and voice scrambling applications
• Voice storage, playback, and regenerative repeater systems

Telecom Procurement Notes

Verify the specific ordering suffix 'L4' to confirm the 48-pin LQFP package configuration against the manufacturer's official documentation. Ensure that the required 1.8V and 3.3V power supply rails are compatible with the target system design before procurement.

Telecom Selection Notes

Select the CMX638L4 when full-duplex operation and an integrated voice CODEC are required. This model differs from the half-duplex CMX608/CMX618 variants by supporting simultaneous encoding and decoding. Verify that the host system can support the C-BUS interface for configuration and control.

Telecom Part Context

The CMX638L4 belongs to the CMX608/CMX618/CMX638 family of RALCWI Vocoders manufactured by CML Microcircuits. While the CMX608 requires an external CODEC and operates in half-duplex mode, the CMX638 integrates the CODEC and supports full-duplex communication. The 'L4' designation specifically identifies the 48-lead Low Profile Quad Flat Package variant within this product line.

Telecom Replacement Considerations

Publicly confirmed substitute part numbers for the CMX638L4 are not available in the provided source material.