ADCs for portables promise ‘professional’ audio performance

March 05, 2015 // By Graham Prophet
TI’s multichannel devices simplify audio front-end design while reducing standby power consumption; a family of six high-performance audio ADCs has dynamic range as high as 110 dB.

Devices in the PCM1865 family integrate features typically found in portable audio codecs, while also giving designers a level of performance previously found only in single-function, professional audio ADCs, TI asserts.

Powered by a single 3.3V supply, the PCM1865 audio ADC removes the traditional requirement for a dedicated analogue 5V rail. Each device in the family solves system-level design issues, including hum and ground noise, input-signal level sensitivity, and attenuation, all with a single device. Use them TI suggests, in personal computers; sound bars; audio docks; Bluetooth speakers; video-security systems; and automotive infotainment equipment including after-market head units, amplifiers and active noise-cancellation systems.

The PCM1865 family consists of six pin-to-pin compatible devices offering two- and four-channel options, with software- and hardware-controlled variants. Three of the six devices in the PCM1865 family can achieve up to 110 dB dynamic range performance. No other audio ADCs on the market can achieve a performance level of 110 dB with a single 3.3-V power supply, TI says.

With direct, high-voltage 2.1 Vrms support, the devices aim to deliver best audio quality with a higher SNR. Software-controlled automatic clipping-suppression helps designers optimise input sensitivity for maximum SNR.

The new audio ADCs can eliminate as many as 20 components with no loss of performance. The devices integrate a clock-generating phase-locked loop (PLL), programmable gain amplifier and universal front end, which supports various inputs from low-level microphones to 4.2 Vrms differential inputs. Designers can configure single-ended and differential inputs to cancel hum and ground noise.

The integration of TI’s Energysense technology helps designers meet operating requirements set by the EU Ecodesign Directive. By using the on-chip secondary ADC, designers can set both sleep and wake-up thresholds, which can help equipment achieve the energy efficiency levels required. The parts occupy 7.8 by 4.4 mm 30-pin TSSOP packages.

Evaluation modules (EVMs) include the PCM1865EVM, at $149.