ADAU1977:  Quad ADC with Diagnostics

The ADAU1977 incorporates four high performance analog-todigital converters (ADCs) with direct-coupled inputs capable of 10 V rms. The ADC uses multibit sigma-delta (Σ-Δ) architecture with continuous time front end for low EMI. The ADCs can be connected to the electret microphone (ECM) directly and provide the bias for powering the microphone. Built-in diagnostic circuitry detects faults on input lines and includes comprehensive diagnostics for faults on microphone inputs. The faults reported are short to battery, short to microphone bias, short to ground, short between positive and negative input pins, and open input terminals. In addition, each diagnostic fault is available as an IRQ flag for ease in system design. An I2C/SPI control port is also included. The ADAU1977 uses only a single 3.3 V supply. The part internally generates the microphone bias voltage. The microphone bias is programmable in a few steps from 5 V to 9 V. The low power architecture reduces the power consumption. An on-chip PLL can derive the master clock from an external clock input or frame clock (sample rate clock). When fed with a frame clock, the PLL eliminates the need for a separate high frequency master clock in the system. The ADAU1977 is available in a 40-lead LFCSP package.

• Automotive audio systems
• Active Noise Cancellation System