The ADAU1977 integrates four high-performance analog-to-digital converters (ADCs) with direct coupled inputs up to 10 V RMS. ADC uses multi-bit sigma-delta (σ-Delta) architecture with front-end continuous time to achieve low EMI. The adc can be connected directly to the electret microphone (ECM) and provide a bias for the microphone power supply. Built-in diagnostic circuit detects input line faults, including full diagnosis of microphone input faults.
Function block diagram
The reported faults include short battery, short microphone offset, short ground, short positive and negative input pins, and disconnected input terminals. In addition, each diagnostic failure can be used as an IRQ flag to facilitate system design. i2c /SPI control ports are also included. The ADAU1977 uses only a 3.3V power supply. A microphone bias voltage is generated within the component.
Microphone bias is programmable in several steps, from 5v to 9v. Low power architecture to reduce power consumption. The on-chip PLL can obtain the master clock from the external clock input or from the frame clock (sample rate clock). PLL eliminates the need for a separate high frequency master clock in the system when the frame clock is input. The ADAU1977 comes in a 40-pin LFCSP package.
