The PCM2912A is an audio codec with USB connection capability and an analog front-end for headset applications.

The PCM2912A is a bus-powered device that uses the USB voltage source. The PCM2912A meets the requirements of USB2.0 standard connection. This device has analog and digital inputs and outputs; it has a digital USB interface for input and output data; the analog input is directly routed to the A/D converter and to the analog output. 

The microphone input has an optional mic amp with fixed +20 dB. The PCM2912A has 2 digitaloutput flags that can be used as LED indicators for Playback and Record. The PCM2912A requires a 12-MHz clock; it can be provided by an external clock or generated by a built-in crystal resonator.

The PCM2912A requires a 6-MHz (±500 ppm) clock for USB function and audio function, which can be generated from a built-in crystal oscillator with a 6-MHz crystal resonator. 

The 6-MHz crystal resonator must be connected to XTI (pin 8) and XTO (pin 7) with one high (1-MΩ) resistor and two small capacitors, whose capacitance depends on the load capacitance of the crystal resonator. 

An external clock can be supplied through XTI; if an external clock is supplied, XTO must be left open. Because there is no clock disabling signal, using the external clock supply is not recommended. SSPND (pin 29) is unable to use clock disabling.

The PCM2912A has an internal power-on-reset circuit, which works automatically when VBUS (pin 2) exceeds 2.5 V, typical (2.2 V to 2.7 V), and approximately 700 μs is required until the internal reset is released.

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