A/D Converter Has Built-In USB Interface For Microphones

In addition to a high-performance 16-bit a/d converter, all of the functions essential for a Universal Serial Bus (USB) microphone are realized on the single-chip AK5370. These include a USB transceiver, a programmable gain amplifier (PGA) controllable-from-the-host USB audio class command processing circuits, a FIFO for isochronous transfer, and mic-bias control circuit. As a result of the high level of integration, there is no need for an external ROM or microprocessor, reducing the number of external components and the area required for installation.
The PGA is controllable from the host over a range of +20 dB to -58 dB in 1 dB steps. The device also has mute/volume and sampling frequency controls, as well as an AGC pin for external control. It supports five sampling frequencies: 8 kHz, 1.025 kHz, 22.05 kHz, 44.1 kHz and 48 kHz. Other features include a pre-amp, bias control circuit, and 3.3V operation. In a 24-pin VSOP package, pricing is $5.51 each/10K.