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Designing and building a USB sound card longer a head ache got the PCM 2702 integrated circuit from Texas Instruments. The PCM2702 is an integrated bit digital to analog converter that has digital to analog output channels. The integrated interface controller of PCM2702 is compliant to the USB .0 standards. The IC handle sampling rates of KHz, 44.1 KHz and KHz. The IC of helpful like on-chip clock generator, digital attenuator, play back flag, suspend flag, zero flag, mute etc. is that this circuit is plug & play and doesn’t any driver software for Windows XP and Windows Vista operating systems.



The circuit gets and audio from the USB through the D+ and D- pins of the PCM2702 all transferring is at full speed. The decoded audio signals at the VOUTL and VOUTR pins of the IC. The 12MHz crystal is connected between the XT0 and XT1 pins of the IC. The VBUS (USB bus power) pin and DGND (digital ground) pins of the IC are connected to the +5V and ground pins of the USB respectively. The circuit +5V DC and +3.3V DC for operation and voltages derived from the USB port using LDO (low drop out) voltage regulators (not shown in circuit).