The output terminal drive capabilities are low by design in order to control noise.

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The THDN is less than 0.002.

The PCM2702 distortion characteristics are shown in Figure 18.

This is very close to the theoretical minimum of 0.0015 for a 16-bit, 48 kHz, stereo signal, and must be the top level for a USB DAC that tracks at 1 kHz.

As seen from the figure, the PCM2702 requires only a 12 MHz crystal and a few capacitors and resistors as external circuitry.

In order to achieve a low-distortion, high SNR design, please take extra care in laying out the analog power and ground, and the crystal oscillator circuit.

By using a separate regulator from that used in the 3.3 digital power supply, the interference can be minimized.

As for the area around the crystal oscillator, it is best to use short fat traces here too.

It is well known that interference tuning of C1 and C2 in Figure 20 will be required, depending upon the crystal oscillator.

It is easy to design a high gain, but if it goes to far, 3rd, 5th, and higher harmonics are created, and this can be a cause of unusual oscillations.

Damping resistors R2 and R3 (22ohm) are needed to prevent ringing between the device and the USB connector.

Also, on D a pull-up resistor, R1 (1.5 kohm) is needed; according to the USB specification, it must be pulled up to 3.3V.

This is not VBUS (the power line available at the USB connector), so please exercise caution.

Figure 21 shows the interface protocol.

Figure 21a. Connecting to USB after power up.

At this time the analog output does a level shift to bipolar zero and the ZERO terminal changes from 0 to 1.

At this time the PLYBCK terminal goes low, and the SSPND terminal goes high (they are both low asserted).

Then the PC (host) detects that the D terminal has the 1.5 kW pull-up resistor connected, and begins sending start of frame (SOF) packets at 1 ms intervals.

Of course the PCM2702 will work fine whether or not the reset is sent.

After this, the PC issues the PCM2702 a control packet and recognizes PCM2702 as an audio device.

Here the OS comes to know that the connected chip is a Burr-Brown PCM2702.

Burr Brown Japan Pcm2702 Drivers In Windows

The PCM2702 is designed to work with the standard, built-in drivers in Windows 98, Windows 2000, and Mac OS.

The user need only follow the instructions from the OS and click OK.

By double clicking the Multi-Media option under Control Panel and selecting USB Audio, the sound that had been coming from a Sound Blaster card or elsewhere, will now come through the PCM2702.

When an audio data packet arrives, the PCM2702 awaits the next SOF packet and then begins playing back the audio.

Burr Brown Japan Pcm2702 Driver For Mac