WM8595 datasheet(10/82 Pages) WOLFSON

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WM8595

Production Data

PD, Rev 4.2, January 2011

TERMINOLOGY

Signal-to-noise ratio (dBFS) – SNR is the difference in level between a reference full scale output signal and the

device output with no signal applied. This ratio is also called idle channel noise. (No Auto-zero or Automute function is

employed in achieving these results).

Dynamic range (dBFS) – DNR is a measure of the difference in level between the highest and lowest components of a

signal. Normally a THD measurement at -60dBFS. The measured signal is then corrected by adding 60dB to the

result, e.g. THD @ -60dBFS = -30dB, DNR = 90dB.

Total Harmonic Distortion (dBFS) – THD is the difference in level between a reference full scale output signal and the

first seven odd harmonics of the output signal. To calculate the ratio, the fundamental frequency of the output signal is

notched out and an RMS value of the next seven odd harmonics is calculated.

Channel Separation (dB) – Also known as Cross-Talk. This is a measure of the amount one channel is isolated from

the other. Normally measured by sending a full scale signal down one channel and measuring the other.

All performance measurements carried out with 20kHz low pass filter, and where noted an A-weighted filter. Failure to

use such a filter will result in higher THD and lower SNR and Dynamic Range readings than are found in the Electrical

Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic

specification values.

Notes:

All minimum and maximum values are subject to change.

This resistance is selectable using VMID_SEL[1:0] – see Figure 47 for full details.

See p81 for details of extended input impedance configuration.

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