WM8721

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WOLFSON MICROELECTRONICS LTD

PP Rev 1.3 November 2000

5

Test Conditions

256fs unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

SNR (Note 1,2)

A-weighted

90

97

dB

0.1

60

0.1

60

%

dB

THD

1.0

40

1.0

40

%

dB

Power Supply Rejection Ratio

PSSR

1kHz 100mVpp

50

dB

20Hz to 20kHz

100mVpp

45

dB

Programmable Gain Maximum

Programmable Gain Minimum

1kHz

6

-73

dB

Programmable Gain Step Size

1kHz

1

dB

Mute attenuation

1kHz, 0dB

80

dB

Notes:

1.

Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured ‘A’

weighted over a 20Hz to 20kHz bandwidth.

2.

All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use

such a filter will result in higher THD+N 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.

3.

VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).

TERMINOLOGY

1.

Signal-to-noise ratio (dB) - SNR is a measure of the difference in level between the full scale output and the output

with no signal applied. (No Auto-zero or Automute function is employed in achieving these results).

2.

Dynamic range (dB) - DNR is a measure of the difference between the highest and lowest portions of a signal.

Normally a THD+N measurement at 60dB below full scale. The measured signal is then corrected by adding the 60dB

to it. (e.g. THD+N @ -60dB= -32dB, DR= 92dB).

3.

THD+N (dB) - THD+N is a ratio, of the rms values, of (Noise + Distortion)/Signal.

4.

Stop band attenuation (dB) - Is the degree to which the frequency spectrum is attenuated (outside audio band).

5.

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.

6.

Pass-Band Ripple - Any variation of the frequency response in the pass-band region.