WM8734

Advanced Information

w

AI Rev 2.2 November 2001

6

Test Conditions

otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Line Output for DAC Playback Only (Load = 47k ohms. 50pF)

0dBfs Full scale output voltage

At LINE outputs

1.0 x

AVDD/3.3

Vrms

SNR (Note 1,2,3)

A-weighted,

@ fs = 48kHz

90

100

dB

SNR (Note 1,2,3)

A-weighted

@ fs = 96kHz

98

dB

SNR (Note 1,2,3)

A-weighted,

@ fs = 48kHz,

AVDD = 2.7V

93

dB

Dynamic Range (Note 3)

DNR

A-weighted, -60dB full

scale input

85

95

dB

1kHz, 0dBfs

-88

-80

dB

THD

1kHz, -3dBfs

-92

dB

1kHz 100mVpp

50

dB

Power Supply Rejection Ratio

PSSR

20Hz to 20kHz

100mVpp

45

dB

DAC channel separation

100

dB

Notes:

1.

Ratio of output level with 1kHz full scale input, to the output level with the input short circuited, measured ‘A’ weighted

over a 20Hz to 20kHz bandwidth using an Audio analyser.

2.

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.

3.

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.

4.

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 attentuation (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.