WM8746
Production Data
Test Conditions
AVDD = DVDD = 5V, AGND = 0V = DGND = 0V, TA = +25oC, fs = 48kHz, SCKI = 256fs unless otherwise stated.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Analogue Output Levels
Output level
Load = 10kΩ,
0 dBFS,
1.1
Vrms
(AVDD=5.0V)
Load = 10kΩ,
0 dBFS,
0.73
(AVDD=3.3V)
Gain mismatch
channel-to-channel
1
1
%FSR
kΩ
Minimum resistance load
To midrail or a.c.
coupled
To midrail or a.c.
coupled
1
kΩ
(AVDD = 3.3V)
5V or 3.3V
Maximum capacitance load
Output d.c. level
100
pF
V
(AVDD1-
AGND)/2
Power On Reset (POR)
POR threshold
2.0
V
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. CAP 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.
March 2006, PD Rev 4.0
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
