WM8738 Production Data
w
PD, Rev 4.5, February 2012
6
ELECTRICAL CHARACTERISTICS
Test Conditions
AVDD = 5.0V, AGND = 0V, DVDD = 3.3V, DGND = 0V, T
A
= +25
o
C, fs = 48kHz, MCLK = 256fs unless otherwise stated.
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
Digital Logic Levels (TTL Levels)
Input LOW level V
IL
0.8 V
Input HIGH level V
IH
2.0 V
Output LOW V
OL
I
OL
= 1mA 0.1 x DVDD V
Output HIGH V
OH
I
OH
= 1mA 0.9 x DVDD V
Pull down resistance (FMT,
NOHP)
R
PD
100 k
Analogue Reference Levels
Reference voltage V
CAP
AVDD/2 –
50mV
AVDD/2 AVDD/2 +
50mV
V
Buffered reference voltage V
REF
V
CAP
V
Potential divider output
impedance
R
CAP
40 50 60 k
Input to ADC
Input Signal Level (0dB) V
RIN
/
V
LIN
1.0 Vrms
SNR (Note 1)
A-weighted, 0dB gain
@ fs = 48KHz
90 dB
SNR (Note 1)
A-weighted, 0dB gain
@ fs = 96KHz
90 dB
SNR (Note 1)
A-weighted, 0dB gain
@ fs = 48KHz, AVDD =
3.3V
90 dB
Dynamic Range (Note 2) DNR
A-weighted, -60dB full
scale input
85 97 dB
Total Harmonic Distortion (THD)
(Note 3)
-1dB input, 0dB gain -87 dB
ADC channel separation (Note
5)
1KHz input 95 dB
Power Supply Rejection Ratio
PSRR 1kHz 100mV
p-p
50 dB
20Hz to 20kHz
100mV
p-p
45 dB
Input Resistance
20 k
Input Capacitance
10 pF
Notes
1. Ratio of output level with 1kHz full scale input, to the output level with the input open circuited, measured ‘A’ weighted
over a 20Hz to 20kHz bandwidth using an Audio analyser.
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. VREF and CAP de-coupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).
4. This data is measured, using an active filter on the device inputs.
