WM8782_10 Datasheet, PDF (7/20 Pages) Wolfson Microelectronics plc – 24-Bit, 192kHz Stereo ADC

Production Data
WM8782
Test Conditions
DVDD = 3.3V, AVDD = 5.0V, TA = +25^oC, 1kHz signal, A-weighted, fs = 48kHz, MCLK = 256fs, 24-bit audio data, Slave Mode
unless otherwise stated.
PARAMETER
SYMBOL TEST CONDITIONS
MIN
TYP
MAX
UNIT
Digital Logic Levels (TTL Levels)
Input LOW level
VIL
0.8
V
Input HIGH level
V_IH
2.0
V
Input leakage current – digital pad
-1
±0.2
+1
µA
Input leakage current – digital
tristate input (Note 3)
85
µA
Input capacitance
5
pF
Output LOW
Output HIGH
VOL
IOL=1mA
VOH
IOH= -1mA
0.9 x DVDD
0.1 x DVDD
V
V
Analogue Reference Levels
Midrail Reference Voltage
VMID
AVDD to VMID and
–4%
AVDD/2
+4%
V
VMID to VREFN
Potential Divider Resistance
R_VMID
70
kΩ
Buffered Reference Voltage
VREFP
–4%
AVDD/2
+4%
V
VREF source current
IVREF
5
mA
VREF sink current
IVREF
5
mA
Supply Current
Analogue supply current
AVDD = 5V
26
mA
Digital supply current
DVDD = 3.3V
5
mA
Power Down
0.5
mA
Notes:
1. All performance measurements are done with a 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 this is not audible, it may affect
dynamic specification values.
2. VMID is decoupled with 10uF and 0.1uF capacitors close to the device package. Smaller capacitors may reduce
performance.
3. This high leakage current is due to the topology of the instate pads. The pad input is connected to the midpoint of an
internal resistor string to pull input to vmid if undriven.
TERMINOLOGY
1. Signal-to-noise ratio (dB) – Ratio of output level with 1kHz full scale input, to the output level with all zeros into the
digital input, over a 20Hz to 20kHz bandwidth. (No Auto-zero or Automute function is employed in achieving these
results).
2. Dynamic range (dB) – DR 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. 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.
w
PD, April 2010, Rev 4.7
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