WM8737LGEFL/R Wolfson Microelectronics, WM8737LGEFL/R Datasheet - Page 19

• Manufacturer Part Number: WM8737LGEFL/R
• Description: IC, ADC, 24BIT, 96KHZ, QFN-32
• Manufacturer: Wolfson Microelectronics

Specifications of WM8737LGEFL/R

• Resolution (bits): 24bit
• Sampling Rate: 96kSPS
• Data Interface: 2-Wire, 3-Wire, Serial
• Supply Voltage Range - Analog: 1.8V To 3.6V
• Supply Current: 7.75mA
• Digital Ic Case Style: QFN
• No. Of Pins: 32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Production Data
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ANALOGUE TO DIGITAL CONVERTER (ADC)
Table 8 Zero-Cross Detection Control
The WM8737L uses a multi-bit, oversampled sigma-delta ADC for each channel. The use of multi-bit
feedback and high oversampling rates reduces the effects of jitter and high frequency noise. The
ADC full-scale input level is proportional to AVDD. With a 3.3V supply voltage the full scale level is
1.0 Volt rms (+/-1.414 Volts peak). Any voltage greater than full-scale will overload the ADC and
cause distortion.
ADC THD+N VERSUS POWER CONTROL
The ADCs can be operated in ‘normal mode’, which offers best THD+N performance at the cost of
highest power dissipation, or in ‘low power mode’ which offers significant power savings at the cost of
slightly reduced THD+N performance. The ADCs operating mode is controlled by the LP bit in
register R5. USB mode is not compatible with low power mode, so the LP bit must be set to 0 if USB
mode is selected.
See the ‘Power Consumption’ section for power requirements in both modes.
Table 9 ADC Power Control
ADC DIGITAL FILTER
The ADC filters perform true 24 bit signal processing to convert the raw multi-bit oversampled data
from the ADC to the correct sampling frequency to be output on the digital audio interface. The digital
filter path is illustrated below.
R2 (02h)
Audio Path Left
R3 (03h)
Audio Path
Right
R5 (05h)
ADC Control
REGISTER
REGISTER
ADDRESS
ADDRESS
3
2
1:0
3
2
1:0
BIT
BIT
2
LMZC
LPZC
LZCTO[1:0]
RMZC
RPZC
RZCTO[1:0]
LP
LABEL
LABEL
None (first
gain
change
would
overwrite!)
1
11
None
1
11
0
DEFAULT
DEFAULT
Left Mic preamp Zero-Cross Enable
0: Change gain immediately
1: Change gain on zero crossing only
Left PGA Zero-Cross Enable
0: Change gain immediately
1: Change gain on zero crossing only
Left Zero-Cross Time-Out
00: 256/fs
01: 512/fs
10: 1024/fs
11: 2048/fs (42.67ms at 48kHz)
This timeout applies to both the PGA
and mic preamp zero-cross watchdog
timers.
Right Mic preamp Zero-Cross Enable
Same as LMZC but for right channel
Right PGA Zero-Cross Enable
Same as LMZC but for right channel
Right Zero-Cross Time-Out
Same as LMZC but for right channel
ADC power mode control
0: Both ADCs in normal mode (best
THD+N)
1: Both ADCs in low power mode
DESCRIPTION
DESCRIPTION
PD, Rev 4.1, April 2009
WM8737L
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