WM8351CGEB/RV WOLFSON [Wolfson Microelectronics plc], WM8351CGEB/RV Datasheet - Page 99

• Manufacturer Part Number: WM8351CGEB/RV
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

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The WM8351 can detect when a microphone has been plugged in, and/or when the microphone is
short-circuited. It detects these events by comparing the current drawn from the MICBIAS pin against
two thresholds. The thresholds for plug-in detection and short-circuit detection are programmable.
A MICBIAS current above the MCDTHR threshold level is used to indicate that a microphone is
plugged in, and is associated with the CODEC_MICD_EINT interrupt. If the bias current exceeds the
MCDSCTHR limit, this indicates a microphone short-circuit condition, and the WM8351 raises a
CODEC_MICSCD_EINT interrupt. See Section 13.12.7 for further details. Note that the MICBIAS
current thresholds are subject to a wide tolerance - up to +/-50% of the specified value.
Microphone detection requires the internal slow clock to be enabled - see Section 12.3.6.
R8 (08h)
Power Mgmt 1
R74 (4Ah)
Mic Bias
Control
Note: MIC_DET_ENA can be accessed through R8 or through R74. Reading from or writing to either
register location has the same effect.
Table 49 Controlling Microphone Bias Current Detection
13.12.2 MICROPHONE DETECTION
ADDRESS
BIT
4:2
1:0
8
7
MIC_DET_ENA
MIC_DET_ENA
MCDTHR [2:0]
MCDSCTHR
[1:0]
LABEL
DEFAULT
000
00
0
0
Enable MIC detect:
0 = disabled
1 = enabled
Threshold for bias current detection
000 = 160µA
001 = 330µA
010 = 500µA
011 = 680µA
100 = 850µA
101 = 1000µA
110 = 1200µA
111 = 1400µA
These threshold currents scale
proportionally with AVDD. The values
given are for AVDD=3.3V.
Threshold for microphone short-circuit
detection
00 = 400µA
01 = 900µA
10 = 1350µA
11 = 1800µA
These threshold currents scale
proportionally with AVDD. The values
given are for AVDD=3.3V.
DESCRIPTION
PD, April 2012, Rev 4.5
WM8351
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