Pre-Production
WM8904
OTHER PARAMETERS
VMID Reference
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Midrail Reference Voltage
(VMIDC pin)
-3%
AVDD/2
+3%
V
Charge up time (from fully discharged
to 10% below VMID)
External capacitor
890
μs
4.7F
Microphone Bias (for analogue electret condenser microphones)
Additional test conditions: MICBIAS_ENA=1, all parameters measured at the MICBIAS pin
PARAMETER
Bias Voltage.
SYMBOL
TEST CONDITIONS
MICVDD = 2.5V
MIN
TYP
MAX
UNIT
VMICBIAS
-10%
3/2 x AVDD
+10%
V
Note: 7/6 and 9/10 are available
only if MICVDD > AVDD.
Note: 3/2 and 4/3 are available
3mA load current,
MICBIAS_SEL = 1xx
MICBIAS_SEL = 011
MICBIAS_SEL = 010
MICBIAS_SEL = 001
MICBIAS_SEL = 000
-10%
-10%
-10%
-10%
4/3 x AVDD
7/6 x AVDD
10/9 x AVDD
9/10 ×AVDD
200
+10%
+10%
+10%
+10%
only if MICVDD ≥ 2.5V.
Drop out voltage between
MICVDD and MICBIAS
mV
Maximum source current
Noise spectral density
IMICBIAS
PSRR
4
mA
At 1kHz
19
67
nV/√Hz
Power Supply Rejection Ratio
MICVDD to MICBIAS
1kHz, 100mV pk-pk
MICVDD = 1.71 V
20kHz, 100mV pk-pk
MICVDD = 1.71 V
1kHz, 100mV pk-pk
MICVDD = 2.5 V
76
88
84
61
70
54
79
dB
20kHz, 100mV pk-pk
MICVDD = 2.5 V
1kHz, 100mV pk-pk
MICVDD = 3.6 V
20kHz, 100mV pk-pk
MICVDD = 3.6 V
Power Supply Rejection Ratio
PSRR
1kHz, 100mV pk-pk
AVDD = MICVDD = 1.8 V
20kHz, 100mV pk-pk
AVDD = MICVDD = 1.8 V
dB
MICVDD and AVDD to
MICBIAS
MICBIAS Current Detect Function (See Note 1)
Current Detect Threshold
MICDET_THR = 00
80
A
(Microphone insertion)
Current Detect Threshold
60
(Microphone removal)
Delay Time for Current Detect
Interrupt
tDET
3.2
ms
MICBIAS Short Circuit (Hook Switch) Detect Function (See Note 1)
Short Circuit Detect Threshold
(Button press)
MICSHORT_THR = 00
600
A
Short Circuit Detect Threshold
(Button release)
400
Minimum Delay Time for
tSHORT
47
ms
Short Circuit Detect Interrupt
Note 1 : If AVDD 1.8, current threshold values should be multiplied by (AVDD/1.8)
PP, Rev 3.3, September 2012
19
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
