WM8903LGEFK/RV Wolfson Microelectronics, WM8903LGEFK/RV Datasheet - Page 175

• Manufacturer Part Number: WM8903LGEFK/RV
• Description: Audio CODECs ULTRA LOW PWR HI FI CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8903LGEFK/RV

• Audio Codec Type: Stereo Codec
• No. Of Adcs: 2
• No. Of Dacs: 2
• No. Of Input Channels: 6
• No. Of Output Channels: 8
• Adc / Dac Resolution: 24bit
• Sampling Rate: 96kHz
• Operating Temperature Range: -40°C To +85°C
• Rohs Compliant: Yes
• Adcs / Dacs Signal To Noise Ratio: 96dB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Production Data
Table 86 Mic Insert and Hook Switch Detect: Example Sequence
w
STEP
10
1
2
3
4
5
6
7
8
9
Mic not inserted. To detect mic insertion, Host processor must initialise interrupts and clear MICDET_INV = 0. At every
step, the host processor should poll the interrupt status register.
Mechanical bounce of jack socket during Mic insertion. Host processor may already detect a mic insertion interrupt
(MICDET_EINT) during this step. Once detected, the host processor can set MICDET_INV = 1, unless mechanical
bounce can last longer than the shortest possible T
1 until step 3.
Mic fully inserted. If not already set, the host processor must now set MICDET_INV = 1. To detect Hook switch press,
the host processor must clear MICSHRT_INV = 0. At this step, the diagram shows no AC current swing, due to a very
low ambient noise level.
Mic fully inserted. Diagram shows AC current swing due to high levels of background noise (such as wind).
Mechanical bounce during hook switch press. The hook switch interrupt is unlikely to be set during this step, because 10
successive samples of the MICBIAS current exceeding the hook switch threshold have not yet been sampled.
Hook switch is fully pressed down. After T
switch threshold have been detected, hence a hook switch interrupt (MICSHRT_EINT) will be generated, and the host
processor can immediately set MICSHRT_INV = 1.
Mechanical bounce during hook switch release. The hook switch interrupt is unlikely to be set during this step, because
10 successive samples of the MICBIAS current lower than the hook switch threshold have not yet been sampled.
Hook switch fully released. After T
threshold have been detected, hence a hook switch interrupt (MICSHRT_EINT) will be generated, and the host
processor can immediately clear MICSHRT_INV = 0.
Mechanical bounce of jack socket during Mic removal. Host processor may already detect a mic removal interrupt
(MICDET_EINT) during this step. Once detected, the host processor can clear MICDET_INV = 0, unless mechanical
bounce can last longer than the shortest possible T
= 0 until step 10.
Mic fully removed. If not already cleared, the host processor must now clear MICDET_INV = 0.
Alternatively, utilising a GPIO pin to monitor the MICBIAS current detect functionality permits the
host processor to monitor the steady state of microphone detection or hook switch press functions.
Because the GPIO shows the steady state condition, software de-bounce may be easier to
implement in the host processor, dependant on the processor performance characteristics, hence
use of the GPIO is likely to simplify the rejection of mechanical bounce. Changes of state in the
GPIO pin are also subject to the time delays t
Further details can be found in the applications note WAN_0213 “WM8903 ECM mic detection using
MICBIAS current”.
SHORT
, 10 successive samples of the MICBIAS current lower than the hook switch
SHORT
, 10 successive samples of the MICBIAS current exceeding the hook
DET
DET
, in which case the host processor should not set MICDET_INV =
, in which case the host processor should not clear MICDET_INV
DETAILS
DET
and t
SHORT
.
PD, Rev 4.0, September 2010
WM8903
175