CS4207 Datasheet, PDF (30/144 Pages) Cirrus Logic – Low-power, 4-in / 6-out HD Audio CODEC with Headphone Amp

5. PRESENCE DETECTION
CS4207
5.1 Jack Detection Circuit
The jack detection circuit provides attachment for to up to four pluggable jacks as described in the High Def-
inition Audio Specification. Each jack has an isolated switch (normally open), as shown in Figure 7, which
closes when a plug is inserted into that jack. A “power of two” parallel resistor network is connected to The
SENSE_A pin as shown. The codec will measure the impedance of this network to determine which jacks
have plugs inserted and set (or clear) the corresponding “Presence Detect” bit in the “Pin Sense” control for
that Pin Widget. The jack detect circuitry will remove switch bounce of up to 250-ms duration.
To Codec
To Codec
nc
Line Out 1
Left & Right
To Codec
To Codec
nc
Line In
Left & Right
To Codec
To Codec
nc
Mic In
Left & Right
VA
2.67 kΩ
+/- 1%
To Codec
To Codec
nc
5.1 kΩ
+/- 1%
10.0 kΩ
+/- 1%
20.0 kΩ
+/- 1%
39.2 kΩ
+/- 1%
Headphone Out
Left & Right
To Sense_A
Figure 7. Jack Presence Detect Circuit
5.1.1
Presence Detection and Unsolicited Response
The Pin Widget, if enabled to generate an unsolicited response, will deliver one such response for each
“de-bounced” state change of the “Presence Detect” bit. The “Presence Detect” bit will be stable and read-
able at the time an unsolicited response is issued. In sensing the insertion or removal of a jack the codec
will measure the impedance continuously to determine when to report a change of state. Reporting of
state change and change in the presence detect state bits will not occur until any impedance change has
initially stabilized for approximately 250ms. Following this de-bounce period, the codec will report an un-
solicited response, if enabled and the HD Audio BITCLK running, within 10ms. If the HD Audio BITCLK is
not running, then the request to wake the Link will occur within 10ms.
Once an unplug or plug event has been signaled to the host via the unsolicited response, another change
of the presence detection bits will not be generated unless the jack state has been sensed (de-bounced)
continuously for at least 250ms.
Pin Widgets programmed to generate Unsolicited Responses for Presence Detection state changes will
continue to function in all power states. When generating an Unsolicited Response for a plug event when
the link is in a low power state (when RESET is asserted low) sending of an Unsolicited Response will
wait until after the power state change request and initialization request, the codec initialization sequence
are complete and the first verb is received to prevent the response from being lost due to software tran-
sition to active power state.
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DS880F1