Cirrus Logic CS42L73 - Manual (Page 69)

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CS42L73
4.13 Using MIC2_SDET as Headphone Plug Detect
Although the CS42L73 does not have a dedicated headphone plug detect pin, the MIC2_SDET pin may be
used to perform a similar function. However, doing so requires that MIC2_SDET not be used as a micro-
phone button short detect.
To use the MIC2_SDET pin as a headphone detect pin, connect the headphone jack pins to the CS42L73
as shown in
Figure 33 .
.
Next, set register 0x5E bit 6 = 1. If no state change other than MIC2_SDET is required to trigger the INT pin,
then the value of register 0x5E may be set to 0x40. This unmasks the MIC2_SDET status bit (register 0x60
bit 6) so that the INT pin will be driven low or pulled high based on the MIC2_SDET status bit.
With the system connected and registers configured as described above, the CS42L73 will drive the INT pin
low when a high-to-low transition on MIC2_SDET is detected (indicating headphone plug insertion). The INT
pin will also be asserted when a low-to-high transition on MIC2_SDET is detected (indicating headphone
plug removal). The INT pin will remain low unless register 0x60 is read; reading register 0x60 sets the INT
pin high. The MIC2_SDET state (shorted or not shorted) can be read via register 0x60 bit 6 at any time.
Figure 34 summarizes the behavior of the INT pin when register 0x5E = 0x40.
Jack Detect Pin
Tip
Ring
Sleeve
47 k 
100  33 nF
100  33 nF
HPOUT_REF
HPOUTB
HPOUTA
MIC2_SDET
INT
VL Supply
2 k 
To System
Microcontroller
VL Supply
Figure 33. Connection Diagram for Using MIC2_SDET as Headphone Detect
INT = Low INT = High
Read Register 0x60
MIC2_SDET low-to-high transition
MIC2_SDET high-to-low transition Set Register 0x5E = 0x40
(M_MIC2_SDET = 1)
Figure 34. Flow Diagram Showing the INT Pin State in Response to MIC2_SDET State Changes