MAX9853 Maxim Integrated Products, MAX9853 Datasheet - Page 41

• Manufacturer Part Number: MAX9853
• Description: (MAX9851 / MAX9853) Stereo Audio CODECs
• Manufacturer: Maxim Integrated Products

Microphone detection is provided by the microphone
bias circuitry. Set RBEN, MICLEN, and MICREN to 1
(register 0x12, bit B1 and register 0x1B, bits B1 and
B0) to enable the microphone bias circuitry. The micro-
phone bias voltage is compared with two thresholds,
95% and 10% of V
three output-impedance states: high, medium, and low.
The high-impedance state occurs when there is no load
on the EXTMICBIAS pins. The medium state occurs
when the load is an electret module or an amplified
microphone biased at midsupply. The low state occurs
when the microphone pin is shorted to AGND by a
hook switch or an accessory logic/identification pin.
Table 3. HSDET Bit Decode
Table 4. Example Headset Configurations
*Test 2 is to be performed after Test 1 finds HPR and HPL High. Test 2 is needed only to determine if a balanced mono speaker is
connected to HPR and HPL.
Stereo Audio CODECs with Microphone, DirectDrive
No External Connector
3-Pole Connector
Mono HP, Mono Microphone
4-Pole Connector
Stereo HP, Mono Microphone
Mono HP, Stereo Microphone
5-Pole Connector
Stereo HP, Stereo Microphone
Test 2 Only*
No HP
Mono Balanced HP
Mono Balanced HP, Mono Microphone
Mono Balanced HP, Stereo Microphone
[XX1XXX]
[XX0XXX]
[XXX1XX]
[XXX0XX]
[11XXXX]
[01XXXX]
[00XXXX]
[XXXX11]
[XXXX01]
[XXXX00]
Headphones, Speaker Amplifiers, or Line Outputs
HSDET
HEADSET CONFIGURATION
______________________________________________________________________________________
INTMICBIAS
HPR
High
Low
x
x
x
x
x
x
x
x
. The thresholds define
HPR
High
Low
Low
Low
Low
Low
Low
Low
Low
High
HPL
Low
x
x
x
x
x
x
x
x
HPL
High
High
High
High
Low
Low
Low
Low
Low
Alternatively, hook switches that disconnect the micro-
phone can be detected by looking for the high state.
Headphone detection is accomplished by placing a
small pullup current on HPL and HPR. For proper head-
phone detection, make sure that the headphone ampli-
fiers are disabled. Set HSTEST to 01 (register 0x19, bit
B1 and B0) to enable headphone Test 1 (see Table 5).
The sense bias for the headphone pins attempts to pull
both HPL and HPR up to AV
avoid creating an audible disturbance on the head-
phones. When a stereo headphone is connected, both
HPR and HPL are pulled low. When no headphone is
connected, or a balanced mono speaker has been
EXTMICBIASL
EXTMICBIASL
High
Mid
Mid
Mid
Mid
Mid
Mid
High
Low
Mid
X
X
x
x
x
x
x
x
x
DD
with a low current to
EXTMICBIASR
EXTMICBIASR
High
High
High
High
High
Low
Mid
Mid
Mid
Mid
X
X
x
x
x
x
x
x
x
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