q: how to drive headset with microphone with PCM CODEC IC?

[kobik]

pcm codec ic

Hi all,

i am designing a Bluetooth device that need to drive cell phone stereo headset with microphone.

the Bluetooth module has a PCM interface (13 bit linear/A-LAW/U-LAW)
the Audio output is single ended speaker & microphone via 2.5mm audio JACK (mic, left, right , GND)

i found several PCM CODEC from TI & OKI but they all driving deferential speaker and deferential microphone.

how can i drive my single ended headset with TI or OKI components?
also i have stereo headset my requirements allow me to drive only one speaker (mono)

best regards,
kobik

 

[Vamsi Mocherla]

One good thing is to worry about the impedance matching of the headset. I suppose that a headset has a 32/16 ohm load. The speaker amplifier should be able to drive the microphone when the connection is made. Only thing you have to worry about is the bias levels on the headset, because a headset bias amplifier is usually constructed.