Hello TI forum members,
I am creating an audio I/O device with the TLV320AIC3105 and I am required to determine the in and output impedance. So far I measured the in and output impedance according to the methods described on this site: www.sengpielaudio.com/calculator-InputOutputImpedance.htm
The line-in impedance measured is 30kOhm for both channels, which fits perfectly in the 20kOhm to 80kOhm requirement from the datasheet. The output impedance measured is 32 ohm for the left channel and 50 ohms for the right channel. However, there is nothing stated in the datasheets about the line-out impedance.
So, my questions are as follows:
1) Why do my measured line-output impedances differ? I don't use any filtering and measure on a line directly from the CODEC to the output jack, so no hardware between codec and output that could cause a difference.
2) What is the nominal codec line-out impedance? Are 32 and 50 ohms normal?
3) Can somebody explain what exactly is meant by the recommended operation of max 10kOhm line-out load? The 2007/2008 datasheets state a recommended line-out load of minimal 10kOhm and a minimal of 16 ohms for the headphone output. The 2014 revision states a maximum of 10kOhm line-out and 16-ohm headphone out. How should this be interpreted? The 2007/2008 revisions seem to state that my earplugs are not recommended, however they seem to work fine on line-out. And the 2014 revision seems to state that a headphone with a larger impedance than 16ohms should not be connected, however apple earplugs already have a 40-ohm impedance.
Thanks in advance!
Kind regards,
Remy
