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I am using the TI chip TPS65930 along with a small 33OHM speaker which is also utilized as a mic by simply speaking into it. I have a few questions regarding this IC that I hope some of you can help me out with.
SPEAKER CONFIGURATION:
According the data manual on page 56, I am shown that the gain of the predriver ranges up to 30dB but I am not given any information about the input peak-to-peak voltage and its max and min values. The predriver is able to output 1.5Vpp which should be plenty for my speaker so I am trying to see if I can avoid using an active amplifier and just use some filtering instead. The biggest question I have right now is why do you need a load impedance of at least 10kOHM/50pF for the predriver? My speaker is only 33OHMs which is significantly less. If you take a look at Figure 6-2 in the data manual, it shows the predriver output from the chip going into a 10kOHM/50pF load network and then the TPA2010D1 Class-D amplifier. Is this really necessary? I would rather just come directly out of the predriver from the TPS65930 chip, take that output through a passive filter network and then send the signal straight to the speaker. But how do I do that if my load impedance needs to be so high? Also just to confirm section 6.1.1, it says that there are two terminals named PreD.LEFT and PreD.Right, does that mean there are two separate predrivers?
MIC CONFIGURATION:
Same scenario here, I would like to avoid using any external amplifiers and see if the TPS65930 is able to amplify the signal from the speaker/mic enough, after talking into it. The input signal can be as small as 1-3mVpp so my concern is that such a small input may be to low to get proper amplification. If I am reading the data manual correctly, both the Mic and AUX are part of the Uplink path and have 2 amplification stages, which can add up to 61dB according to table 6-10. I plan on using the mic with differential inputs. To be honest I can't tell much from the data manual on how to design the mic section, any insight would be greatly appreciated.
Thank you for reading.
All the best
SPEAKER CONFIGURATION:
According the data manual on page 56, I am shown that the gain of the predriver ranges up to 30dB but I am not given any information about the input peak-to-peak voltage and its max and min values. The predriver is able to output 1.5Vpp which should be plenty for my speaker so I am trying to see if I can avoid using an active amplifier and just use some filtering instead. The biggest question I have right now is why do you need a load impedance of at least 10kOHM/50pF for the predriver? My speaker is only 33OHMs which is significantly less. If you take a look at Figure 6-2 in the data manual, it shows the predriver output from the chip going into a 10kOHM/50pF load network and then the TPA2010D1 Class-D amplifier. Is this really necessary? I would rather just come directly out of the predriver from the TPS65930 chip, take that output through a passive filter network and then send the signal straight to the speaker. But how do I do that if my load impedance needs to be so high? Also just to confirm section 6.1.1, it says that there are two terminals named PreD.LEFT and PreD.Right, does that mean there are two separate predrivers?
MIC CONFIGURATION:
Same scenario here, I would like to avoid using any external amplifiers and see if the TPS65930 is able to amplify the signal from the speaker/mic enough, after talking into it. The input signal can be as small as 1-3mVpp so my concern is that such a small input may be to low to get proper amplification. If I am reading the data manual correctly, both the Mic and AUX are part of the Uplink path and have 2 amplification stages, which can add up to 61dB according to table 6-10. I plan on using the mic with differential inputs. To be honest I can't tell much from the data manual on how to design the mic section, any insight would be greatly appreciated.
Thank you for reading.
All the best
