Other Parts Discussed in Thread: OPA698
Let’s discuss input and output headroom on the TPA6130A2 DIRECTPATH™ Stereo Headphone Amplifier.
The TPA6130A2 is specified for a Vdd power supply voltage range of 2.5 to 5.5 VDC. Under Absolute Maximum Ratings we see VI Input voltages for RIGHTINx, LEFTINx specified at -2.5 MIN and 3.6 MAX.
For my design Vdd is set to 3.6 VDC. Is RIGHTINx, LEFTINx still -2.5 MIN and 3.6 MAX or is it some X mVs below Vdd?
On the output side does the clipping level vary with Vdd voltage? Datasheet figures 28, 29, and 30 show the Vdd = 5 and 3.6 volt output power curves largely overlaying until lower frequencies and heavier loads. Am I correct this implies the charge pump sets the internal voltage rail for the output stage and holds it constant until heavy loads pull it down?
What I am needing to understand with these questions is what is the maximum AC audio signal voltage on the RIGHTINx, LEFTINx pins the TPA6130A2 can amplify without clipping when it is running off Vdd = 3.6VDC and its gain is set to the max of +4dB? TPA6130A2 is set to stereo headphone drive mode.
In the device being designed upstream of the TPA6130A2 is an OPA698 amp as part of the preamp circuit. Recall that device has a voltage limiting function with input pins VH and VL and the OPA698 will limit its output according to the set voltages on VH and VL. Once I am confident in TPA6130A2’s maximum input levels under the conditions in my circuit VH and VL can be set to avoid overload of TPA6130A2’s inputs or output stages.
