I'm trying to understand how BTL driver on TI's DRV8662 Piezo Haptic Driver (datasheet) works. What I am confused about is how a 200Vpp output signal can be generated from a driver that only has rails at GND and 100V. If I understand that datasheet correctly the driver looks something like this:
The output according to the datasheet is this:
What I am confused about is that the differential outputs have a common mode voltage of 50V (as shown in figure 8). So how is the voltage difference in between Out+ and Out- signals leads to a 200Vpp swing (as in figure 10) when figure 8 clearly shows that the maximum difference between these two voltages is 100V? How can the output swing to -100V if no negative rail is ever supplied to the part?
I tried reading these documents to clear up my issue but it didn't help.
BTL Speakerdrive Reference Note (link)
Audio Design Note (link)