I am using the TPA3118D2 in an application for a musical instrument amplifier. In doing some experimentation for the "next generation" products, I have found a behavior that looks like supply pumping. I am using PBTL configuration from the data sheet, my supply rail has been set to 26 VDC, the load is 4 ohms and the input is single ended 100Hz sine wave.
When I drive the amplifier with a 100Hz sine wave, the TPA3118D2 is shutting down as I drive it near (or before) clipping. I looked at the supply rail and I can see it is being modulated and does indeed increase to a level that would be consistent with reaching the OVLO of the TPA3118D2.
I decided to pull the EVM board off the shelf and ran it under similar conditions but in BTL mode. No problem. So I decided I should run the EVM board in PBTL but the user guide is a bit vague on the load connection. I'm not clear on how the outputs are connected to the load for PBTL.
My questions are as follows;
- Does PBTL mode suffer from supply pumping effects or is there a problem somewhere else causing the behavior?
- What is the proper set-up (load connection etc.) to configure the EVM board in PBTL mode so I can use this as a point of reference?
- How does the PBTL configuration shown in the data sheet application differ from the EVM's configuration?
BTW - My original applications uses the TPA3118D2 in PBTL but with a 24VDC rail and I have not experienced a problem.
Thanks,
Jim
