Other Parts Discussed in Thread: TPS552892, BQ25798
Tool/software:
I wanted to design a power supply for an automotive board that would give a robust 5v line capable of surviving most events. The TPS552872 seemed like a great choice, especially the integrated FET's and the boost feature capable of working down to 3V, which is perfect for a Li-ion emergency backup battery. Having said that, when reading the datasheet, 2 things caught my eye.
1. The output voltage response to a load transient: From the figures, a load step from 0 to 2A would give a greater than 500mV output swing. For most applications, this type of swing in a 5V rail would kill most components in that rail. The load step response was made for a 12V output. How does the transient swing correlate with lower Output voltages? If the 500mV swing is independent of the output voltage, is there a way to add a second stage filter/snubber circuit to suppress that swing to an acceptable level?
2. Recommended PCB Layout/Stack-up: The schematic suggests a Multi-Layer Design, presumably 6 Layers. Is this Stack-up essential for the correct operation of the regulator? I am planning on making the board in two layers, as cost is a priority in the design.
