We need to reduce the switching noise from the the Vin pin on the TPS82084, because it is interfering with sensitive analog components on one of our designs.
This is for an existing batch of built boards which we would like to continue to use with rework. The noise is conducted to the sensitive components through the ground plane unfortunately, so the better the high frequency decoupling on the Vin pin, the worse the system noise. Our best results come from isolating incoming voltage trace with a ferrite, and adding a series resistor to the input cap at the 82084 to slow down the switching transient. This keeps the high frequency noise to a small bit of copper at the Vin pin. It works great but it leaves a 10ns 8V spikes at Vin, which exceeds the device absolute maximum rating of 7V.
Power source----> [Big decoupler to Gnd] ----> [Low Z Ferrite bead] ----> [Mid sized decoupler with series resistor between cap and ground] --> TPS82084
Questions:
1. By any chance can we leave the spikes there and expect the TPS82084 to function with a reasonable (or at least reduced but predictable) lifetime.
2. Could I rig up a snubber circuit to one side of the exposed inductor on the top of the package, to try to reduce or shift the noise frequency.
3. Any other ideas. Re-layout will happen eventually but we may choose another buck converter unless I can prove this one will behave itself.
