Hello,
We are using the DRV8842 bridge driver for switching a large inductor in a magnetics clamping application (inductor around a permanent magnet). With 2 control signals we can set the inductor current in 2 directions so we can choose between extra clamping (magnetic force higher then permanent magnetic force) or no clamping (reverse current). We use currents up to 4.5A at +24V. However when reversing the current a very large voltage spike up to +70V occurred on our first proto type which of course damaged the driver and other components connected with the +24V. After this I have reduced the spike until +30V by placing a large bulk cap of 2200uF.
The problem however is that we have a limited amount of board space and when I want to redesign the board we are looking for a solution requiring less board space. At this moment I have no components at the bottom side of the PCB so it is possible to place some parts at the bottom with a limited height. We are thinking of clamping with a zener and MOSFET that will conduct when the voltage rises above a certain level.
Or are there any other methods to reduce the large voltage spike during switching which requires less board space compared with a 2200uF cap?
Best regards Chris