I'm simulating an LM2596 DC-DC voltage regulator to give me a 5-volt output given a 5 ohm load (1 amp). The circuit is shown below:
In my simulation, after throwing the switch after the LM2596 has reached a stable voltage, the load voltage after the switch spiked to around 6.6 V before stabilizing to around 4.968 volts. I'm trying to mitigate that spike by adding a capacitor and a zener diode before the switch in order to maintain the load voltage at approximately 5 volts. Without D3 and only C5, it spikes to 5.5 V before settling to 4.968 V, and with D3 and C5 together, it gets reduced down to 5.04 V and settles to 4.965 V in a matter of milliseconds. Is this a good method at 'stabilizing' the load voltage when using a regulator and a switch? What are some drawbacks of using a zener diode in this method?
EDIT: The SPICE model I'm using in my simulations is an adjustable regulator which I set to 5 V using a voltage divider, but the IC I plan to use is fixed at a 5 volt output. That's what I'm showcasing in my schematic, a fixed-voltage regulator.
EDIT: I'm basing my circuit off of TI's recommended schematic, a fixed output voltage regulator. The image is below, but I used TI's webbench tool to get the values shown in my schematic above.
EDIT: Below is a simulation of the output DC waveform at the load. Using a 15 V input, I simulated four different variations of the LM2596. The first plot shows the recommended datasheet's parts while the other three show Webbench's part suggestions with and without a post-ripple filter as well as a small 10 nF capacitor on the load at the last plot.