When you hear the word “snubber”, what does it bring to mind?
Perhaps it makes you think of the quintessential absent-minded professor and his super-bouncy invention. Or on the other hand, maybe it makes you think of that boy or girl you asked to the 10th grade homecoming dance — the snubber would’ve been a good nickname for that person (maybe I’m just projecting here).
In the word of electronics, snubber is not only a fun word to say, but it is also a practical and essential part that helps keep your electronics design safe and functional.
What is a Snubber?
A snubber is a device that is used to limit (or “snub”) voltage transients in electrical systems. In an electrical system where there is a sudden interruption of current flow, there can be a corresponding significant rise in voltage across the device. This can result in two things — 1) it can cause electromagnetic interference, which can in turn either cause the device itself to act wonky or it can have a negative effect on nearby systems, and 2) if the spike in voltage is more than the system can tolerate, it can cause significant and sometimes catastrophic damage to the device itself. Both of those outcomes are not ideal — but that’s where the snubber comes to the rescue.
There are several different forms of snubbers. We’ll take a brief, topical look at each one and how they function and give you some insight into which option might be right for your design.
Snubber Diode
First, you have the diode snubber. This is used in systems running on DC current, and it utilizes a rectifier diode as the snubber. It basically works like this — the diode is wired in parallel with the load (like an electric motor), but it is set up so that it does not conduct under normal use. When the current is interrupted, the inductor current flows through the diode instead. The stored energy is then slowly released via the diode voltage drop. The disadvantage of this set up is this slow dissipation of energy is just that — slow. As a result, the inductor may continue to be active longer than you want.
RC Snubber
RC snubbers are typically the most popular choice in electronic system design and are applicable for both AC and DC systems. RC stands simply for resistor (R) and capacitor (C), which are connected across a switch. Since the voltage across a capacitor cannot change instantaneously, any voltage spikes will be mitigated (as long as they are sustained — which I suppose wouldn’t be a “spike” in that case).
Finally, another option is a solid-state snubber, which functions similarly to the diode snubber but relies instead on a varistor or two inverse-series Zener diodes. These designs dissipate power more quickly and can protect against over voltage with both polarities.
How to Use a Snubber
If you’re looking for more information on how to incorporate a snubber into your next project, check out our reference designs, which include many forms of snubbers. We also have a massive selection of capacitors, resistors, and diodes to help you build the snubber your design wants (and needs).