Most of you would be familiar with a power line fuse (If not, please refer to my older posts). Fuses are parts put in series at the input stage to protect the circuits downstream. Thermal fuses protect either by sacrificing themselves(one-time fuses) or by self-cutting-off to reduce overcurrent. There is another class of devices called eFuses whose sole job is to provide better protection to your circuits than discrete/thermal fuses.

eFuse is an active IC solution with protection features against overcurrent, overvoltage, undervoltage, reverse polarity input, and inrush current. Think of it as an all-in-one solution for circuit protection. Let’s take an example of short circuit protection. Discrete PTC fuses work by changing their resistance when a trip current is hit, but the reaction time is pretty linear and takes time. Meaning that the chances of the circuit going up in smoke are high. Whereas eFuses are much faster to react in these scenarios cutting off power nearly instantaneously(Less than a 1ms!). You need a lot of components to provide the same protection for all the above to even get remotely close to the functionalities of eFuses ie) it takes up circuit space.

eFuses absolutely shine in cases where there are parts that will get plugged in “hot”(Think server parts, SSDs/HDDs, Motors that get pulled in and out while powered on). There will be a huge inrush current trying to charge the decoupling capacitors of the hotplugged device, which can cause voltage droop in the rest of the circuit. This is solved in eFuses by doing a controlled ramp-up of the voltage and current for the circuits it’s protecting. All in all, eFuses are the one-stop solution if you need all these protections. Yes, they are slightly more expensive but worth it when you are protecting high-value components in your circuit.

Have you used them before? Would love to hear about your experience working with them.

I have some sort of fascination towards cooling tech in electronics.? We have discussed heat pipes and how they work earlier. I was recently exploring a project and came across another bit of tech called Vapour Chambers. These are the unsung heroes that silently keep the high-end phones and laptops from turning into hotplates.

How does it work? Vapour Chambers operates on the principles of phase-change cooling. Filled with a small amount of working fluid, typically water or ethanol, these flat, sealed chambers absorb heat from a heat source. As the temperature rises, the fluid evaporates, creating vapour that spreads within the chamber. The vapour then reaches a cooler region, condenses back into liquid, and the cycle repeats. This continuous phase change effectively transports heat away from the source. Similar to the fundamental operation of a heat pipe.

Where it differs is in size, vapour chambers are made extremely thin and have a 2D planar sheet structure(Not like a pipe). It’s ideal for applications where space is a premium. The construction involves two thin, parallel plates sealed together with a small gap between them or you can take a large diameter copper tube and flatten it along one of the diameters to have a tiny space in between and then seal the edges. Because of its size, it allows for more even and faster heat transfer from one region to another(higher thermal conductivity) as heat spreads in a 2D plane(In a heat pipe it’s linear). Vapour chambers can handle heat up to 450W of heat whereas heat pipes maxes out at around 125W. Vapour chambers are usually pricier than comparable heat pipes.

In a nutshell, Vapour Chambers brings a sleek, efficient solution to the table, ensuring our devices stay cool. Look into them, if you are working on high heat transfer devices in a space-constrained region. But remember both heat pipes and vapour chambers are not heat sinks, their primary job is to spread the heat to make life simpler for an actual heatsink.