The Tech Blog

MTBF stands for Mean Time Between Failures. MTBF is a statistical measure of the average time between failures for a repairable system during normal operation. Essentially, it helps predict the period when a system will function without failure. It’s critical for reliability engineering.
MTBF is calculated by taking the total operational time of all units and dividing it by the number of failures observed. It becomes valid only if you have a large sample size of parts tested. You can’t just run a single part for X hrs and claim the MTBF to be the time, when that part fails. Larger the sample size, better the result. MTBF provides an estimate of the reliability and performance of electronic components. This information is crucial for industries where reliability is critical, such as aerospace, automotive, and medical devices. It also helps engineers identify weak points in their designs, allowing them to make necessary improvements to enhance reliability because overall reliability still depends on its weakest link.

There are other related reliability terms similar to MTBF like

FIT (Failures in Time): Indicates the number of failures per billion hours of operation.
DPPM (Defective Parts Per Million): Number of defective parts in a million shipped parts.
MTTF (Mean Time To Fail): Average time to failure for non-repairable systems.

Personally in electronics, I have used MTBF values only for LEDs and relay parts to see how long I can reliably drive them. For these parts, values come with the datasheet. Never really used them for ICs. Seems like high-end PCB CAD software like Cadence has built-in modules for these.
I do see its merits in system design as a whole though. Can anyone senior from the industry comment if you use MTBF values while designing and do you follow that safety protocol like designing? Would appreciate some industry insights on this.

Well, simply put, electronic loads are the reverse of power supplies. They are test instruments that simulate loads on a power source by drawing a controlled amount of current or power. In their simplest form, they function like a large resistor, electronically controlled to pass a specific amount of power. However, there’s much more to them than just that.

They are used in many applications. Personally, I use them for battery testing to measure capacity, determine discharge rates, and perform lifecycle testing with controlled loads. This helps ascertain how many charge cycles a battery can endure. They are also used for lifecycle testing of power supplies and stress testing to check if they can handle specific power outputs.

A quality electronic load tester offers various modes. The Constant Voltage (CV) mode fixes the voltage regardless of the current, useful for simulating LED loads by adjusting the resistance internally to maintain the voltage. Similarly, there are modes like Constant Current (CC), Constant Power (CP), and Constant Resistance (CR) where one parameter is fixed while the others vary. CP mode is ideal for battery load capacity simulation, while CR mode is handy when you need the load to act as a resistor with varying voltage and current. The CC mode is suitable for basic current sinking applications to test if the input supply voltage drops at constant currents.

So, what are things you need to look at before you purchase an electronic load? For hobby and non-precision applications, you can build one or get relatively cheap ones online. The one shown in the picture is a 150W load capable of operating in all the modes mentioned earlier. If you need something more advanced, there are benchtop models that are slightly more expensive. Start by determining the capacity rating required for your application, then you can narrow down your options based on size, the number of independent channels, and price. Remember these considerations and modes before you decide to buy one.