Designing the PCB for Tougher INA3221 Power Monitor

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This is my first project in KiCAD, and I am mostly using Altium and CircuitStudio, as I have written in one of my blog posts. So, even though the PCB itself is not complex, learning a new tool was a bit of a challenge. I have achieved what I wanted in my design, except for some PCB art work, since import of bitmaps is not directly supported in KiCAD. I can’t learn everything with a first design. Block diagram Up-to-date schematics I initially planned for the power monitor to be compatible with Feathers only (see the previous post), but then I realized that adding Arduino Nano support was possible. Except for this, I haven’t made any significant changes in the schematics. The design files are available on GitHub, you can also download schematics in PDF directly here. PCB design I wanted to keep the design 2-layer, and with some insignificant shortcuts, I kept it at two layers. I have tried to avoid large currents to pass around INA3221 to prevent ground bouncing, so I added some cutouts in the ground. Cutouts are made so that differential traces from current resistor don’t experience ground plane breaks. I didn’t add any ground …

KiCAD as an alternative to Altium Designer?

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At times when I have to do a circuit or PCB design in my professional work I mostly use Altium Designer. I’m not a full-time hardware designer consultant, and do both hardware and software. So, I can’t justify paying several thousands of dollars per year, unless I would be involved in a year or longer hardware design only project. Also, clients usually provide a license seat for me anyways. However, I needed to have a PCB design software for my products and projects. About 2-3 years ago I started a new hunt for it. I have used Eagle before, and have briefly looked at KiCAD. When compared to Altium it feels like 90s, especially KiCAD. I didn’t want to use these, and certainly was not going to pay for unlimited version of Eagle given how outdated it was. I was browsing for the alternatives, and found out that Altium started to offer CircuitStudio, which is basically much lighter version of Altium Designer, and costs couple of hundreds of dollars. They also started to offer CircuitMaker, which is a free cloud based version. These two seemed like the best candidates at the time. CircuitMaker CircuitMaker is targeted towards makers and there …

Designing A Tougher INA3221 Power Monitor

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Following my experiments with setting up a small-scale solar system for charging phones and laptops, I needed a better power meter. I am using a DFRobot I2C Wattmeter (SEN0291) to measure current and voltage of a battery, solar panel and load. It is INA219 based, and has as minimilastic design as other INA219 based boards from Adafruit, Sparkfun or other less known manufacturers. The problem with power meters The problem with all of these boards, is that there is no filtering implemented around the current sense resistor. The pins of INA219 are directly exposed to the voltage on a wire you are trying to measure the current of. If there is any transient voltage higher than 26V between the current sense resistor and ground, the INA219 will be destroyed. In my case, the module would get sometimes destroyed during connection of a load. I have measured the voltage between the current sense resistor and ground during load connection, and maximum voltage reaches 56.7V, which is way above 26V. My conclusion was that it is caused by the high inrush current oscillations. Another disadvantage with all these prototyping modules are the connectors. The screw terminals are low quality, too small and …