5 LDO Regulator Considerations other than voltage and current

A lesson in reading the data sheet

Pryamiduino R4 with LDO Regulator Disabled

For an AddOhms series, I created a DIY Arduino I am calling the “Pyramiduino.” It is an ATmega328p based board in the shape of a triangle. Other than being cute, the shape does not offer any other benefit. The design features a 3.3 volt LDO Regulator, which is also the subject of this post.

I forgot a fundamental aspect of design: read the freaking datasheet. The board’s LDO regulator was not turning on. Adding a passive scope probe to the circuit suddenly fixed the problem. The regulator turned on. When touching the enable pin, it measured about 1.25 volts.  While I am sure Rohde & Schwarz would like me to ship scope probe with each board, that was not an option. With the impractical fix in place, I got to thinking about that voltage level. I remembered that the datasheet mentioned about 1.2 volts was needed for the “HIGH” threshold. Which meant, 1.25 volts applied to the pin enabled an active low input. Not only that, I remember the datasheet clearly said it had a pull-down resistor built-in. What was going on?

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DIY Arduino Schematic board and Checklist

Things to consider when designing a custom board, based on an Arduino

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One of the last significant steps in a project is designing the custom PCB. This stage means creating a DIY Arduino board that is custom to the application. Two examples of my past projects are BinBoo, a Binary Clock, and Open Vapors, my reflow oven controller.

While working on a project for a friend, I got to thinking; it would be nice to have a checklist for circuit elements to include on a DIY Arduino board. In the early days, I forgot to add a filter cap to AREF, for example.

These tips are based on an 8-bit AVR design, like the ATmega328p chip. You could apply these tips to other 8-bit AVRs. Until now, I have not designed a custom board around a 32-Bit/ARM board. Though at only $16, I would be tempted to just solder the Teensy module directly to my finished board.

Below is a written list of items for a DIY Arduino checklist. If you’d like to see me design this board in KiCad, check out this AddOhms Tutorial.

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Switching Voltage Regulator Tutorial

AddOhms #18 covers the basics of switching voltage regulators

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A switching voltage regulator is one of my favorite circuits. In school, they were the first circuits I built where I understood how transistors worked. In fact, they were the first circuit I saw an inductor being useful! Switching regulators are incredibly efficient when designed properly. Of course, this detail about design is important. They are not as simple as a linear regulator, which is basically an IC and two caps.

To understand the basics of a switching regulator, I released AddOhms #18 this week. This is video tutorial dedicated the Switching Voltage Regulator. If video tutorials aren’t your thing, then keep reading for my written tutorial.

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Don’t be afraid of learning a new tool

Behind-The-Scenes of AddOhms #14

After moving from learning a new tool to mastery, the resistance for me to switch becomes very high. This can apply to hardware tools like a drill, saw or CNC milling machine. It can also apply to software tools like EAGLE, Programming Languages or video editing software. In AddOhms #14, I gave an overview of the VirtualBench from National Instruments which I’ve covered on this blog as a hands-on, written review and video review.

learn a new tool

Photo courtesy of smuay/Shutterstock.com

For this AddOhms Behind-The-Scenes look, I talk about my experience with changing my tool set, the most critical tool in fact, I use for creating AddOhms Videos. If you’ve ever wondered how I do those hand animations, keep reading for the deepest look yet into my workflow.

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AddOhms Electronics Tutorials DVD Now Available

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When I was in elementary school, I remember Ms. Coker telling us we needed to memorize our multiplication tables because we wouldn’t always have a calculator.  Years later in college I was told, “learn to use the library, it’s not like you can carry the internet in your pocket.”

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Seems strange that I always carry 3 devices on me that do both.

Today a generation of people are growing up with the mass of all human knowledge available to them from birth. No formal education is necessary. And the only need is a modern device with WiFi.

However. Not all accessible information is equal. Which is why I created the AddOhms Electronics Tutorial Video series. Instead of teaching Electrical Engineering as an engineer to other engineers, I’ve created a series that uses simple language to explain electronics to anyone.  And now the growing YouTube series, is available for sale on DVD!

Keep reading to learn more about Volume 1 of the AddOhms DVD.

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(P.S.  The first batch on Tindie were hand made and include a special thank you…)

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5 (Electrical) Engineering Podcasts You Should Subscribe

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Podcasts are an amazing way to extend your knowledge in any subject. This (generally) free content is updated often, comes in a variety of formats, and covers nearly every subject.

Your definition of Podcast might vary from mine. So for this list it means: content regularly produced with the intention of informing on a particular subject which is available either as audio, video, and ideally a RSS feed.

Keep reading to see the different electrical engineering podcasts I listen to.

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AddOhms #7 – Comparing Arduino and Raspberry Pi

The seventh AddOhms TutorialCast has gone “live”. (Gone “uploaded” sounds wrong.) Being able to understand difference between an Arduino and a Pi is a critical point for many new electronics hobbyist. The boards seem so similar, but they are so different.  AddOhms #7: Comparing the Arduino and Raspberry Pi

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AddOhms #6: Analog and Digital

It isn’t always clear what is meant by calling a device or a signal “analog” and “digital”.  This AddOhms tutorial explains the difference between analog and digital by using an analogy to clocks.  Old-school clocks with hands are a great example of “analog” while alarm clocks with digits as their display are an excellent example of “digital”.

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