In this episode of Atmel Edge, Analog Aficionado Paul Rako describes the importance of drawing schematics with inputs on the left and top, as well as outputs on the right and bottom.
“The most fundamental thing about a system-level schematic is that there is a flow to it – and that flow is from left to right and from top to bottom,” Rako explains.
“Anyone can pick it up and they know they can look at the left edge and tend to see inputs, or look at the top and tend to see inputs. Then they can look to the right edge or the bottom and tend to find outputs.”
Well, perhaps it isn’t that simple, says Rako, because what about a bus?
“How do you represent something that has bidirectional flow? Do you put things on the top or the left edge? That’s kind of a style, but if you just stick to these basics, you’ll be a lot better off,” he adds.
Watch as Paul provides a little bit higher level tip than just grounds, capacitors and resistors, plus topics we’re going to discuss in the 101 series. Stay tuned!
In this episode of Atmel Edge, Analog Aficionado Paul Rako discussed three clever tricks to keep your high-speed circuit boards from radiating energy and failing CE or FCC testing.
Flip your planes, stitch around the edges, or bring the power and ground planes really close together to keep them from oscillating and pumping RF out the edges. These three quick PCB layout tricks will help you pass FCC emissions in no time!
More specifically, says Rako, you take inner plane layers on a four-layer board (or more), bringing them to the outside, effectively creating a containment vessel that prevents radiation from escaping. The second?
“Istvan Novak works at [Oracle] Sun Microsystems,” Rako explains. “He says there is prior art; he didn’t invent it, but he figured out you could stitch RCs all around the edge, and that would keep the radiation from not only leaking out, but from bouncing back in.”
As for the third trick, if you go cut up power planes, you can ultimately bring them very close together.
“You can bring them close together and use other planes to contain the RF – distributing your power and ground with intimate one-mil spacing between the planes. That brings the same kind of damping in as the other trick with putting RCs around the edge,” he adds. “So those three tricks are ways to get you through FCC and CE immunity testing.”
In the latest Atmel Edge episode, Analog Aficionado Paul Rako explains how digital buttons, sliders and wheels can be used to make popular sprinkler timers easier to use.
“We’re going to do a system-level redesign, going through this from block diagrams. Then come up with an alternate and then apply some technology that Atmel can help you with. Things like button, wheels and sliders, where you don’t need physical, discrete switches anymore,” said Rako
“I’m going start going through the programming. And that’s where I think, with a redesign and rethinking, and using some modern cool-person things like button sliders and wheels. There’s no physical button. It’s not expensive. You can put a thousand of these buttons on the same circuit board.”
As we’ve previously discussed on Bits & Pieces, Atmel offers market-proven technology for implementing nonmechanical buttons, sliders and wheels on any touch-sensitive device.
These integrated circuits (ICs) enhance the user experience with precision and reliability, while delivering optimized low-power characteristics, a critical requirement for today’s battery-powered handheld and mobile devices. The technology supports simple 1–10 button configurations as well as more complex scanned-matrix configurations of up to 48 buttons – at very low cost per button.
In this episode of Atmel Edge, Analog Aficionado Paul Rako discusses the importance of understanding ground symbols for electronic schematics. As Rako notes, Earth ground, chassis ground, power supply return and shield are all different. This video explains why.
“Earth ground has a very precise meaning and a very precise name, and it’s earth ground. My professor, James T. McLaughlin, at Kettering University previously General Motors Institute, pointed out [that] earth ground is a ten foot copper-clad steel rod,” says Rako.
“And you hammer it into the dirt. And you make sure there’s moisture so it has conductivity. The minute you hook a wire to it, well now you got some inductance. And 12-gauge wire all the way to get to where earth ground has to get, which is this third pin on your wall socket, well now it’s got a little resistance, as well.”
Rako also points out that a car isn’t grounded.
“What you want to use is this symbol, which is chassis common. And chassis common, it’s not just cars, but television, radios, PCs with metal things. Anywhere there’s a metal case or a metal mounting point, that’s chassis common. In America, if a human being can touch that metal, you have to connect earth ground at chassis common,” he notes.
“Underwriter’s Laboratory requires a ring terminal so it doesn’t get pulled off. And that way, if there’s a short of high voltage on to the chassis — a wire or something falls down — then it can seek a ground through this earth ground and trip a circuit breaker instead of electrocuting your customers.”
As Rako emphasizes, semiconductor companies who make chips should be using this symbol, the triangle.
“That is power supply return. You may connect your circuit board in the corners, it may connect to chassis, and maybe you want that,” he adds.
“Maybe you want it to connect at 100 places to get a really good RF connection between the circuit board and the metal chassis. But this symbol would be improper on a circuit board, and certainly earth ground is wrong.”