Back to Basics: What does p in 1080p stand for?

Yesterday I was doing some research into display drivers for a project and got to learn about how the TV displays evolved. One of the things I learned was contrary to popular belief, it’s not pixels – it stands for “progressive.” Let me explain.

The “1080” part of 1080p stands for the number of pixels in the vertical direction of your display. It can be 720, 1440, 2160, etc. When you are trying to display something on a screen(called “scanning” the screen), there are 2 ways of doing it. Interlaced scan and Progressive scan. In an interlaced scan, the image to be displayed is divided into two fields, and only half of the lines are shown at a time. The first field includes the odd-numbered lines(1,3,5,..,1079), and the second field includes the even-numbered lines(2,4,6,…,1080). These fields are then displayed alternately to create a complete frame. Meaning, that at a single time, only half the screen is refreshed to a newer image. This was done in the olden days of CRT Displays to show higher-quality images on screen with only half the bandwidth. It reduced the transmission rate needed for videos. But this has drawbacks for fast-moving scenes, you may observe some stripes/artifacts in the screens for these videos.

Now Progressive scans, on the other hand, displays or “scans” every 1080 lines one by one, top to bottom, and refreshes every pixel on the screen at the same time. That means full bandwidth is needed to show a frame. Progressive scan provides a smoother, faster, and more detailed image, making it a preferred choice for modern displays. You don’t find interlaced formats that much these days.

Now you know what “p” means. Who knew pixels could be so progressive? ????

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Back to Basics: Battery Strap Fuses

Battery strap PTCs, or Positive Temperature Coefficient devices(a fancy way of saying its resistance increases with an increase in temperature), are components designed to protect batteries and associated circuits from overcurrent conditions. These are relatively unknown to folks outside the battery industry. Please don’t mistake them for the SMD fuses we fuse while designing PCBs for protection. Although they work on similar principles, the strap-ones are uniquely thin-shaped and attached directly to the batteries.

Battery strap PTCs act as self-resetting fuses. When an overcurrent condition occurs, the PTC heats up and its resistance rises dramatically, reducing the current flowing through it. This effectively limits the current to a safe level. Once the fault or overcurrent condition is removed, the PTC cools down, and its resistance decreases, allowing normal current flow to resume. Like all fuses, it will have a specific hold current(current allowed to pass in normal operation) and a trip current(current at which the device goes into high resistance mode). One major thing to keep in mind is that these hold/trip currents are temp-specific; as temperature increases, these values fall, and they will trip faster. In a way, it’s a nice thing because when the battery shorts, the temp shoots up and it reaches the trip point faster, but make sure it doesn’t trip in normal ambient or when the battery is getting charged(as the temp increases)

These fuses are usually spot welded or crimped on the battery terminals directly. It forms a great first line of protection in large battery packs and plays a crucial role in reliable and long-lasting battery solutions.

Have you ever used them in a project? How was your experience with it?

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