Strange things can happen at high frequencies. It begins with stray current in your printed circuit board (PCB). What is stray current? Stray current starts with stray voltage, relating through Ohm’s Law (V=IR). Stray voltage refers to a situation where between two points, there exists a voltage potential that should not be there (and wouldn’t […]
FAQ
What is inrush current?
Inrush (in-rush) current is a sudden large flow of current that exceeds the usual, steady-state operating current, and can be a problem for any circuit. Inrush is most often associated with turning on equipment. Inrush current can be caused by large-capacity decoupling capacitors that draw a lot of current as they initially get charged up. […]
The formidable forgotten FETs
The world is full of MOSFETs — they are the cornerstone of most ICs. However, the humble JFET still exists, although it is a bit of a niche market now and not always easy to find. Vishay, who took over the Siliconix brand many years ago, seem to have dropped JFETs now, although Siliconix was one […]
Synchronous buck regulators and overcurrent protection (OCP)
by Haifeng Fan, Intersil, a subsidiary of Renesas Electronics Synchronous buck regulators are widely used in industrial and infrastructure applications to step down 12V rails to point-of-load inputs as low as 0.6V for microcontrollers, FPGAs, memory and peripheral I/Os. Overcurrent protection (OCP) is essential to protect these switching regulators from damage by excessive current. Cycle-by-cycle current […]
Dimming LEDs
As the use of LEDs for area lighting has grown dramatically, with both the use of LED-based replacement bulbs as well as LED-based fixtures for new construction (called luminaires in the trade), the issue of dimming these LEDs becomes more critical. LEDs require a very different technique for dimming than the conventional legacy incandescent bulb. […]
How to power and configure LEDs
LEDs – light-emitting diodes – have largely supplanted other sources of light in many applications. They are used in applications ranging from small on/off power indicators, to small and large alphanumeric displays, to screen backlighting, and even for area and street illumination. It’s well known that LEDs are far more efficient than venerable incandescent lighting, […]
What is a charge pump and why is it useful? (Part 2)
(Part 1 looked at the basic function and operation of the charge-pump switched-capacitor voltage doubler. This versatile topology has some additional interesting considerations and permutations.) What about the capacitor? When MOSFET switches are used, the capacitor is sometimes called a “flying capacitor.” This is a designation which is a holdover from early days of electronics, […]
Top power electronics threads on EDAboard.com – March
(editor’s note: Intrigued by these power electronics problems? Have a question or another solution? Then click the “Read more” link and follow the conversation on EDAboard.com or log in to EDAboard and participate in the power electronics forum thread.) Relationship between Q factor and the coupling factor of two wireless coils – I am testing […]
What is a charge pump and why is it useful? (Part 1)
It’s a very common challenge in circuits to need to convert an available DC source to a lower or higher voltage. For the high-to-low conversion, one option to use a low dropout regulator (LDO), but how to easily transform a lower voltage into a higher one? For AC voltages, the answer is well-known: use a […]
What’s the difference between current sourcing and sinking?
Current can flow in two different ways with respect to the load. Sensors often provide real-world, analog input for embedded applications. MCUs rely on sensors to be their electronic “senses” and actuators to physically interact with world. Interfacing with external devices requires some planning on the part of the designer to ensure efficient operation. One […]
