App note: 1 kV SenseFET integrated power switch

an_on_AN4176

App note from ON Semiconductors on their FSL4110LR power switch for SMPS power supplies. Link here (PDF)

Some industrial equipment that are supplied from a threephase AC power source such as industrial drives and energy meters often need an auxiliary power supply stage that can provide a regulated low-power DC source for analog and digital circuitry.

This power supply stage requests special specifications such as;
– Wide AC input voltage: 45 VAC to 460 VAC
– Robust system against high line surge
– Protection against magnetic contact test
– Large output capacitance to keep long hold-up timeafter power-off

App note: Power supply topologies – Forward of Flyback? Which is Better? Both!

an_coilcraft_DOC1500

App note from Coilcraft camparing two recognized power supply topologies. Link here (PDF)

Beatles or Stones? Michael or LeBron? Deep dish or thin crust? Forward or flyback? These are just a few of the age-old questions that have been hotly debated over the years, people arguing their opinions with great vigor. But, the truth is, most of the time the answer is both, due to the merits of each.

In this article, we will focus on forward or flyback. We’ll discuss the characteristics of active clamp forward and continuous conduction flyback isolated power supply topologies and demonstrate the design and performance trade-offs of each using two telecom-oriented power supplies as examples.

App note: How to eliminate over stress of MOSFET during start-up of flyback converter

an_richtek_an010

App note from Richtek about their embedded soft-start function to eliminate MOSFET stress. Link here

Switching Power Supply, compared to Linear Power Supply, is widely used due to its advantages, such as small size, light weight, high efficiency, etc. Flyback Converter, one of the switching power supply topologies, is most suitable for power supply systems that are below 150W because of its unique features of isolation between primary and secondary sides, simple circuit architecture, few components, low cost, etc.

Since switching power MOSFETs play a very important role in switching power supply converters, how to effectively eliminate over-stress of MOSFET during the start-up of flyback converters will be the main focus to be discussed in this application note. The three major aspects to be investigated are flyback controller design, feedback stability, and Snubber design.

App note: The four benefits brought by using NCP12600

an_on_AND9682-D

App note discussing extended features of NCP12600, NCP12600 is a multi-mode controller for offline power supplies by ON Semiconductor. Link here (PDF)

Beside the novel multi−mode structure it embarks, the NCP12600 packs a lot of features such as an efficient short−circuit protection architecture, a start−up sequence with a slow switching frequency ramp−up, a fast reset when latched and an auto−recovery scheme when line cycle dropout occurs in latched versions. Let’s discover these novelties in the present application note.

App note: TEA1938T GreenChip SMPS control IC

an_nxp_an11923

TEA1938T SMPS control IC application note from NXP Semiconductors. Link here (PDF)

The TEA1938T is a high-featured low-cost DCM and QR mode flyback converter controller. It provides high efficiency at all power levels and very low no-load power consumption at nominal output voltage in burst mode operation.

To minimize ripple, the burst mode uses a small hysteresis scheme. The TEA1938T is designed to support multiple-output-voltage applications like USB PD (Type C) power supplies. Typical applications include notebooks and tablet adapters, fast charging, and direct charging adapters.

App note: Audible noise reduction techniques for FPS (Fairchild Power Switch) Applications

an_on_AN-4148

Reducing audible noise in switch mode power supplies app note from ON Semiconductors. Link here (PDF)

In general, switched mode power supplies do not generate audible noise when they operate at constant ultrasonic frequencies (>20kHz). However, some switched mode power supplies can produce audible noise at certain load conditions. Most Fairchild Power Switches are designed to enter into burst switching operation at light load conditions to reduce standby consumption, which can cause audible noise when the fundamental frequency of the burst switching bundles is in the range of human hearing.

This application note explains the major sources of audible noise and offers useful tips to engineers to solve the audible noise problem in their Fairchild Power Switch (FPS) applications.

Analysis, operation, and modification of a switchmode power supply (SMPS) for variable output voltage

after_mod

Lindsay Wilson did a teardown/modification of a Chinese SMPS to allow an adjustable output voltage:

I’m currently working on a product which uses a size 2430 “hobby” brushless motor and 25A electronic speed controller (ESC). In its “intended” use, the controller runs from two lithium-ion batteries with a total voltage of around 7.4V, but I want to run it from a mains-derived power supply instead. However, there are no off-the-shelf supplies available with that output voltage.
Fortunately, there is no shortage of inexpensive Chinese switchmode supplies with standard outputs of 5,12,24V etc. Most (all?) of these have the ability to adjust the output voltage slightly, by around ±10%. I reckoned that it should be possible to modify such a supply to provide a fully-adjustable output voltage which could be set to the desired 7.4V. This is by no means a novel idea – many people have modified supplies (a common mod is to increase the output to 13.8V, for ham radio use) – but I haven’t seen a good operational analysis of these supplies, so it’s a good excuse to do some detective work and figure out what makes them tick.

Full details at Imajeenyus homepage.

Check out the video after the break.