Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [switch-mode-power-supply]

A switch-mode power supply (SMPS) switches been fully-on and fully-off states quickly to maintain voltage regulation. They offer lower power dissipation and run cooler than linear regulators that continually dissipate power through a transistor.

Switching Power Supply Design
ISBN: 978-0071482721 (3rd Ed.) by Abraham Pressman, Keith Billings, Taylor Morey

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What is the role of the diode D1 in this ramp generator circuit?

The circuit below is a ramp generator used in switched power supplies to generate a saw-tooth signal for compensation, but I don't really understand what is the role of the diode D1 in the circuit ?? simulate this circuit – Schematic created using…
learn design
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What's the goal of diode and resistor in parallel on SMPS?

While reading schematics diagrams from several switch mode power supplies of LCD TVs, I noticed that the pin which delivers the PWM pulse to the gate of a MOSFET has a diode and resistor in parallel. Some diagrams don't have it. But there are lot…
NIN
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What is wrong with this simple SMPS?

I've been reading up on power electronics lately and as a challenge (and also a learning exercise), designed my first switching power supply - a buck converter in this case. It is intended to supply 3.5-4.0V (decided by diode reference source) and…
Mark K Cowan
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SMPS circuit components need some explaination

I am pretty new to SMPS circuits. I understand there's a bleeder resistor, a flyback diode circuit to power the transistorized osc circuit. I guess that the current around the MOSFET will be like a pulse train. Q1: What is the role of R1, D1 & C1?…
seccpur
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LM2596 buck converter overheats converting 36DC -> 5DC at 600mA

In my circuit I'm using an assembled LM2596 converter module (those which are like $2 on ebay). The input voltage is 26V AC (current 140mA), which is rectified (making it ~36 peak DC), and feeds the buck converter. The output is 5V DC, 600mA. All…
George Y.
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What is the "DC OK" relay used for on a power supply?

I am using a Meanwell SDR-120-12 power supply for a project. I noticed it has terminals for "DC OK" which the datasheet refers to as a relay contact rated for 60Vdc/0.3A, 30Vdc/1A, 30Vac/0.5A resistive load It also says: Contact Close = PSU turns…
JYelton
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Daisy chaining switching supplies

I am utilizing a development board that has an expansion header. The header brings out a 2.5 VDC power rail that is sourced from a buck converter SMPS. I need to use this 2.5 VDC, run it through a boost converter, and generate 3.3 VDC, where I will…
user2913869
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Why does output voltage vary with input voltage at steady state in a switching converter?

All switching converters have feedback which varies the duty cycle so that the output voltage is maintained at a specific voltage. However, the feedback is not perfect and there is still some variance in the output voltage. I am particularly curious…
John Allen
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Switching regulator shortages

This is more of a meta question, so it may get canned. I'm wondering if anyone has any techniques/workflow advice for how to handle the IC shortages particular to switching regulator circuits. For 10 years or so I always used some derivative of the…
Matt
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Paralleling MOSFETs or MOSFET and IGBT to increase capacity in QRSMPS

Is there a relatively simple way to increase the load capacity of a integrated SMPS/MOSFET controller by adding a parallel device? This is the device: Fairchild FSCQ1265RT The method has been successfully used: MOSFET-Assisted Soft-Switching of…
ITPhoenix
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Why do these USB mobile phone chargers have multiple output ratings?

PSU that comes with any electronics device usually has a single output voltage rating. This is because they are intended for use with a single device. These Samsung phone chargers have multiple output ratings! Why is this necessary? How is the…
quantum231
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How to cure SMPS output to get upset by a switching device

I have been having ringing spike issues at the output of SMPS power supplies. I don't know what is this phenomenon is about but it is definitely related to switching devices on the same electrical network. When a switch or switching device is on the…
user1245
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Resistor between Line and Neutral in SMPS

In Below SMPS Circuit ( Credit to:- NXP SMPS Design Tool ), in Red mark what is function of this resistor and why mid point of register is connected to Aux biasing of transformer. Thanks in advance.
techover QA
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What is the need for an inductor coil in a smps-buck converter?

Here is the figure: All tutorials have an inductor in smsp-buck. But when I simulate without an inductor I see a similar plot. Why not use only a capacitor?
user16307
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SMPS (SEPIC) controller in rush current?

I'm designing a circuit that uses a SEPIC controller (LM5022) to switch a power circuit; however, the controller is enabled by a microcontroller and requires ultra-low quiescent current on power down. Initial designs used the UVLO pin to shut the…
Alex Turner
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