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.

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Sizing the DC/DC inductor for only momentary high currents

My DC/DC setup is going to power a GSM modem. The behavior of these modems is that they typically consume only a few tens of milliamps, but when transmitting they are drawing 2A for microseconds. On ...
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Use wirewound resistor as load

I want to use an array of ceramic wirewound resistor in series and parallel as the load of an 80W boost converter with the output of 400volts dc. Is it suitable to use 8 numbers of 10W resistors as ...
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Looking for an AC - DC power supply. Help on specs [closed]

I have been using my old auto stereo amplifier in my home and picked up a meanwell adjustable 0-48V DC. I would like to use a larger amplifier now and would like recommendations for the new supply. ...
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2 answers
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How to check output voltages?

I'm attempting to repair a Dell P2210 PC monitor. I've traced the fault to a faulty diode on the power supply board. As part of the repair I would like to check the output voltages. The service manual ...
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Why is an inductor rather than a capacitor used to smooth switch mode regulators

I understand (at least at a high level) how to use both capacitors and inductors to reduce noise but I don't understand the advantages/disadvantages of each approach or why one is chosen over the ...
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Why don't we make negative output voltage like this?

Here you have a buck conveter where Vout1 = D*Vin which is positive for positive input voltage. I'm wondering why don't we just reverse the connection of output ...
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How does the feedback circuit of this mini USB adapter work?

Summary I came across an old Apple mini USB adapter CLONE. It even had the green dot from the 2008 recall, so it's about a decade old. I'm actually glad I took it apart because one of the prongs fell ...
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6 votes
4 answers
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How to filter out the switching noise from a DC/DC converter

I've set up a power supply using a MAX632 DC/DC Boost converter to bring up voltage from a small 4.5V battery, then I'm using a LM2940CT-5.0 linear regulator to bring it back to 5V, which the voltage ...
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Why don't inverters use BJTs to easily produce a pure sine wave?

This has been in my mind for a while now, I'm curious. Why not use a BJT H-bridge on the high voltage side, to convert the high voltage DC to AC. I saw a simple circuit that converts square waves to ...
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What are the ways to test a switching IC like TOP266EG with a multimeter? [closed]

What are the ways to test a switching IC TOP266EG with a multimeter? I want to check it if it is damaged or not of course. Link to the datasheet. Here is the datasheet picture: Here is the appearance ...
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Are SMPS (inductor) current limits mostly thermal?

I'm building a boost converter that needs to boost 200A for 1 second and then shut down. The vast majority of reading I've done on SMPS and various PSU topologies assumes an RMS current and high duty ...
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For a switching boost regulator, will putting the inductor on the bottom side of the PCB cause issues?

I'm working on a 6-layer PCB with dual-side component placement. To help assembly, I'd like to keep all of the "large" components on the bottom side of the board. One of those large ...
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determining the Bmax for inductor design

at this moment of this youtube video following graph is presented for selecting the proper maximum flux density. the considered proper amount of core loss is 100mW/cm^3. is this a general amount for ...
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2 votes
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What are the differences between these ferrite cores?

The ER, EC, and ETD ferrite cores are presented in a datasheet but visually I don't see any difference between them. The search results also say the same thing.
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Boost LED driver layout check [closed]

I'm designing a 1.5V(alkaline battery) supply 700mA LED driver using PAM2803. The pin assignment is a bit awkward and there's no layout example. I'm new to SMPS and I want to make sure there's no ...
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Range of transformer Q variation for UC3844B converter?

Here the UC3844B High Performance Current Mode Controller (at left, SO-8) is used with a custom transformer to step down bus voltage to 24V. The transformer is likely rated for about 40W, so ...
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Can VCC be supplied by external power supply?

I've implemented the following 80W PFC boost pre-regulator presented in the following application note. I built the inductor and its auxiliary winding myself with another magnetic core and its ...
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Using fuse during initial tests?

I've implemented the presented 80W PFC boost pre-regulator in the following application note without using the applied fuse at the input. Surely I will add the fuse to the finalized tested circuit. ...
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6 votes
3 answers
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Why does a flyback converter in DCM mode have a different oscillation waveform at start and end of MOSFET turn off?

As seen from the waveform, when the MOSFET turns off, it has some high-frequency oscillations (shown in red) whereas before MOSFET turns on it has low-frequency oscillations. I have found that the ...
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2 votes
2 answers
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Synchronous Buck Converter - PWM modulation

Let's say that our Vin = 9V, Vout = 5V. Hence our duty cycle D = 5/9. Let's say that our switching frequency is 100kHz. Consider T_on as the time the HSFET is on. So our T_on in this case is: T_on = (...
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TFT-LCD VCOM powered by LDO

Is it possible to generate VCOM voltage for TFT-LCD display by LDO? I am considering using MAX16929 for generating AVDD (9.6V), VGL (-6V), VGH (18V) and VDD (3.3V) for touch controller, but remaining ...
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How to calculate waste heat dissipation from a DC-to-DC-to-DC conversion

I am wondering how I can calculate the total combined heat dissipation (in watts) by two DC-DC converters in the following scenario; In my case, I have a project where I have 12 volt DC, which gets ...
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1 vote
2 answers
74 views

How critical is the sense resistor?

In the following topology, two 0.68 ohm resistors are paralleled to result in 0.34 ohm for sensing the source current. Can I use three paralleled 1 ohm resistors to result in 0.333 ohm? Does this ...
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2 votes
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implementing dot convention

in the following topology, a boost inductor with secondary winding is operated in which the windings are in opposite directions. Implementing this structure, in reality, made me confused. Based on my ...
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Difference between air gap calculation in an inductor with respect to practical measurement

I've designed a 75 μH inductor with EI3329s. Winding is 23 turns of two parallel 1 mm wire. From calculations, rhe air gap must be 1.1 mm in the center post of the core. I've neglected the reluctance ...
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1 answer
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System blocks of switching power supplies

I want to design my own power supply. I know it can be dangerous for someone whit not much of experience, but at least I want to learn it on the paper! I am aiming for a 12 V/10 A (120 watts) DC ...
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Types of air gaps

I read the Transformer and Inductor Design Handbook and I have some question would like to ask you guys. Why are the EE or EC cores shown in Figure 1-30B the bested suited? Why is only Figure 1-30B ...
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Step-Up Converter Design

I am trying to design a step-up converter with the following specifications: Vin: 3.0 - 3.7 V Vout: 30 V Iout(max): 50 mA With such a high boost ratio, my calculated duty cycle would be ~92% which ...
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Problem with synchronous buck converter

I’m doing a synchronous buck converter using half bridge driver IR2109 () to step down 200 VDC output from my PFC circuit to around 80VDC. I made a PCB and tested out with Vin = 12 VDC, pulled the (SD)...
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2 votes
3 answers
239 views

Boost converter inductor calculation

I am designing a boost converter with the following parameters: Vin: 3.0 - 3.7 V Vout: 30 V (nominal) Iout(max): 10 mA Fsw: 600 kHz TI's application note has the following equations for boost ...
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Can I replace the ceramic capacitor with tantalum?

In the following topology, a 2200nF multilayer ceramic capacitor (SR305E225MAR) is used in the compensation network. Can I replace it with a tantalum capacitor with equivalent voltage and capacitance? ...
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2 votes
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Limiting cold-start current of an SMPS by an NTC

I'm using this SMPS (12 VDC, 12.5 A model) and in my application in steady state the SMPS draws much less than one ampere from the AC line. But as you see its datasheet mentions its cold-start (inrush)...
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Any issues wiring high power switching power supplies to 3 phase power this way?

I have to wire several high power loads to a 415 V 3 phase feed. In case it matters, this is in Singapore. The loads have a switching power supply front end. They are rated for 277 to 480 VAC and ...
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1 vote
1 answer
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Point-to-point building of medium- frequency circuits, ground plane implementation

I build audio projects and small logic control circuits using point-to-point on perfboard (see pic of a recent build). As you can see this allows me to select wire gauge in accordance to the currents ...
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Switching regulator voltage issue after rework

A switching regulator (TPS63030) on my power management board is showing a weird problem after I opted to re-adjust the voltage output. Note that this particular board has been used successfully in ...
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12V to 3.3V using LM3489

I ran into an issue with the LM3489 not actually attempting to switch the transistor at all. I'm not sure why it won't start up. PGATE sits at 12V, VCC and when watching it seems to make no attempt to ...
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-1 votes
1 answer
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High current flow in voltage regulation using TL494

I am using the given schematic for voltage regulation. When I’m not given the feedback, that is point A and B is not connected, then m getting a pulse of 35 % duty cycle of 0-12 V. But when I’m ...
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Synth PSU ripple/noise filtering

Noob alert. I'm building a modular synthesizer (musical instrument) and I'm having a problem with building a good power supply for this use. I bought a +12/-12 VDC power supply and read that ...
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Bridge Rectifier Problem or something else?

I am designing a 30V 5A power supply and after simulations working fine I decided to make it on actual hardware. But during the first run, something shorted and the power supply didn't even turn on. ...
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Flyback Cross-Regulation

The document "Under the Hood of Flyback SMPS Designs", talks about the cross-regulation (on page 8). I have some questions about that. 1.) In what condition the primary voltage will ...
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2 answers
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Flyback leakage inductance effect

The document "Under the Hood of Flyback SMPS Designs", talks about the leakage inductance effect (on page 6). I have some questions about that. The below questions are from fig 5. Why high ...
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-1 votes
2 answers
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parallel boost converter for more current [duplicate]

I have a boost converter that takes 3-5V at input and outputs a steady 5V (This one : https://aliexpress.com/item/33046073847.html). I plugged it to my 18650 battery cell so that I can power an ...
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Flyback CCM right-half-plane-zero and control question

The document Under the Hood of Flyback SMPS Designs, talks about the RHPZ effect. I have some questions about that. 1.) Why do we need to design in the low input voltage and maximum current? 2.) I don'...
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CCM Boost PFC avg rms current

I follow the "Fundamentals of Power Electronics-3rd Edition" to derive the below equation. Now, I would like to derive the Transistor Average, , and I follow the book formula, but my answer ...
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MOSFET switching loss calculation

I read the "PFC boost converter design guide" There is an equation that is used to calculate the switching turn-on loss. Does anyone know how to get that equation?
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CCM boost PFC rms current ca;cu;ation

Does anyone know how to calculate the Boost PFC rms current. I read the "Fundamentals of Power Electronics", there is a formula but I can't total understand. 1.) How to get the red part ...
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-2 votes
1 answer
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Flyback transformer parameters - Inductance [closed]

I am designing a power supply (flyback SMPS) with universal input (120 - 240 VAC) and 6 V @15 A output (90 W). For this purpose, I have shortlisted the pwm switcher NCP1219 - selected because it doesn'...
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2 votes
1 answer
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Mitigating FET current spikes in an SMPS buck converter

I'm currently designing an SMPS buck converter that converts 311VDC to 60VDC at 10 Amps maximum load. I'm using ESP32 for the PWM control, and IR2110 for the switching driver. The switch I'm currently ...
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3 votes
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GaN Vs IGBT performances

I was making some research on GaN and I do not understand why GaN is so reveolutionnary. When I take a look on the following specification RdsOn and Coss (Cds + Cgd), the GaN semiconductor has lower ...
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ATmega freezes because of power supply

I'm using a 10W/12V PCB mount SMPS for a project. In the same board I'm using an ATMEGA2560. When there is a power fluctuation, the ATmega freezes and all the communication is halted. How can I fix ...
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