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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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62 views

I need help to identify this old SMD device

I'm working on a circuit and I can't find information on this component (see picture). This hybrid circuit is part of an old industrial PSU. It is a PFC circuit based on UC3854 but I don't know if the ...
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1answer
23 views

Forward converter input current

I'm trying to calculate the Forward converter's efficiency. For that I calculate the losses, trying to include as much factors as possible. To calculate the loss on the input capacitor's ESR, I have ...
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1answer
37 views

Burst mode in synchronous buck converter with current mode control?

I read this previous question: The meaning of Burst Mode It says burst mode happens when the resistance of the load is light and the system stops switching the MOSFETs. However, I just cannot ...
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27 views

volt-second balance and capacitor charge balance [on hold]

can anyone help with understanding volt-second balance and capacitor charge balance please? Im studying dc-dc converters
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1answer
83 views

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 ...
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67 views

How to find out which voltages a power supply outputs? [on hold]

My TV recently broke down and I am trying to repair it. Parts and traces of the Power Supply are damaged so I had the idea that I could replace the internal Power Supply with an external one. But I ...
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1answer
81 views

How to reduce noise in SMPS (Switching mode power supply) circuit

I am just using a reference design of SMPS (from Microchip) to boost input voltage from 12V to 90V as the image below: It's working normally but the problem is the noise at the output of 90V. I ...
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What is the purpose of this transformer winding in the following SMPS schematic?

I am trying to understand how the following PC switched mode power supply works : The way it works in general is OK. What is not clear to me is what is the purpose of the following part in red : ...
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SMPS secondary rectifying diode placed on GND instead of Vcc [closed]

I have designed a SMPS (low noise) and diode is placed on GND instead of normal Vcc . Is there a benefit having the diode placed there instead of Vcc from a noise perspective ? Is it possible that I ...
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19 views

smps power plane

I am designing an ultra low noise SMPS with 4 layer PCB. On the first layer I have components and power traces. On the second layer I have a whole GND plane. My question is: for the 3 plane (power ...
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1answer
44 views

how to design AC line filter for VFD?

I am working on VFD for single phase induction motor. I am rectifying AC 220V directly to DC link capacitor. There is no LC filter from AC mains. There are harmonics in the AC mains. Can you suggest ...
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2answers
42 views

Forward converter with RCD clamp

In case of a Flyback converter, the RCD clamp is supposed to dissipate only the energy stored in the leakage inductance. However, in case of a Forward converter it would dissipate the energy from the ...
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1answer
49 views

RCD snubber vs active clamp

Consider an isolated Flyback SMPS with RCD snubber on the primary side MOSFET's drain. As the drain voltage rises above the sum of input voltage and snubber capacitor voltage, the diode opens and ...
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4answers
235 views

How to convert a wide voltage range (1 V-12 V) to 5 V?

I have an unusual application where the input voltage can vary from 1-12 V DC. This must be converted to 5 V @ ~200-250 mA. Since there are no available buck-boost converters suitable for this wide ...
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2answers
48 views

How do SMPS work on such a wide range input voltage?

I have a 5 V 3 A SMPS which says that it can take input voltages between 100 V and 240 V AC and frequencies between 50 Hz and 60 Hz. How do these work? How can they take ...
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0answers
30 views

Powering a isolated delta-sigma modulator from AUX winding

Newbie to SMPS design here. I'm designing an SMPS and I'm going to measure the current on the primary side using a shunt. I was thinking about using an AMC1304 modulator to retain the isolation. ...
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1answer
93 views

Buck/Boost Power Supply: What happens if we use much bigger Bulk Capacitance (i.e. 10x)?

If we take a buck/boost converter that is known to function correctly, but increase the bulk capacitance by 10x, what can we expect to happen electrically? Background: I took the design below off TI'...
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2answers
60 views

DC/DC Converter Output Power Rating

Looking at chips such as AP6502A TPS5430 The output capability is rated in peak and continuous current. Why are they not rated in terms of power? What output voltage is this current rating for? ...
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25 views

SMD NP0 soft termination or SMD Film capacitor for SMPS filtering and AC switch loop

Hello I have a problem where I've to select a suitable decoupling/bypass capacitor for the AC-path for the switch noise for the 400V switching H-bridge where I need low height of components. Where the ...
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2answers
50 views

Understanding a switched-mode power supply datasheet

I'm trying to make an AC/DC converter (230V AC to 5V DC). As part of this converter, for the first stage, I've decided to use a switched-mode power supply like https://www.digikey.com/product-detail/...
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0answers
68 views

Full bridge driver capacitor ringing problem

This is my first time designing a full bridge driver. I am experiencing problems with ringing on the output. I have made a pcb for it. This is a picture of the top side of the board. Backside Input ...
1
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1answer
41 views

SMPS and pcb layers

I am trying to design a ultra low noise SMPS with 20 W output (85 V to 220 V) and need to make a choice between 4 layers PCB and 6 layers. On the 4 layers we plan on having components on both sides ...
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1answer
40 views

Voltage sequencing on power up

I'm pretty new on PCB design, so my question may be obvious for some of you. I am wiring the layout of an LCD screen on a PCB using kicad, when I came to powering up, the datasheet of the AT070TN92 (...
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2answers
82 views

Grounding a Laptop

I have the following problem: I am currently debugging an electronic sensor board which is connected to the USB port of a laptop. The USB port is used both for communication via UART and to supply ...
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0answers
38 views

How to design a capacitive power supply with 4v battery backup?

I want to make a simple and cheap LED driver with a backup battery on mains failure. The battery (4v Lead Acid) should be protected from overcharging. Problem Would this circuit works? (what are the ...
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2answers
53 views

Calculating the oscillator frequency

I am trying to calculate the frequency of the internal oscillator, in order to go through the design procedure listed in the datasheet. The problem is that it gives me answers that contradict the ...
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1answer
45 views

Noise spikes caused by external AC switching

I have built a circuit that measures time between two 5V pulses. It works good but I'm having problems with voltage spikes that comes from the AC mains. And it triggers the interrupt pin on the PIC. ...
0
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1answer
119 views

How are PWM IC's able to provide so many features in small footprints ? [closed]

If you look at the general pwm IC's for standard topologies (buck, boost etch) , they have tons of protection features such UVLO, overvoltage, cycle-cycle protection and overcurrent protection. They ...
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2answers
60 views

Understanding Vgs absolute value

If a P-channel MOSFET have absolute maximum values: VDSS = -60 V Vgs = +/-20 V "refering to high switch side": Does this means we cannot switch the MOSFET by the gate driver that ties the gate to ...
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0answers
40 views

Under voltage protection with schottky diode, bad or legit idea?

I'm working on a design where I in simulation have discovered that I probably will have problem with to much negative Vgs, so I firstly tried to find a zener diode that could combine both OVL and UVL ...
2
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2answers
46 views

Feed-forward capacitor in SMPS feedback

I was looking at the TPS63700 DC-DC inverter datasheet and stumbled across the schematic below. It is a more or less usual buck-boost inverter topology schematic, except for the weird R4 and C3 ...
1
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1answer
37 views

Is there an industry-wide name for anti-parallel diodes across an IGBT module's collector and emitter?

For example, this datasheet refers to a 'freewheeling' diode and a 'boost' diode. The upper diode is the freewheeling diode, right? If you wanted to switch an inductive load with a single such module,...
2
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1answer
49 views

Zeta topology DC-DC converter unstable

So I've tried to build a Zeta topology DC-DC converter based on a simple buck converter IC XL4016, which works perfectly in a regular buck topology. However, when hooked up in a Zeta topology as shown ...
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0answers
50 views

0402 resistor has a decreased resistance value when connected to a switching voltage node. 0603 size resolves the issue?

I see that the resistance value of a 0402 connected to a switching voltage node changes. When I use 0603 resistor, the resistance remains quite stable.Is there a voltage coefficient to be considered ...
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2answers
864 views

Cuk topology patent

While searching for a good inverting SMPS topology, I stumbled across the Cuk topology which suits me perfectly by all means. The only thing that worries me is that unlike more common SMPS topologies, ...
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0answers
56 views

CRT TV NOT TURNING ON [closed]

I'm a beginner in electronics repairing and I need help troubleshooting a tv which doesn't turt on, neither the power LED lights up. The board is a cheap chinese (check the attached image). When I ...
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0answers
60 views

switching between two similar power sources - solar battery and cr2032

I'm trying to create a circuit powered by two alternative power sources. The first one is a Li-Po battery charged by a solar panel and the second one - standard 3v battery, ie. CR2032. The circuit ...
3
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2answers
87 views

EMC Testing, Radiated Emissions

I recently had one of my new rechargeable Lithium Ion products tested (RE pre-compliance scan) and I had a few frequencies (around 150 MHz) pop (7-10 dBuV/m) above the FCC and CISPR limits. I'm not ...
2
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1answer
68 views

Replace bad voltage regulator with another one that have lower output current

I need to replace a shorted TL750L05 +5V voltage regulator with a new one. The problem is I can not easily find a replacement part that has the same features. I found the LM2931M-5.0 but is rated at ...
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0answers
27 views

Determining Phase Boost needed to Compensate SMPS

I'm attempting to find the Control-To-Output Bode Plot (open-loop) of a SMPS designed around the TPS54160 so that I can design the type II compensator. The first step in designing a compensator is ...
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2answers
53 views

Bipolar switched-mode power supply

I'm looking to design a power supply that, given 24V input, can deliver +/- 0-12V output at 3A. It will be used to drive a Peltier module in either heating or cooling mode, which is why it must be ...
3
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3answers
277 views

caps in series, equivalent capacitance to reduce voltage rating

For example, I need 100uF 60V capacitor for filtering in power supply. DC source is about 40V. But I have 400uF 20V caps. If I arrange four of them in series I got in total 100 uF and each cap has ...
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0answers
27 views

Power supply for electro plating

Which DC power supply will be more suitable for electro plating? The PWM type or the normal adjustable V/I type? How many voltage and current will need to be applied. What parameter to decide how ...
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1answer
82 views

Need help to newbie to understand MIL-STD-461 [closed]

why only 10khz-10Mhz is used for CE102 test ? why not other frequency range is used for CE102 test ?
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1answer
100 views

Controlling the Spark plug using 555 IC

I built the circuit for ignition system using MOSFET, 555, ignition coil(specs unknown. But current rating is more than 2 A and less than 10 A), SMPS(12 V, 10 A for powering the the whole circuit). ...
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1answer
82 views

How do you model differential inductor in LTspice?

I wonder how I can model a differential inductor in LTspice? I've an inductor that has half the turns on one side and the other half on the other side. It's intended to be used in a bridge tied ...
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0answers
28 views

DC DC converter opamp compensation

I have simple doubt. I am making a closed loop DC DC converter flyback, I am using opamp for compensation. It should be a single input single output network. Input voltage is 24-32 volt, output is 5V ,...
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0answers
38 views

Optimal duty cycle in Forward converter?

So as far as I understand the Forward topology: The duty cycle set by the controller in CCM mode is constant assuming constant input voltage and constant output voltage. The duty cycle is independent ...
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2answers
148 views

Vector network analyzer for SMPS feedback loop measurements

Does there exist a ready-made design for implementing the measurement hardware? You can buy the analyzer package from e.g. Omicron Lab but it's a hideously expensive piece of kit (4490€) considering ...
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1answer
40 views

RCC SMPS circuit modify

Its a classic ringing choke converter smps circuit found in chargers. This one yields 240ma @9v, need to modify to get 2A@5v, already have a 5v2A flyback dc dc transformer. Just need the changed ...