Questions tagged [switching-losses]
The switching-losses tag has no usage guidance.
66
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Which has better efficiency: step-up or step-down switching voltage regulator?
I have a Lithium battery pack circuit that converts 4.2V (two 4.2V cells in parallel) to 5V.
Another option is to use a step-down converter from 8.4V (two 4.2V cells in series) to 5V.
Considering ...
15
votes
4
answers
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Difference between High- and Low- side switching of power?
Is there any real difference between high- and low-side switching?
Assume:
Switching is for on/off control of an object (My case RPi)
Base/Gate can be driven to Vcc and GND
11
votes
4
answers
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How to increase mosfet switching speed, and decrease switching losses?
I hope this is not a too broad question, but what are the best practices to achieve fast switching on a MOSFET driven by a PWM signal?
My current knowledge tells me I can do two things:
1 - To use ...
10
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3
answers
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Dual active bridge converter
I'm having issues calculating the power losses associated with the operation of a bidirectional isolated dual active bridge DC/DC converter. The converter is controlled using phase shift modulation (...
9
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2
answers
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How to determine maximum PWM frequency for transistor (2SK2554)
How can I determine (estimate) maximum reasonable PWM frequency for 2SK2554 transistor?
I found timings in datasheet:
I could estimate frequency from this (and make sure that all these times are 20-...
8
votes
1
answer
5k
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How to determine BJT switching time
Is there some standard way to get information about BJT (Bipolar Junction Transistor) rise and fall times (the high power ones) ? In essence a IGBT is a BJT being driven by a FET, so there should be ...
5
votes
1
answer
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What are the implications of a MOSFET not listing switching losses in the data sheet?
Many MOSFETs do not specify switching losses in their data sheets. Does this imply that the losses are too low to worry about? Too high for the device to be used in a switching application? Variable ...
5
votes
2
answers
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Speeding up turn-on and off with VOM1271 Photovoltaic MOSFET Driver (/optocoupler)
It's my first post here so please do not hesitate to tell me if I'm not doing it right :-)
A bit of context : we need to switch an array of power resistors (1,3kW, 1ohms) in order to test under load ...
4
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2
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synchronous buck ls-FET switching losses and dead time minimization
I'm designing a Synchronous buck converter. I'm having doubts regarding the following:
In the rectifying period of the converter, using a Schottky diode in parallel with the low side MOSFET will ...
4
votes
1
answer
776
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MOSFET fast turn-off not enough
I have a PWM bridge driving a higher than 1k load from 200V supply. The simplified, equivalent schematic is this:
The drivers I'm using are slow turn-on/fast turn-off and, in the schematic, it's a 50%...
4
votes
1
answer
117
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Push-Pull DC converter - resonance in the waveform
I'm building 48v to 200v Push-Pull DC converter.
And now I'm close to finishing the project, but when I checked the waveform on the transformer I discovered that it looks like this:
(on this picture ...
4
votes
0
answers
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How to determine Vds(on) and Vds(off) for switching loss calculation?
In the Infineon Application Note, two of the parameters they've used to calculate the switching loss of the MOSFET are Vds(on) and Vds(off).
Is the Vds(off) the blocking voltage?
Where do they obtain ...
4
votes
1
answer
11k
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Calculation of diode switching losses
I am an Electrical Engineering student.
I'm in my final year and doing a thesis about soft switching.
I am trying to grasp the calculation of diode switching losses. I'm having the impression that ...
3
votes
2
answers
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Why does this circuit speedup the switching time and reduce losses?
I am a little confused as to how this circuit works:
According to this website its function is to speedup charge time of the MOSFET as well as reduce losses. How does D1 and Q2 actually work to make ...
3
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3
answers
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Does body diode reduce MOSFET switching loss in a power converter?
In power converters, it is common that MOSFETs are fed a PWM signal to have cyclic switching. Part of the power is lost in the process. Does the body diode reduce this loss? It seems most power ...
3
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2
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Switching loss calculation formula
I read an article talking about the power switching loss formula, and I am curious about one thing.
How to use math to prove the 1/6 and 1/2 in these two waveforms? Could someone give me some idea?
3
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2
answers
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Measurement with High Voltage Differential Probe
I am doing a measurement with this a 100 MHz high voltage differential probe with voltage derating. As per datasheet of TT-SI 9110 probe, the derating curve looks like below.
What impact this voltage ...
3
votes
1
answer
675
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How to calculate thermal heat from a switching voltage regulator?
I found this answer here which explains how to calculate the watts that are dissipated in a switching voltage regulator, but once you calculate the watts dissipated how do you know how much ...
3
votes
1
answer
2k
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PWM motor heating
Every man and his dog are controlling DC motors with PWM. Nowadays microprocessors are popular and offer more flexibility than 555 timers and general mixed signal analog electronic. The song remains ...
3
votes
1
answer
142
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SEMIKRON: Effect of gate inductance on Eon (Switching losses)
I was reading the AN1403 "Determining Switching Losses of SEMIKRON IGBT modules" from SEMIKRON.
https://www.semikron.com/service-support/downloads/detail/semikron-application-note-...
3
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1
answer
249
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Problems sharing data on a common uSD between a camera and micro; - Switch (TS3A27518E)
We are having a lot of difficulties sharing a uSD card between two devices (an Atmel micro which uses the SPI, and a camera). We used to do this using relays, and all worked fine, but cards got faster ...
2
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1
answer
327
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In MOSFET switching loss calculation, where does the 0.5 factor come from?
I am going through this material for calculating the switching loss of the mosfet.(https://www.monolithicpower.com/frequency-selection-in-switching-power-supply-designs-part-i)
The switching loss ...
2
votes
1
answer
195
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How does the buck regulator soft start condition reduce the unwanted voltage drops from high impedance power sources?
I have been studying the functionality of the soft start function. I understood how it will help to reduce the overshoot of the output voltage as well. Here, my intention is to understand the meaning ...
2
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2
answers
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Can a thyristor regain its forward/reverse blocking capability if the current through it is "instantly" brought to zero?
I am imagining a situation where we have several series-connected thyristors, say 10, each that can block a voltage of 100V. So, the ten series-connected thyristors together can block a total voltage ...
1
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3
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4k
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Baker Clamp application for PNP Transistor
I have an issue related to Baker Clamp application for PNP Transistor. I know how to implement the Baker Clamp for NPN Transistor. However I do not know how to do it for PNP. So could anyone can ...
1
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2
answers
422
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Lower duty cycle less efficient?
Assume you have a DC voltage V, ideal switch (no switching losses) operating at some frequency f and duty cycle ...
1
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4
answers
4k
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Why are switching losses proportional to switching frequency?
Actually in soft switching converters an increase in frequency increases switching losses?
Can anyone explain why?
1
vote
2
answers
282
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MOSFET Selection criteria considering conduction losses, switching losses and working frequency
I am trying to choose a suitable MOSFET for my full-bridge resonant converter for wireless power transfer. The circuit topology is something like the following. Specifications: rated power \$-~500 W\$...
1
vote
1
answer
88
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How to calculate the switching loss of an OR Gate?
This is the datasheet of the OR gate. Current consumption as per the datasheet is 25 uA. (Electrical Characteristics table - Page 4
Input current Icc = 25 uA).
I am wondering how power consumption ...
1
vote
1
answer
4k
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Is there a formula to figure out power loss of a power inverter?
Is there a formula that will give me a ball park idea of how much power I will lose when I run my DC battery bank through a power inverter? Is this something that varies depending on the inverter? ...
1
vote
1
answer
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How to use "voltage controlled switch" in OrCAD?
In this OrCAD project, I tried to build a really basic DC-DC converter with use of "S" or "SBreak" parts in OrCAD's Analog Library. But, according to analysis (picture below), the ...
1
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1
answer
370
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Does supply voltage affects stepper motor driver heat dissipation?
Below is a block diagram of a stepper motor controller with an external mosfet h-bridge that drives one of the stepper's coils. Let's say that the coil has 2ohm DC resistance and 3mh inductance, the ...
1
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2
answers
4k
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Dynamic and Active Leakage in CMOS
I studied various techniques to reduce the leakage power consumption in CMOS design. Leakage currents can be static and active.
I understand the meaning of static (standby) leakage, but I am ...
1
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1
answer
472
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Is 0.5CossVdc^2 included in Pswitching losses of MOSFET?
This document (page 3) from TI states that switching losses of a High Side (HS) MOSFET (of a Synchronous Buck Converter) are:
Then is states that another part of the mosfet losses are:
which ...
1
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1
answer
203
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Strange behaviour while simulating switching loss
I am trying to simulate gate charge profile and switching loss curves of transistor as in the circuit below. I used ideal current source (30uA) for load, clamp diode (piecewise-linear model with ron = ...
1
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2
answers
9k
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Diode losses in switching power supply
I couldn't find a simple approx formula for calculating diode reverse recovery losses!
I am not doing any rocket science, so I just need an approx formula (not worried much about temperature effects ...
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0
answers
350
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Reverse recovery body diode in synchronous buck converter
I am building a synchronous buck converter from 72 V to 4.2 V 2 A. Is there a way to lower the losses of the lowside MOSFET’s body diode? I am using a switching frequency of 300 kHz and with the ...
1
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0
answers
227
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Can a voltage peak detector circuit detect square wave overshoot voltage?
I'm building a simple inverter with an inductive-capacitive load.
I wonder if I have overshoot voltage like this on my IGBT:
I want to detect this overshoot, but since I don’t have an oscilloscope I'...
1
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0
answers
311
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High efficiency pwm current limiter for charging supercap from alkaline battery
I'm designing device which uses two alkaline C-batteries in series as power source, and sends SMS messages using SIM800. On average 1 message per day is sent. Goal is to maximize battery life.
Allowed ...
1
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0
answers
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Is zero loss turn-off possible for thyristors?
Consider this very basic circuit:
simulate this circuit – Schematic created using CircuitLab
Don't mind the values - they don't matter, as this question is conceptual.
Imagine that Vcomm is ...
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0
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MOSFET switching losses in LTSpice
I've made a simulation of three-phase MOSFET rectifier in LTSpice. I am simulating different conduction angles and calculating efficiency. However, I would like to also take a look at the switching ...
0
votes
2
answers
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Any advantage in AC-DC or DC-DC with past, large form factor semiconductors?
I want to clarify this question with my real-world example:
Say you have a device which contains some AC-DC converter (or DC-DC) for rather high power specs (10 kW up to 300 kW, not in the same ...
0
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2
answers
222
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Power loss of MOSFET
How can I calculate the power loss of a dpak Mosfet after adding thermal vias around it?
I added a 14x7 matrix of 0.5mm THT vias with in between distance of 1.3mm to relieve the thermal stress around ...
0
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1
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Flyback diode choice
I am curious about how to determine the turn ratio to get the minimum power loss. Assuming n=Np/Ns Vin=380, Vo=40, different turn ratios can get the same output because Vo =VinD/(n(1-D)).
When the n ...
0
votes
1
answer
63
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Efficiency curve of synchronous DC-DC controller with external MOSFETs
I'm designing a 48V to 12V, 300W buck converter. I am considering using the LM5148 controller and NTMFSC004N08MC switches. I'm confused about how synchronous DC-DC controllers can list efficiency ...
0
votes
3
answers
910
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N-Mosfet switch circuit strange behavior laboratory power supply
I'm dealing with an N-Mosfet switch circuit to control, through PWM, the temperature of a heater resistor. The mosfet is a IRFS7430-7PPBF.
The load is driven at 12V and has a power rating of 80W.
...
0
votes
1
answer
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Why is an LLC converter designed to operate in the ZVS region? how does the Resonance in the LLC circuit contribute to low "MOSFET losses"?
For the first question I understand that operating in the ZCS region can result in shoot through but why does that happen?
I understand that an LLC converter uses the leakage inductance of the ...
0
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1
answer
261
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IGBT Turn-on switching energy loss
I found this formula to calculate \$E_{\text{on}}\$ for an IGBT:
$$E_{\text{on}} = \int\limits_{t_1}^{t_2}p_v(t)\text{ d}t = \int\limits_{t_1}^{t_2}v_{CE}(t) \times i_C(t)\text{ d}t$$
How can I ...
0
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1
answer
193
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Junction temperature calculation
I have a question regarding the calculation of the junction temperature of MOSFETs and IGBTs.
An estimation is possible with:
$$T_j = P \times R_{th} + T_a$$
Let us assume that the thermal resistance (...
0
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1
answer
560
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Linear power supply vs SMPS (losses in transformer)
We know that, in a power supply, there are always losses taking place.
If we have a linear power supply, the major source of loss is the core loss in the transformer.
But in an SMPS, where we have a ...