All Questions
Tagged with switch-mode-power-supply capacitor
108 questions
3
votes
1
answer
127
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Higher capacitance for EMI return cap in isolated DC-DC-SMPS?
A typical SMPS converter usually includes a small capacitor of ~1 nF in tight proximity to the isolation transformer to return the common-mode switch noise to the primary side switch for EMC reasons.
...
- 23.4k
3
votes
3
answers
292
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Using only ceramic capacitors on an input of an SMPS - unclear advice from manufacturer
I was reading through the datasheet of a boost converter, TPS61023 from TI.
In the "Input Capacitor Selection section", they give the following advice:
Notably, TI advises against using ...
- 572
0
votes
0
answers
70
views
Capacitance Formula derivation
Can anyone help me with how this formula came in the first place (marked in red)? I am not able to understand the denominator term.
This is with reference to Double Pulse Test taken from the book : ...
- 295
0
votes
3
answers
95
views
Charge "something" over a 10 second interval then dump the charge on a load. (Alternative to battery?)
I'm getting a limited current of about 10 mA from a 12 V DC source. I would like to charge "something" (anything but a battery) with this energy over 10 seconds, and then dump it to a 12V ...
- 137
0
votes
0
answers
195
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Why do we need a small external gate to source capacitor for a MOSFET drive circuit?
I have a question regarding a MOSFET half bridge driver circuit. We always connect a small capcitor between the gate and source of both the high side and the low side switch, typically in picofarads. ...
- 357
0
votes
1
answer
116
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Why solid state capacitors?
I've been looking through multiple cellphone chargers and I have noticed that they all use solid state capacitor for the output capacitor of the switching power supply (flyback converter).
Is there ...
0
votes
0
answers
46
views
5 V to 3.3 V buck with limited input current and large capacitor to cover current spikes?
We need to design a power supply for a 3.3 V WiFi-device. But there are quite some current spikes during WiFi startup. Using the design below there is a risk the 5 V (250 mA max) supply (not mine) ...
- 1
2
votes
3
answers
322
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Output stage filter of a buck regulator and ESR
I am trying to design a two LC stage output filter on a buck converter. And as the needed peak to peak ripple has to be pretty low ~ 1 mV, the overshoot and undershoot need also to be pretty low, I ...
- 2,610
2
votes
2
answers
504
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How can you calculate Peak Pulse Power for a Non-Rectangular Power Pulse
I was reading this Vishay document on how Peak Pulse Power can affect resistors.
There is a flow which is attached in the document describing the process of calculating the Peak Pulse Power for a Non-...
- 23
3
votes
2
answers
615
views
What is the role of an MKP capacitor in the input of this SMPS? What happens if I remove it?
I'm trying to repair this SMPS board. It converts 220VAC into 15VDC. The circuit is based on KA5L0380R power switch.
The input 1A subminiature fuse of the circuit is blown. To find other broken ...
- 73
7
votes
4
answers
1k
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Derating of C0G DC block capacitors with applied DC voltage
I was having a discussion with a colleague at work regarding derating of MLCC capacitors when used as a DC block capacitor. My colleague mentioned that it is standard practice to derate MLCCs with the ...
- 489
2
votes
1
answer
167
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Output Capacitor Design for a Multiphase Buck Converter
According to this application note from Texas Instruments, in the design of the output filter for a multiphase buck converter there are basically two ways of choosing the output capacitor. The first ...
5
votes
2
answers
743
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What is the purpose of the capacitor in this SMPS circuit?
Can anyone tell me the purpose of the 2n2 100V capacitor and its function in the circuit?
Image source: danyk.cz - 12V 5A switched power supply
- 51
1
vote
1
answer
81
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Duty Cycle and Filtering in Switching Power Supplies
I have a few confusions to clear up. The first one is about the switching power supply.
Does the power supply simply work on the bases of the duty cycle? Like If I have a pulsating signal of 50% duty ...
- 693
0
votes
1
answer
106
views
When finding ESR/ESL of a ceramic capacitor, what frequency should I assume during a load step?
I want to determine the output droop in a transient load step for a buck converter I am designing.
The output capacitor will supply current during this load step, and there will be a drop associated ...
- 346
3
votes
2
answers
628
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Half bridge SMPS with polypropylene film capacitor
I dismantled a cheap Chinese 240VAC to 48v-20A SMPS to try to understand the basic working principle.
There is a CBB22 335J630V polypropylene film capacitor in it. I have drawn it in red on this basic ...
- 349
0
votes
1
answer
165
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Non-isolated DC/DC converter
I am integrating a non-isolated DC/DC converter from Mornsun in one of our designs.
We are trying to stick to the typical application schematic:
However, two questions dictated by the limited space ...
- 445
1
vote
3
answers
197
views
Different type of capacitors
How can I distinguish between filter capacitors, decoupling capacitors, and bypass capacitors? What is the most basic and important difference in their functionality?
- 357
0
votes
1
answer
42
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Purpose of non-polar C1 - R1 in series
what is the purpose or function of series non-polar C1 - R1 (24 Ohm resistor) on parallel to rectifying D around SMPS output here ?
Help clarify by elaborated explanation, thanks
- 399
1
vote
1
answer
439
views
What is the purpose of adding series resistor to tantalum capacitors?
For a power rail, we have used tantalum polymer caps whose ESR is as low as 50 mohm.
I see that a few of these capacitors have a 1 ohm resistor added in series, a significant value.
What could be the ...
- 3,156
1
vote
2
answers
104
views
What is the frequency at the input of the bulk capacitor in a flyback?
I am under the impression that the output frequency of the bulk capacitor will be the same as the switching frequency of the PWM chip. The input however I am a bit confused about, because if it is ...
- 127
2
votes
1
answer
2k
views
What is the function of the feedforward capacitor on the LM2596-ADJ?
I'm looking at the LM2596S datasheet and notice that on page 7 (figure 3) it recommends a "feedforward" capacitor for the adjustable variant.
The example schematic on page 9 shows a ...
- 11.1k
0
votes
1
answer
371
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A ceramic capacitor on my PC SMPS has blown; need to identify it [closed]
I have a Cooler Master 600 W SMPS Model no. RS-600-pcar-E3. Recently I tried to switch on my motherboard and I heard something burst and saw sparks before it stopped working.
After opening it I got a ...
- 9
0
votes
1
answer
42
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Choosing output capacitor for Power converting Switching regulator (Cout_Eff)
I am using R1276S001A-E2-FE to convert my 24 V supply to 3.3 V to power my microcontroller.
In order to do the conversion properly I need to choose the output capacitor. I see there are three ways to ...
- 59
0
votes
1
answer
1k
views
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 ...
- 263
0
votes
1
answer
243
views
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? ...
- 755
1
vote
1
answer
271
views
SMPS bulk capacitor number
I am designing a SMPS and calculated the input capacitor to be around 47µF. The voltage rating needs to be >1000V.
What would be the difference (advantages/disadvantages) between using 2x500V in ...
- 505
2
votes
3
answers
601
views
X2 polypropylene capacitor for DC smoothing after AC rectification
Can a X2 polypropylene film capacitor be used for dc smoothing at the output of a bridge rectifier? I want to use this capacitor at the input of a power factor correction circuit with a switching ...
- 101
0
votes
0
answers
98
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What is a Ladder Switched Capacitor?
I have recently read several papers with LSC on it (I'm taking care of my Mom 24/7, so I can't find them right now). Are Dickson and Cockroft-Walton considered Ladder, or am I off? Thanks.
- 2,980
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0
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94
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Must a 12V to 110V switched-capacitor inverter output be isolated? if so, does anything special have to be done?
I have an LTSpice simulation of a small switched-capacitor boost converter producing about 12W x 110V of DC, and I was wondering, does it have to be isolated (and need anything special to attain ...
- 2,980
4
votes
3
answers
673
views
Ceramic capacitors shorting on power up
I have a power supply unit that is used to drive a couple of relays. Rarely but sometimes the input capacitors (C218, C200, C201 and C207) to the switch (U202) short when the power is turned on (230V.)...
- 41
1
vote
1
answer
514
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For calculating inrush current in a ceramic capacitor , do we need to consider the effective capacitance after derating for dc-bias effect?
Inrush current happens when capacitor is initially charged from 0V to the intended rail voltage.
What should be the effective capacitance to be considered during this charging? -Since the voltage ...
- 3,156
0
votes
1
answer
107
views
Feedback loop design (buck converter): Output capacitance- effective value or nominal value to be considered?
In this TI datasheet of TPS62180, it was mentioned that the LC filter combination should be selected from a set of predefined values. I understand this is usually the case for an internally ...
- 3,156
1
vote
1
answer
80
views
Why is the input capacitor calculation different in TI datasheet?
Below is the input capacitor calculation from TI datasheet
Why is it different from standard buck calculation given below?
Another TI dcoument
- 3,156
0
votes
1
answer
211
views
Prevent spark/surge when connecting power cable (charging input bulk capacitor)
In cheap off-line AC-DC SMPS you will probably notice a huge spark when you connecting the PSU to mains. That usually won't cause problem because your mains is far more capable to handle that surge.
...
- 429
1
vote
2
answers
171
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Charge pump circuit- What is the need for caps near CLK pin?
Below is a charge pump circuit in NB680 IC Datasheet
I was trying to understand the charge pump functionality by comparing it with the standard circuitry shown below:
https://www.edn.com/capacitive-...
- 3,156
1
vote
1
answer
2k
views
Capacitor blows up in TV power supply circuit
I have an LED TV Samsung T22B350EW (Type No.: LT22B350) which can not power on. I'm trying to fix it, to learn more about such type of circuits. A capacitor in its power supply board is blown up.
The ...
- 748
1
vote
3
answers
777
views
Following is an excerpt from a power electronics textbook. Is the statement true?
As far as I know ESR primarily depends on the type of dielectric.
eg: Al electrolytic (higher capacitance value) would have much higher ESR than ceramic (usually lower capacitance value).
Say for ...
- 3,156
-2
votes
1
answer
75
views
How will this circuit work [closed]
This circuit is after the rectification process how will this work
1
vote
0
answers
96
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What type of SMPS is this?
What specific type of SMPS is this? I'm working on troubleshooting no power out.
I'm having trouble finding comparable circuits so I can learn how it works. It appears to be some sort of resonant ...
- 67
0
votes
0
answers
148
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how this equation is obtained for calculating input capacitor of a fly back presented in UC3842 datasheet?
i know that it refers to stored energy formula for a capacitor according to voltage variations. but i dont have any idea about the specified part. where did this part come from?
https://www.ti.com/lit/...
- 755
0
votes
0
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167
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Can a MOV properly discharge a X-Capacitor?
I created an AC-DC SMPS with a EMI filter that consists of a X-Capacitor and Common-Mode Choke. IEC 62368-1 requires that capacitors be discharged below ES1 (60V) within 2s of being disconnected. As ...
0
votes
1
answer
167
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Determining capacitor value in a flyback converter
I have a dead audio mixer power supply (Soundcraft MTK 22) which I am trying to bring back to life and learn more about flyback converters in the process. This particular supply runs on 230VAC and ...
- 3
0
votes
1
answer
298
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Is a SEPIC converter truly isolated?
I have been in two separate design reviews where the SEPIC topology was rejected for an isolated < 40W application. These meetings were at 2 different companies and with different principal ...
- 1
0
votes
0
answers
41
views
Need some suggestion on 220 - 3.3 volt 500 mA power supply (Or 12 volts maximum)
I was planning to make some 220-3.3 volts,5 volts & 12 volts power supplies. I tried the configuration above in proteus (0.47uF, 275 volts RMS, Polypropylene film capacitor in series with a small ...
- 2,519
1
vote
1
answer
264
views
Where to connect Y capacitor with a low side switching element?
I was working on a power adapter, and we had a synchronous rectifier in the positive high side rail.
We have a Y capacitor between primary ground and secondary ground - between "A" and "...
- 167
0
votes
0
answers
224
views
Estimation of Electrolytic Capacitor ESR at SMPS Frequencies
While working on compensation networks or ripple calculations, it helps to know the ESR for my output capacitors. In high voltage SMPS systems, this seems to be difficult for the following reasons:
...
- 3,586
0
votes
3
answers
915
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Role of the output capacitor in buck converter in terms of frequency
I am using this DC-DC buck converter - buck converter.
Schematics :
Buck Converter Specifications :
Input Voltage - 18V to 32V
Switching Frequency - 300kHz
Output Voltage 9V
Load Current - 0mA to ...
user220456
2
votes
0
answers
307
views
SMPS powered DC motor inrush current problem
I stumbled upon a problem when connecting a DC motor to a SMPS. It's a 20W AC/DC converter with an 12V output that powers some 12V DC motors the processor and some LEDs. I needed to speed up the most ...
- 45
2
votes
2
answers
446
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Voltage rating and tantalum vs ceramic capacitor on the output of a switching voltage boost stage
I am designing a PCB with a TPS61090 synchronous boost converter. The datasheet recommends a ceramic 2.2uF and a tantalum polarized capacitor on the output of the chip. They discuss calculating the ...
- 155