All Questions
Tagged with switch-mode-power-supply buck
312 questions
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Buck/boost inductor design calculation
I am designing a buck/boost converter with the following parameters:
Vin: 2.5 - 4.2 V
Vout: 3.3V
Iout Max: 1A
Fsw: 1250Khz (From Dtasheet Page 3)
Mine is a battery powered application.
The inductor ...
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0
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0
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31
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Buck Average Modelling
I completed average modelling with Voreperian PWM switch model as described in Christophe Basso's book "Transfer Function of Switching Converters" and I compared the average model with ...
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0
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1
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125
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Buck Converter Peak Current Mode Control Average Model
I am trying to understand average model of Buck Converter for Peak Current Mode Control Topology.
Below snapshot taken from Christophe Basso Webpage(https://powersimtof.com/Spice.htm) from file "...
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0
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0
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63
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Current sensing in DC-DC converter
I studied DC-DC converter in peak/valley/average mode control and I have a question about the methodology to sense the current in average current mode control. I saw lot of paper about DCR sensing but ...
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2
votes
1
answer
118
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Peak current mode control loop compensation calculations
I recently came across a rather nice straight-to-the-point application note by RickTek (AN028) on how to calculate approximately the compensation network of a PCM buck regulator.
Link : https://www....
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4
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4
answers
625
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Inductor energy storing in buck converter
I am trying to understand inductor energy storing during ON time in buck converter.
Energy stored in inductor of buck converter is (Input Power -Output Power)*Ton
Lets say output power is 5 W and ...
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5
votes
2
answers
315
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Non inverting buck boost transfer function
When considering the compensation of a non inverting buck boost (single inductor), the datasheet considers to take into account the worst transfer function between the buck transfer function and the ...
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15
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3
answers
2k
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Why did my DC/DC Buck Circuit fail?
I'm in the process of debugging a PCB I made. On this board, a 24V input feeds through a DC/DC buck circuit (based around the TI TPS54202DDC) to output 11V, then an LDO to output 9V (to ensure a very ...
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1
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1
answer
291
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Average Modelling of Buck Converter
I am doing Modelling of Buck Converter for LT3890 (Datasheet link attached) for Frequency response analysis .
I have some reference model of Buck converter ,please refer below image
Datasheet Link: ...
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0
votes
2
answers
189
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Power Converter Average Modelling
This image is from Christophe Basso presentation. It has been mentioned in the slide that average model can predict the transient response but I have one question when we say average model then it ...
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7
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2
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779
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How do buck regulator modules with integrated inductors manage to be so small?
This 20 A buck regulator module from TI is 6.5x7.5x4 mm and has an internal 330 nH inductor.
This 6.5x6.5x3.1 mm 330 nH inductor from Coilcraft has an RMS current rating of 18.8 A and is the smallest ...
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0
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1
answer
70
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Schematic review MAX20029ATIAV
I am using a MAX20029ATIAV in my design for powering a Quad Tunneling GMSL2/1 to CSI-2 Deserializer.
MAX20029ATIAV is Quad Low-Voltage Step-Down DC-DC Converters.
My schematic is given below. May I ...
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0
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0
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65
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Best power supply configuration
I'm making a power supply board with a buck converter for a 2A maximum and I would to know which is the best configuration between these two:
Is it best to put the input filter, a parallel damped LC ...
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3
votes
3
answers
1k
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Input impedance of a buck converter
Is there an approximate formula for calculating the minimum value of the input resistance (or impedance) of a switching regulator? I found several formulas but can't figure out which one to choose. I ...
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46
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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) ...
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3
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329
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Does DC-DC 24V-12V waste less power than AC-DC 220V-12V?
I am modifying an existing UPS to allow for a longer backup time. I plan on adding a cooling fan along with an external current controlled power supply to charge the larger batteries. There are some ...
1
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0
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116
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Input filter for switching regulator
I'm trying to create an input filter for a switching regulator for automotive application.
My aim is to make a supply board, where from 24V come out 12V (from the buck) then 10V and 5V (from two LDOs)....
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0
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1
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159
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AP63203 Buck not working
Recently I have been experimenting with the AP63203, and I just have not been able to get it to output 3.3V successfully. Currently, the way I have been testing it is using an SMT to TH adapter, which ...
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2
votes
3
answers
194
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High voltage buck converter inductor voltage rating
We‘re designing a buck converter that should convert 600VDC down to 20V. For that purpose we use the ST VIPer26k.
We’re currently looking for an inductor (L2). The inductance is 1mH, but we‘re not ...
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0
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1
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173
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Output Stage Double LC Filter of a buck converter
I am trying to design a double LC output filter on a buck topology.
I want to set the bandwidth of my converter to be at 20 kHz. The swithing frequency would be equal to 250 kHz. The first resonnance ...
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2
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0
answers
78
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Phase shift at half the switching frequency of a dc-dc converter
I would like to know if, regardless of the control loop used (Voltage mode control, average current mode control, peak/valley current mode control), there is always a 90-degree phase drop at FSW/2 due ...
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3
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2
answers
310
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Sampling gain effect in buck converter
I recently learned that there is a phenomena called sampling gain effect in dc-dc converter and I am struggling to understand what this phenomena really is. Could someone enlighten me?
And I have seen ...
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0
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1
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117
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Circuit to convert 14.8v battery with max 4a discharge current into 12v, 9v and 5v output?
I am making a robot with multiple devices mounted on top. I am planning to buy either a 14.8v or 11.1v Li-ion battery which has internal BMS limiting maximum discharge current to 4A. Now I need 9v for ...
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1
vote
1
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159
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DC-DC current mode control frequency behavior
On a buck converter in average current control mode, for example, the inner current loop sees and manages the double pole created by the LC filter, and thanks to this the outer voltage loop is blind ...
- 341
2
votes
1
answer
146
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MPQ4470-AEC1 Layout guideline clarification
I am using MPQ4470-AEC1 in my design. In the datasheet page no 18 contains the layout guidelines.
I have some questions about guideline no:2 and no:3 .Those guidelines are given below.
Place input ...
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1
vote
1
answer
140
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Buck converter: PWM modulator input waveform
I have a question about the pwm modulator in a classical buck converter in voltage mode control (VMC). For the circuit in question, I copied over the picture provided in the answer of another SE ...
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1
vote
1
answer
221
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Buck converter inductor ripple current percentage
I am designing a buck converter using LMR36015 (Texas Instrument). The specifications are:
Input voltage: 24V (+/-10%) = 21.6-26.4V
Output voltage: 3.3V
Output current: 0.4A
Fsw = 1MHz
This leads to ...
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2
answers
2k
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Calculating inductor value for my buck converter [duplicate]
I'm trying to understand the SMPS operation.
The goal is to select inductor (L1) & capacitor (C1) values that satisfy the working condition below:
V1: 22-26 V range.
Power supply required: 1 A.
...
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1
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0
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46
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Are the prinicples the same for designing a high side vs low side buck?
I am an analog engineer that is getting into SMPS design.
This is a high side buck:
This is a low side buck:
simulate this circuit – Schematic created using CircuitLab
Assuming that I take ...
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0
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0
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75
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Problem with the current in a multiphase buck converter
I am a student of electrical and computer engineering and am currently working on a project that involves the study of a multiphase buck converter or synchronous buck converter (2 phases, in my case).
...
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1
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1
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38
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Why does this multi-phase buck controller have one phase to be driven by external driver?
https://www.renesas.com/in/en/document/dst/isl62883-isl62883b-datasheet
"The ISL62883 uses two integrated gate drivers and an external gate driver to provide a complete solution"
Why would ...
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0
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2
answers
165
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Buck-Converter input current spike
I want to make a PCB for DC-DC converter. I used TI’s Webench tool to create a buck converter design using the TPS5604 IC.
The input voltage is 13.5V and output voltage is 6V and maximum current is ...
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1
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0
answers
55
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Switching Voltage Regulator not Outputting Correct Voltage
I am working with a LM2576T-ADJ that is taking as an input voltage a 2 cell Li-Po battery that in my application won't decrease below 8V and should output a voltage of approximately 6V to power a pair ...
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0
answers
35
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PMIC MIC23451 operating voltage range
I am using Microchip SOM module in my project. Not using all the things in the SOM.
So we are redesigning the board with necessary components for my application.
Below is block diagram shows the main ...
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2
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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 ...
0
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1
answer
86
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Power stage of a buck converter as VCCS
In a buck converter using current-mode control as control loop, why can the power stage be seen as a voltage-controlled current source? Is it possible to understand that from a simple equation?
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1
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681
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Buck Converter Gain Margin and Phase Margin Review
I am using this IC (MPQ4470) for designing a buck converter (12 to 5 V - 3 A). Below is my circuit.
I am checking the stability of this circuit. My phase gain plot is given below.
My PM is 92 degree ...
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0
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0
answers
40
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Power dissipation of synchrononous buck converter cannot be reduced with gate drivers?
For this project, I had to want to reduce the power dissipation (< 2 mW) when the Rload is 54 Ω. These are the two circuits that I have employed.
When I sweep the pwm frequency vs Pdiss (power ...
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0
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1
answer
87
views
Buck Converter Output Is Coming To More Than The Designed Value After 3 Or 4 Months In Some Boards
I have a buck converter which converters 12V to 5V,3A. The output of this buck converter is going to a load switch and from the load switch it is going to a connector.
What we observed is that after 3 ...
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0
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1
answer
77
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MPQ4470 12V to 5V, 3A output is not simulating as expected in SIMPLIS
I am new to SIMPLIS, simulating this IC for converting 12 V to 5 V.
My first SIMPLIS circuit diagram is given below. My input is 12 V and the required output is 5 V. The load will take a maximum ...
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0
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1
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176
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Wider width or more fingers for CMOS transistor to reduce conduction loss in syncrhonous buck converter?
For a project, I am trying to optimize my buck converter to obtain a power efficiency of 87 %. The non-optimized buck converter gives a power efficiency of 86 %.
I try to size my PMOS 'power' ...
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2
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LTspice Frequency Response Analyzer (FRA)
This post is a continuation of this question.
LTspice recently introduced a new feature called frequency response analyzer, see the image below.
The green box shows the symbol for FRA. If you click ...
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126
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Buck converter inductor selection: maximum switch current limit vs output current
I need to select an inductor for this buck converter. Its output current is 3 A and maximum switch current limit is 6 A. As far as I know, I need to select an inductor whose current ratings (both DC ...
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2
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1k
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How to measure the stability of a buck converter using LTspice
Below is my buck converter circuit. How can I check its stability using LTspice?
I need to measure GM and PM.
Is this true that a 30–60 degrees phase margin and a gain margin of 2–10 dB are desirable ...
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5
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2
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659
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What are the advantages and disadvantages of feeding DC into an SMPS?
Can I feed DC into an SMPS to get a regulated output? If yes, why? and What are the advantages and disadvantages?
For example, I would like to input 200VDC to an SMPS with an input range of 100-230VAC....
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3
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3
answers
2k
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What do the waveforms in a buck converter look like just after turn on?
Below is the circuit diagram of buck converter.
I am studying about the buck converter. What I observed is everywhere it is explained with the help of waveform in steady state.
I have a couple of ...
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1
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106
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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 ...
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0
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1
answer
163
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Buck converter inductance vs Line and load regulation
I know how to design the inductor and capacitor for a buck converter.
My question is let the calculated value of the inductance be some "X".
May I know what will happen to line and load ...
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5
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1
answer
307
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Art of Electronics - buck converter ripple current derivation
I'm struggling to understand how this buck converter equation in The Art of Electronics can be true.
Page 642 shows this Buck Converter:
and then these graphs of current and voltage are also provided
...
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2
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1
answer
2k
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Input filter to reduce conducted emissions caused by DC/DC converter
This material from ROHM explains the input filter design for a DC/DC converter.
The filter circuit is given below.
I understood the design of Lf, Cf2, Cd and Rd.
If you see the 3rd page (design of ...
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