All Questions
70 questions
0
votes
1
answer
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 "...
- 119
0
votes
0
answers
63
views
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 ...
- 341
1
vote
1
answer
292
views
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: ...
- 119
0
votes
2
answers
190
views
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 ...
- 119
0
votes
1
answer
161
views
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 ...
- 1
2
votes
3
answers
194
views
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 ...
- 378
2
votes
0
answers
78
views
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 ...
- 341
3
votes
2
answers
310
views
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 ...
- 341
0
votes
1
answer
117
views
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 ...
- 45
1
vote
1
answer
159
views
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
1
vote
1
answer
143
views
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 ...
- 1,083
1
vote
0
answers
46
views
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 ...
- 88.8k
2
votes
1
answer
167
views
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
votes
0
answers
40
views
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 ...
- 113
5
votes
2
answers
659
views
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....
- 172
0
votes
1
answer
164
views
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 ...
- 3,061
2
votes
1
answer
2k
views
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 ...
- 3,061
6
votes
2
answers
1k
views
How does a buck converter's output ripple waveform become sinusoidal?
Below image is from Fundamentals of Power Electronics.
The ripple component of the inductor current will be flowing through the capacitor as shown in the ic(t) graph. This one I understood.
May I ...
- 3,061
0
votes
0
answers
59
views
High ripple in the output
We have chosen the MCP16311 buck converter for 4 V @ 1 A output.
design specifications as below.
Input voltage range: 5 to 20 V (source - USB type C mobile, charging adapter)
Output Voltage : 4 V
...
user220456
6
votes
3
answers
669
views
Why would you sense peak inductor current at the high-side PMOS transistor rather than at the NMOS?
I found this image for peak current mode sensing here.
Is there any reason that you sense the peak inductor current from the MP instead of theMN transistor? I know that ideally both should work but I ...
- 270
0
votes
2
answers
185
views
I would like to drop a variable DC voltage from input 30Vdc to 200Vdc to output 5Vdc with a max 200mA
I am new to electronics and would like some help if possible.
The incoming voltage will be variable from 30Vdc to 200Vdc coming from a bank of solar panels. The output is 5vdc at a max of 200mA. I ...
- 11
6
votes
3
answers
2k
views
Switch mode power supply vs DC-DC converter
I have started learning about DC-DC converters and switch mode power supplies (SMPS.) I know that the standard SMPS (attached fig. below) has an input rectifier, DC link capacitor, inverter, output ...
- 87
3
votes
2
answers
902
views
Frequency Response of Ideal and Real Type III Compensator
I'm trying to develop a Buck Converter with a Voltage-Mode Control, using a Type III Compensator, just like the one below.
So I calculated its transfer function, and then with the correct values of ...
0
votes
1
answer
189
views
How can I achieve a 25V - 5V @10A buck circuit, and a 25V - 8V @6.5A buck circuit? [closed]
I'm a computer engineer major in my senior year.
My team and I are making a SmartKart, and I'm responsible for power management and power designing.
Right now, based on several components we will be ...
- 1
5
votes
4
answers
2k
views
Why do buck converters end up in steady state?
I'm studying buck converters such as the one in the following simulation:
I have learned that for buck converters that are in continuous conduction mode and at steady state, the following equation ...
- 543
1
vote
0
answers
2k
views
Design of a Buck Converter with LC Input Filter
I am attempting to design a circuit from an exercise:
I am stuck at point (c). I attempted to calculate the voltage and current ripple in the LC filter using the small-ripple approximation, but this ...
- 119
2
votes
1
answer
288
views
Buck converter current
I have this synchronous buck converter.
Input voltage - 8.7V
Output voltage - 5V
Switching frequency - 350kHz to 450kHz
Output load current is 2A
Schematic:
I have an input capacitor of 68uF and an ...
user220456
0
votes
1
answer
451
views
When and how does a buck converter behave in a boost converter mode?
My question is with reference to this answer for this previous question.
The answer states that a buck converter will behave in a boost mode for some cycles during light load or no load condition.
Can ...
user220456
0
votes
0
answers
198
views
Glitches in inductor current waveform
I am using this DC-DC buck converter.
Schematics :
Buck converter specifications :
Input voltage - 18V to 32V
Switching frequency - 300kHz
Output voltage 9V
Load current - 0mA to 200mA maximum.
...
user220456
0
votes
3
answers
915
views
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
1
vote
2
answers
1k
views
DC-DC buck converter low input voltage behavior
I am using this DC-DC buck converter.
Schematics :
Buck Converter Specifications :
Input Voltage - 18V to 32V
Switching Frequency - 300kHz
Output Voltage 9V
Load Current - 0mA to 200mA Maximum.
I ...
user220456
0
votes
1
answer
99
views
Control Circuitry in the Buck Converter Design
In this question, the last line of the accepted answer states that - That's why the text suggests using 1/5 or 1/10 of the switching frequency as an upper limit in terms of how fast you should design ...
user220456
6
votes
1
answer
3k
views
Slope compensation in current mode control
There is something a little bit confusing to me between papers dealing with the theory of external slope compensation in current mode control of SMPS and application notes dealing with implementation (...
- 1,078
1
vote
0
answers
66
views
Current mode buck modeling
I am following this document Loop response consideration in PCM. Here I am implementing fig 5 schematic in page 9. From equation 1 to 22 got me some of the hidden values of the schematic which I have ...
- 305
0
votes
1
answer
321
views
SIMtrix/Simplis Simulator
I'd like to use SIMtrix/Simplis Simulator for simulation of SMPS design, and I'm about to start building a peak current mode buck converter like the one shown below from richtek.com:
but ...
- 1,078
0
votes
0
answers
226
views
TPS54260 DC-DC Buck Regulator BOOT and PH pin voltage drop
I am using TPS54260 Buck converter which steps down 16V to 5V output.
Load current is 600mA max.
To the inrush current through the output inductor, I did some rework. But after some rework, my 5V ...
user220456
0
votes
1
answer
937
views
Relationship between switching frequency and controller's crossover frequency in DC-DC converters
I am reading some answers related to my questions based on control loop stability of SMPS.
I came across this question.
The accepted answer states:
A switch mode power supply is essentially a ...
user220456
1
vote
1
answer
755
views
Bad Waveform on Output of Buck Converter
I have designed a buck converter (poorly) and have been getting terrible noise. I made a post here where I was given suggestions on how to do a proper layout for my buck converter. This post also ...
- 381
1
vote
1
answer
84
views
Current Sensing Design
while using MCP1630 in switch mode power supply design, in the datasheet they gave the input bias current of the "current sense pin"
what are the considerations the designer should take while ...
- 1,078
0
votes
0
answers
136
views
Output Current Derating for Buck converter for powering RF sampling data converters
I am new to the use of DC-DC converters.
I am designing power supply for powering DAC from TI whose part number is DAC38RF80.
DAC38RF80 is high speed RF sampling DAC with sampling rate as high as 9 ...
- 41
0
votes
1
answer
465
views
What does the ripple frequency of a buck converter indicate and how does it affect the DC device connected to its output?
What is the desired ripple frequency for buck converters connected to computers, networking device as power supplies?
Can we judge the quality of power supply from ripple frequency? (buck converter ...
- 137
0
votes
1
answer
455
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 ...
- 311
0
votes
2
answers
1k
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?
...
- 1,008
1
vote
1
answer
146
views
LTC1775 Buck converter component question
I am trying to design a 12v,10A buck converter using a with LTC1775 and have gone through the calculations assuming a 40% inductor ripple current and a switching frequency of 150kHz. This gave an ...
- 15
1
vote
1
answer
591
views
DC/DC step-down regulator destruction because of inductive load?
I was evaluating PAM2316 DC/DC step-down converter and destroyed several of them, I suppose the cause could be an inductive load.
See my schematic and my layout here:
Let me explain: The circuit was ...
- 292
0
votes
2
answers
481
views
Synchronous Buck High Side Driver - Why is the Fall Time of High-Side Gate Drive so Slow?
Below is the picture of my gate drive signals. The blue trace is the low side gate signal and the yellow trace is the high side gate signal. Both signals are measured across the gate and source of the ...
- 121
0
votes
2
answers
174
views
12V in, 1V @ 12 Amp Out, Buck, Why 100 Amp MOSFETS and 60A Inductor?
I was showing someone the TI Workbench and it came up with this schematic.
94% Efficiency, switching Freq. 100khz
With voltage of 12v and 1v, max Amps of 12, why would it select 25v and 30v 100 Amp ...
- 7,517
-1
votes
2
answers
7k
views
UC3843 buck converter
I want to build an adjustable buck converter with uc3843 ic.
I built up a circuit in LTSpice for simulating.
The problem is that, i want to adjust the output from 3v to near input voltage.
With the ...
- 1
0
votes
2
answers
379
views
MP2359 dies after reset
I'm using MP2359 for converting 12V from 20V.
Datasheet: http://www.monolithicpower.com/desktopmodules/documentmanage/api/document/getdocument?id=269
I'm using the recommended sch and layout designs ...
- 1,043
0
votes
1
answer
583
views
Approximation when deriving buck closed loop transfer function
Can anyone explain why \$\frac{\Delta V_x}{\Delta D} = V_{in}\$ here? It seems to me that they are assuming that \$V_x = V_o\$ ( this is only correct for average voltage). However, if they use the ...
- 1,661