Questions tagged [sepic]
For questions about single-ended primary-inductor converters (SEPICs), which are a type of DC/DC converter. Use with the "dc-dc-converter" tag.
45
questions
11
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6
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What do phase dots on an inductor mean?
I have a SEPIC supply with coupled inductors. The inductors have phase dots. What do these "phase dots" mean? Is it important to have the phase dot in the same place?
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11
votes
2
answers
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How do I size the coupling capacitance for a SEPIC converter?
The app notes I've seen for a SEPIC converter1 all tell me to size the coupling capacitor for ripple currents and voltages. I haven't seen one that tells me how to size the capacitance. Obviously ...
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votes
4
answers
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Can I use a common mode choke as a coupled inductor in a SEPIC converter
I do not really understand the difference between common mode chokes and coupled inductors. They are both 2 coils wrap around the same core but I know they have different purposes.
I want to design a ...
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6
votes
1
answer
387
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Vin: 2-36, Vout: 4.2. Should I use step-up, followed by step-down, or SEPIC?
My application has a small device, which draws about a watt, and is powered through a small dynamo, backed by a battery:
The dynamo generates 33 volts at maximum speed, close to L6902's max input ...
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5
votes
3
answers
3k
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Isolated DC/DC flyback/SEPIC
As far as I understand the flyback topology, it can be used in both buck and boost converters.
What I am not sure about is: Does it also work for the case where buck-boost is needed, i.e. \$V_{\text{...
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5
votes
4
answers
6k
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Coupled inductor vs an actual transformer?
What is the difference between a coupled inductor and an actual transformer? The LT3757 datasheet mentions that I need a coupled inductor for the SEPIC to work
- 31k
4
votes
1
answer
241
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Is there a problem using electrolytic (polarized) capacitor as coupling capacitor in SEPIC converter?
I found this circuit from here and have been thinking about to build it:
The author present it as Ćuk converter but I understand it as SEPIC, after reading this and this.
Q: My main concern is, ...
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3
votes
4
answers
132
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13-48 V SEPIC - > 19.5 Vout; 0.5 A
I am trying to design a SEPIC converter with the parameters stated above and have already drawn a schematic using the LM5022 IC. I have built the system and noticed a few things:
The output voltage ...
3
votes
2
answers
7k
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SEPIC vs Cuk vs Zeta Converter
My understanding is that SEPICs, Cuks, and Zeta converters all provide a stable output voltage despite an input voltage that can vary either above or below what is desired. The SEPIC and Zeta ...
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3
votes
2
answers
570
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12V @ 1A from a 6V to 20V input
I have a 6V to 20V input I want to convert to 12V at 1 amp maximum continuous current. The output must be the same polarity as the input, so that pretty much means a SEPIC is the only way to go... ...
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3
votes
2
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Switching supply burning mosfets, what is happening?
I have been working on a SEPIC converter for an electronic cigarette power supply. This application involves using two 3.7v INR batteries in parallel, rated for an appropriately high current ...
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3
votes
1
answer
871
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SEPIC converter capicitors calculation
I have got a SEPIC converter design see here:
http://www.linear.com/docs/27994
The calculation of the SEPIC converter starts at page 21.
For the input capacitance on page 17 they tell you need:
\$I_{...
- 111
2
votes
1
answer
232
views
Sepic based charger
I have acquired a LT1512 Sepic based controller which is a controller for charging purposes.
I have followed the datasheet as much as can, read few articles on how to set it up for my purposes, ...
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2
votes
1
answer
171
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Ceramic output capacitor selection for ripple current (SEPIC)
I'm designing a SEPIC converter based on a wide input voltage range SMPS controller (LTC3758). The requirement is for a wide input voltage (10-60V) with a fixed output of 28V @ 1.5A. I'm trying to ...
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2
votes
1
answer
186
views
Lossless Resistor model in PSpice?
Is it possible to make a lossless resistor model in spice? I want to test the large signal model of my DCM SEPIC converter (without linearizing it). OrCad's PSpice library doesn't seem to have it, but ...
- 23
2
votes
0
answers
171
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Why does my SEPIC converter output more power at higher temperatures? What are the implications of this behavior?
I have a Pololu S18V20ALV SEPIC voltage regulator board that is wired to a high-amperage 5V USB power source on the input and a DC brushless fan on the output. The output is set to about 5.5V. ...
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1
vote
1
answer
82
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Beginner seeking feedback on circuit design: SEPIC with adjustable voltage
I recently got very interested in electrical engineering. After watching a bunch of YouTube videos on circuit and PCB design, I figured it's finally the time to get a bit hands on. I decided to start ...
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1
vote
2
answers
71
views
Calculating ripple voltage across sense resistor (SEPIC DC-DC Converter)
I am designing a SEPIC DC-DC converter based on the LT3758 (Analog Devices). In the data sheet the maximum switch ripple current percentage is calculated using the ripple voltage across the sense ...
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1
vote
1
answer
355
views
SEPIC vs. ZETA feedback
When I was reading through the RECOM book of knowledge DC-DC, I found out that the SEPIC converter has more chance of having resonance feedback than the ZETA converter. They mention that the SEPIC has ...
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1
vote
2
answers
1k
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Troubleshooting a SEPIC regulator (MIC2296)
I am trying to regulate a 5V input, which drops to around 3.5V when a large load is applied. I need to keep the 5V steady, and I am willing to do this at the expense of current, which is why I thought ...
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1
vote
1
answer
2k
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Compensation Capacitor and Resistor Values
I'm currently working on a Power Electronics project which I will convert 10-28V input DC voltage to 12V DC output voltage. I've deciced to use LM3481/3488 configured as SEPIC in my project. I've ...
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1
vote
2
answers
1k
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Low voltage DC UPS - confirm specs
I've looked at the other answers here regarding building a low voltage UPS and have come up with the following design.
Requirements: 1) At least a couple of hours of up time; 2) USB power 5V @500mA, ...
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1
vote
1
answer
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LTSpice SEPIC simulation current spikes
I am designing a SEPIC power supply using the LT3758. I have simulated the circuit in LTSpice and all the waveforms are as expected except the L1 current.
Here I see massive overshoots when the MOSFET ...
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1
vote
0
answers
171
views
Confusion of the working principle of Isolated SEPIC converter
I am a bit confused about the current flowing in the magnetizing inductance L_m when the switch is off.
I am reading a book(Erickson & Maksimovic, Fundamentals of Power Electronics, 2020), ...
1
vote
0
answers
32
views
Secondry side pulse by pulse current limit
Coupled inductor SEPIC converter using UC3843.
Vin nominal = 14 V
Vout max = 30 V
Iout max = 2 A
According calculations based on many resources the MOSFET's current will be
Peak = 7.62 A
RMS = 5.3 ...
- 31
1
vote
0
answers
184
views
How to limit starting current of a SEPIC based LED driver?
I have designed a SEPIC based LED driver which gives 60 V, 350 mA constant output with a good power factor. It is connected with 220 V AC source.Then I have used full-wave rectifier.After ...
1
vote
0
answers
153
views
SEPIC converter working in BURST mode without having one
I designed a SEPIC using the LT3467 with coupled inductors. It supply 17V starting from a 12V input.
On the simulator (LTSPICE) everything works, but on the test board there is a problem.
With 70mA ...
- 19
1
vote
0
answers
2k
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DC/DC Converter MOSFET switching
I am currently building a SEPIC converter. The signal arriving from the MOSFET driver to the MOSFET seems all good, however the Vds doesn't seem to follow the drivers signal and it makes the MOSFET ...
1
vote
0
answers
439
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SEPIC converter current waveform question
I am designing a SEPIC converter, powered by 3.7 V Li-Ion cell. Frequency 500kHz, Transformer 10uH per side, 1:1 ratio. Ferrite material #87. Output to be variable by adjusting duty cycle.
It has ...
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0
votes
1
answer
99
views
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 ...
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0
votes
1
answer
59
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Coupled Inductor for DC-DC Converter ~50W
I'm designing a DC-DC Flyback or SEPIC converter, not decided yet.
The converter is used to source some power LED's.
The output voltage up to 60V and 1A with an input of 12-24V.
The switching ...
0
votes
1
answer
652
views
LTspice XVII problem simulating SEPIC converter
This is the second time I'm trying to simulate a SEPIC converter today. First I went with LT3959, but after hours of trying to make it work, I assumed there is something wrong with the component and ...
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0
votes
1
answer
63
views
Meaning of these inductor dot symbols
For the following circuit from the NCV5171 datasheet:
What is the meaning of a solid dot on one inductor and an open dot on the other?
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votes
1
answer
200
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Why does this SEPIC buck-boost oscillate so much?
I've made this SEPIC regulator based on this design, using a MT3608 boost regulator, which has the same oscillation (ripple) as this question:
I've made these changes:
C1=100uF, C2=470uF
R2(bottom ...
- 1,042
0
votes
1
answer
192
views
TI LM3488 SEPIC, adjustable power supply down to 0 volts
I decided to make an adjustable power supply with input voltages from 3 to 6 volts (4A), and output voltages from 2 to 12 volts. But I had a thought, that as long as I'm making it, I should make it go ...
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0
votes
2
answers
147
views
How to choose V_out resistors for LT8494 SEPIC
I am in the middle of a project where i want to use a mcu (ST32F3028U6 with DAC of 2.4V - 3.6V) to control the V_out voltage of a LT8494 SEPIC DC/DC Converter. I understand the basic operation of the ...
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0
votes
1
answer
22
views
How to calculate components values for LM3421 in SEPIC mode
How can I calculate the components values for LM3421 in SEPIC mode?
In the LM3421 datasheet, there is not much information about SEPIC topology. (Section 9.2.9.2 is labelled "Detailed Design ...
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0
votes
0
answers
86
views
Powering a 12 V Relay and a 3.3 V Microcontroller with one Power Supply
I'm trying to power the LN298 motor driver in order to use a 12V linear actuator. This motor driver comes with a 5V voltage regulator, so you can power a microcontroller with one power supply. The ...
0
votes
0
answers
90
views
Buck converter after SEPIC converter
I have designed a SEPIC and Buck converter using the TI power designer tool, which I have individually tested, and proved to be working correctly. They are both of the non-isolated type, but when I ...
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0
votes
1
answer
60
views
SEPIC converter : why average secondary inductor is the output current?
I can't get the reason the why the average secondary inductor current is the output current.
Simulation confirms it's true, as well as documentation.
But I haven't found any clear explanation. Sorry ...
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0
votes
1
answer
170
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Selecting capacitor for SEPIC converter
I'm looking for an advice how to select capacitors for my SEPIC converter. I have done calculations, but I haven't find Cin, Cs and Cout yet. What seems like a problem is that there are few work ...
0
votes
0
answers
107
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sepic converter using lm3478
Is it possible to make a sepic converter of 120 W using LM3478 ?
I am trying to make the circuit in TI web bench but it is not supporting over 12V 3A in LM3478.
0
votes
0
answers
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building real simulation in multisim(NI company) of dc-dc SEPIC convertor
hi I am trying to build real simulationin multisim of dc-dc SEPIC convertor how ever in my output voltage i get a lot of RIPPLE . the problem is that I get a lot of spikes in my capacitor current . ...
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0
votes
0
answers
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High voltage drop over output diode sepic converter
I made a SEPIC converter please see the wiki for the scematic:
https://en.wikipedia.org/wiki/Single-ended_primary-inductor_converter
Observation:
The output is 12V 2A max. When I use a scope I see ...
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0
votes
1
answer
277
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PWM Dimming results in input ripple due to excessive inrush current
I use a constant current SEPIC boost regulator ([TI LM3410X) to run a 8.5V 400mA OLED panel from a single Cell Lithium polymer battery. I have noticed that the input voltage ripple is too much (~1V ...
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