Questions tagged [sepic]

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11
votes
2answers
2k views

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 ...
9
votes
6answers
11k views

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?
8
votes
4answers
2k views

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 ...
5
votes
4answers
5k views

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
4
votes
3answers
2k views

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{...
4
votes
1answer
284 views

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 ...
4
votes
1answer
90 views

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, ...
3
votes
2answers
564 views

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... ...
3
votes
1answer
808 views

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 ...
2
votes
2answers
4k views

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 ...
2
votes
1answer
194 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, ...
2
votes
1answer
134 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 ...
2
votes
1answer
539 views

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_{...
2
votes
0answers
141 views

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. ...
1
vote
2answers
1k views

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 ...
1
vote
1answer
824 views

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 ...
1
vote
0answers
140 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
0answers
141 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 ...
1
vote
0answers
1k views

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
0answers
387 views

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 ...
0
votes
1answer
278 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 ...
0
votes
1answer
130 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 ...
0
votes
1answer
151 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 ...
0
votes
1answer
1k views

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 ...
0
votes
2answers
576 views

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, ...
0
votes
2answers
135 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 ...
0
votes
1answer
60 views

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
0answers
54 views

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
0answers
59 views

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 . ...
0
votes
0answers
55 views

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 ...
0
votes
1answer
253 views

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 ...