Questions tagged [buck-boost]

A non-isolated DC-DC converter topology

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102 views

I have a 5 volt converter but I also need 3.3 volts, what should I do?

Goal is to get 5V and 3.3 V output by the use of a buck/boost converter. Important is to use a converter instead of an LDO for heat reasons. I want to draw minimum above 0.8A, preferably 1-1.2A at the ...
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18 views

The right way to control EN pin of TPS63806 using STM32 MCU

I have a 3.3v STM32L4 MCU powered by it's own supply and an external circuit powered by a buck-boost TPS63806. The power source is a 18650 battery, providing from 2.8-4.2 volts. I want to turn on and ...
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41 views

Two TPS5430 inverting buck-boost converter modules failed in a row, am I using them wrong?

I've bought three of these inverting (negative voltage) DC-DC converters. I'll include hi-res images of the module's PCB at the end of my question. Two of the three failed in a row during initial ...
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37 views

Working of -12V buck-boost supply using LM2576

I want to make a -12V supply and I came across a circuit using LM2576 that match my requirement but I am not confident enough about its working. There is a note in the datasheet page no-16, ...
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40 views

Buck boost converter inductor rating

I am designing a buck boost converter with a 12v output, and 50A current output. The input range is 8v-14v from a supercapacitor. However based on the Texas Instrument buck boost design sheet Basic ...
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40 views

on/off pin problems with the LM2678 5.0

PCB: My name is Ertuğrul. I made a regulation board with an LM2678 but I have a problem: I provide 12V input but I can not get 5V output. I only get 5V with the on/off pin enabled, but the datasheet ...
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1answer
50 views

How can I step up 6.5V to 10V?

I'm working with a buck/boost LED driver that uses a 0->10V dimmer input. I would like to use the output of an open-source LED module as a switch for the LED driver. The LED module outputs 0 V in ...
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1answer
25 views

Inverting Buck-Boost -12V converter Schematics

I saw two schematics for inverter switching converters for -12V output. I wonder, the first schematic uses many components compared to the second one but still, the output current rating of 2nd one is ...
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1answer
51 views

Is there a mathematical representation that represents the output voltage of a buck or boost converter in discontinuous mode?

Recently I have learned that in buck or boost converters, the output voltage depends only on the duty cycle and input voltage in continuous conduction mode or when current is continuous. However, in ...
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59 views

How does a boost converter allow for a gain in output voltage by just switching the positions of the inductor and switch?

I get that in a buck converter, a low pass LC circuit was attached and this effectively filters out high frequencies. If the bandwidth is configured so that it is lower than the switching frequency, a ...
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43 views

Generally, how do you describe the functions of the basic parts in a buck or boost converter? The parts are enumerated in the post [closed]

Here is a homework question I am answering. 1. Explain the function of the following parts in the DC-to-DC converter. a. MOSFET b. Schottky Diode c. Inductor d. Capacitor Here is an accurate basic ...
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19 views

How does changing the inductance, capacitance and load in a buck or boost converter affect the circuit?

Before anyone calls me out, yes I am asking electronics related questions due to homework but honestly I am able to answer some of them. There are just some that I need StackExchange insights. For ...
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2answers
69 views

Why specifically use a MOSFET and Schottky diode on a buck or boost converter and not other transistors or diodes?

My electronics professor is currently teaching DC-to-DC converters. He decided to drop us some theoretical homework and just postpone the experiment. He gave us some questions. This is one of those ...
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37 views

Not able to figure out how to solve this as \$I(s)\$ is used in the feedback

I am not able to figure out the approach to this problem because \$I(s)\$ is connected to feedback instead of \$V(s)\$
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1answer
57 views

Bidirectional buck boost converter [closed]

I am searching for a bidirectional buck boost converter evaluation board for charging and discharging the batteries. Input= upto 30V DC Output= upto 10V to 20V DC Current= less than 10A I always ...
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1answer
41 views

How to take a nixie power supply and make a low power frequency modulated signal

The project I am working on requires a low input voltage stepped up to a high voltage at a certain frequency and PWM with low power. I found a nixie power supply circuit that can supply 170V at 20mA ...
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39 views

Buck-boost with LT8705

I would like to do a buck-boost using H-bridge topology. I found the LT8705. I have two questions I don't understand. How to choose the inductor of H-bridge buck-boost? The datasheet is using boost ...
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1answer
57 views

simple DCDC Step Up converter mystery

I'm designing a self sustaining guitar that has 6 amplifiers onboard and runs on a li-ion pack. Power draw is a about 2.5A when on "full power" and I decided to make my own step up converter ...
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1answer
55 views

Buck-Boost polarity

One of the disadvantages of a Buck-boost converter is the minus sign at the output (Transfer function of Vo/Vin = -D/(1-D) ) My question - Why can't we just place the load rotated? Wouldn't it solve ...
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1answer
38 views

DC-DC Boost Converter \w Inrush Current Protection - Voltage

I wanted to dive in Power Electronics and create a 24V DC-DC Boost Converter that would run from 2.5 to 5 V power supply. 80% efficiency was assumed, and 30 kHz frequency chosen for the PWM. Initial ...
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1answer
72 views

Why overshoot happens in Inductor voltage in an open loop DC-DC buck converter?

I am extremely confused about why this overshoot occurs in the Inductor voltage waveform in buck converter and also why the time to achieve steady state reduces on increasing the load resistance. ...
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33 views

LTspice MOSFET stops charging capacitor past Vt

I'm building a buck-boost converter that transfers C1's charge to C2. In the schematic shown below, C1's initial charge is 4V. When I use switches instead of MOSFETs in the circuit, everything works ...
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1answer
96 views

3.7 to 5 V boost converter does not work as desired

I was trying to boost 3.7 V to 5 V @ max 1A. Used LTC3426 DC-DC converter for it. LTC3426 datasheet here. I made a simulation before printing PCB and I get the voltage I needed. However, now I have ...
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30 views

How is a zeta converter different from a buck-boost converter?

Both the topologies have the same output equation, but zeta appears to be better. Why's that?
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40 views

Buck converter with current and voltage regulators

I need to find scheme for Buck converter with adjustable output voltage from 0 up to 12V. Also it may have an adjustable current limit. Max current output is 10A or at least 5A. Actually I will need ...
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1answer
52 views

How I can manage my voltage and current requirement for my loads

I have a battery power source of rated 25.9 V, rated capacity is 10Ah I want pure 24VDC and enough current for the following loads 3 motors each of the operating voltage is 24V and nominal current is ...
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1answer
68 views

LTspice voltage source with varying Ton / Tperiod

I'm trying to simulate a buck-boost converter where Vin and Vout are constantly changing. As a result, the time it takes to charge/discharge the inductor varies as well, and a voltage source that ...
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69 views

Getting negative pulse on Q2 mosfet at gate to source pin

BOOST CIRCUIT: Working on DC-DC boost converter circuit as given bellow. Getting negative pulse of -25.6V on Q2 mosfet at gate to source pin. This is much higher then then its maximum operating ...
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1answer
35 views

Increase runtime: batteries in parallel -> buck || batteries in series -> boost

I have 18650 batteries, I created 4S packs with 6P in each. I have a 12 V 2 A solar panel and I want to use this panel to charge them ( i know I need a charge controller and I must balance charge them ...
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51 views

LiPo battery sparks when used with DC step up convertor

I'm using a LiPo battery 700mAh 3.7V with MT3608 DC-DC step up boost converter module 2V-24V 2A. The problem is when I connect these to anything or even the wires just touch each other they produce a ...
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1answer
36 views

Electronic Power Selecting Switch

I have a circuit which works with a battery normally. The nominal voltage of battery is 3.7 V and I am using boost converter to make it 5 V. And I have a charging circuit of this battery too. So, my ...
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1answer
90 views

3.7- 5v boost converter issue

I am trying to do boost converter with using mc34063 ic for my project. When I simulate the circuit on LTSpice with 3.7V input. I can get 5V output without any problem. However, when I change the ...
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1answer
56 views

Connecting buck converter to 10mF 40v filter capacitor

I have a very well made custom-made lab supply given to me by a friend. It is capable of 1.6A max and 32V DC voltage. I want to ...
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43 views

Switch regulator driven by a super capacitor

I am trying to design a Power Management circuit with some quite tricky (for me at least) requirements. Basically I have a quite high 30-40V (varies) input voltage, with a very low current limit (6mA ...
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2answers
80 views

DC Step-up Boost Voltage regulator (High Ampere)

I’m working on a project, where I want to go from 5 Lithium-ion cells in series, to 5 Lithium-ion cells in parallel, for versatility purposes i.e. in time, I want to be able to change the output ...
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1answer
60 views

Boost converter voltage drop when connected to load

I have designed a boost converter based around the TPS61200 chip. This is a low voltage boost converter with a varying input of around 1.5V and 400mA. The output of the circuit is 3.3V. However, when ...
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2answers
79 views

5V/2A Fixed Output Buck Boost Converter Design

I am trying to build a fixed 5V buck boost converter with input voltages ranging from 3-7.2V (which is from a battery) and maximum output current with 2-5 A. My use case for this converter is to power ...
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41 views

Variable power supply using xl4015 module

I am planning to make a variable bench power supply using a 12 0 12 5 amp step down transformer. While using full wave rectifier br1010 to rectify and capacitor to filter, I get 42 v at no load. I was ...
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1answer
66 views

Which transition mode for the four switch buck boost converter is correct?

I am currently researching on the application of the Four Switch Buck Boost Converter on a Fuel Cell Hybrid Vehicle, and I would like to ask about the transition mode of the buck boost converter. I ...
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55 views

12v load doesn't turn on with boost converter

I'm trying to build a power source for my router during load shedding. But the router doesn't turns on while connected to any sort of boost converter. I have tried 5 more different routers from ...
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81 views

Under voltage lockout circuit design

I need to be able to switch a load circuit off when the output voltage from a buck boost converter is around 3V (or below 4V or 5V). The converter is powered by a 10W solar panel and the load can draw ...
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1answer
76 views

DIY Power Bank For Router & Fiber ONU

I'm trying to build uninterrupted power bank for my 9V 1A router and 12V 0.9A ONU. I have made a circuit Mindmap. But I think I have done some questionable things in it. Such as, I don't know the ...
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2answers
100 views

How to control the non-isolated bidirectional buck-boost converter?

I have been working on a control software for below given bidirectional buck-boost converter. The planned usage is for charging and discharging of a traction battery in electrical vehicle. I am not ...
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0answers
66 views

Mosfet drive for inverting buck boost converter

I'm working on an inverting buck boost circuit for university and have come up with the following schematic. I'm ordering quite expensive parts so I wanted to get some opinions and advice as to ...
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2answers
131 views

Where does the negative inductor current go during CCM at no load in synchronous converters?

As you all know, there are two primary mode of operation for dc-dc converters : CCM and DCM. At no load, the inductor current stops at zero at DCM. However, if CCM is enforced (such as Forced PWM), ...
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175 views

Inductors and caps on buck-boost converter getting very hot under medium-ish load

I'm currently using a buck-boost converter (generic XL6009 buck-boost like this one) to power a router and fiber terminal from a 12V battery backup system. The reason for using the buck-boost ...
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52 views

Boosting 3.0 - 4.6 Volts to 5V

I found this circuit that will auto switch between power between USB (5V) or a LiPo Battery (3.0V - 4.2V range). The schottky diode, D4, can have a voltage drop of about 0.4V which is too high for me....
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110 views

Buck-Boost Converter Modeling

I wanted to perform AC analysis for a buck boost converter using SIMetrix/SIMPLIS for simulation, using this simulator the designer does not need to the average model to get the frequency response of ...
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2answers
68 views

Boost Voltage from 5V to 19.1 V

Long story short, I have a Toshiba laptop. Its adapter outputs 19.05 volt and 3A. I wanted to build a powerbank for my laptop. I have built one using Li-ion cells. 5 cells in series with each cell as ...
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1answer
153 views

Difference between placing unidirectional TVS diode before fuse or after P mosfet

In the buck-boost converter I am finishing, I came out with this question. At Vin (12V in my circuit) I place a 7A fuse and a P mosfet (IRF5305) to prevent reverse polarity issues. Because I want to ...