Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [buck]

A non-isolated DC-DC converter topology which outputs a voltage less than or equal to the input voltage.

A buck converter is a non-isolated DC-DC converter topology used to step down voltage. It is one of the most fundamental converter topologies in existence.

The basic buck converter power train is comprised of a switch (usually a MOSFET or transistor), an inductor, a diode, and a capacitor.

Public-domain buck converter image from Wikipedia

The duty cycle of the switch determines the ratio of load voltage to supply voltage:

$$ \frac{V_{out}}{V_{in}} \mbox = D $$

An improvement on the buck converter is the synchronous buck converter, where the diode is replaced with another switch. This increases the efficiency of the converter but requires more complicated control.

Wikipedia: Buck converter

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Is discontinuous conduction mode of a buck converter more efficient than continuous conduction mode?

Can someone explain why you need less duty cycle % to achieve the same output voltage in the discontinuous mode of operation in a buck converter? This indicates to me that it's more efficient. If the current in the inductor goes to 0, then the…
AQUAMAN
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LC Low Pass FIlter in Buck Converter

Hi In this circuit below: What role is the LC Low Pass filter playing? The switch is switching ON-OFF alternatively, at a frequency which determines the Duty cycle, and we get an average output at the point before L. Now why do we need to hook up…
Sherby
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Buck Converter - Coss Loss

From: https://fscdn.rohm.com/en/products/databook/applinote/ic/power/switching_regulator/buck_converter_efficiency_app-e.pdf Can someone explain why the high-side MOSFET causes a loss due to its C_OSS. The charge from the C_OSS flows to the load,…
muosac
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Buck converter quiescent current is too high

My circuit uses a LMR50410Y3FQDBVRQ1 buck converter to convert an input voltage from a LiPo battery to a 3.3 V supply voltage. The first batch of the PCB uses the 3.3 V fixed output variant (LMR50410Y3FQDBVRQ1), so I don´t assemble R203 and R204.…
Kampi
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Chaining buck converters

I am using these step-down adjustable buck regulators for various purposes (hobby projects and experiments) and they work more or less fine. But I have this little concern - when they convert relatively high voltage (~20V) to relatively low (5V or…
Mishony
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Effect of using buck converters in parallel

What is the effect, downside or purpose, if any, of using buck converters in parallel? For example, to connect the Vout and Gnd together on two converters. Could this be used to increase the current capability? Assume that the converters are…
Pål Thingbø
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Using an NMOS for a high-side switch in a buck converter

I know that to use an NMOS as a high side, you need a gate boosting circuit! I am just here to check my understanding on what WOULD happen if I did use an NMOS device without a boosting circuit and how exactly the transient turn on behaviour would…
alayoiskgfbfqhxjiw
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Buck Converter MC34063AP

I'm very new to electronics, this is the most complicated circuit I've tried to create thus far. I'm attempting to step down a 24V DC input to 5V output. I'm skipping the output filter for right now just until I get the buck to work. I know that in…
Sean
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I assume that AOZ1280 buck converter misses datasheet specs

I have tried setting up this cheap AOZ1280 buck converter to give output of 3.3V from input of 3.5V to 4.2V without success. Please check my schematics below. What happens is that I can not achieve an output of 3.3V unless the input voltage is at…
davaradijator
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Buck converters- No Load condition

How exactly do buck converters work under no load condition? The capacitor voltage will try to charge up to the peak input voltage, with no load connected across it to discharge. How to avoid this problem? ** I've included the simulation result.…
JGalt
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Resonant Frequency of LC Circuit in Switching Converter

Why do we set resonant frequency of LC circuit in a buck converter to be less than 10% of Fsw? For example, if Fsw is 300 kHz, why should resonant frequency be around 30KHZ. I am guessing it is due to voltage spikes at resonance, but can't it be…
Sherby
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Any qualitative analysis saying RC snubber required or not for High current Buck converters

I have a design where i am using TPS53355 from TI to generate 0.9V @ 15A from 12V(10V-14V). For this design, i want to know whether RC Snubber required or not? as far as i know, Generally in High current converters inductor will store lot of energy…
user19579
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Role of Capacitor when switch is open in Buck Converter?

in a buck converter, initially, when switch is closed, then capacitor charges and stores energy. But when the switch is opened, then Inductor current flows through thr free wheeling diode, but what happens to the charge stored in the capacitor?
Sherby
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Why is transient performance of voltage mode buck affected by bandwidth?

For voltage-mode controlled buck converters, we often hear that they have poor transient performance under load steps as the bandwidth is usually limited. I don't understand this. Bandwidth as I recall was for the small-signal performance (over…
AlfroJang80
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EMC (radiated emission test) issue in buck converter

i am designing CV smps 12V 1A (with EMC design) post that output side i will use dc to dc buck (Vin-12V Vout-9V, 400mA) or Boost convreter (Vin- 12V VOut-36v, 100mA). which configuration will be more suitable considering don't need to add EMC…
Tanvir Fakir
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