Questions tagged [buck]

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

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1 answer
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Circuit to invert logic of enable pin on IC

I have an LM2596 DC-DC buck converter which has an enable pin that enables the IC when the voltage on it is lower than 1.4 V and disables it once voltage goes above 1.4 V. Is it possible to create a ...
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4 votes
2 answers
455 views

Why is my DC-DC buck converter consuming 8mA of current with no load connected?

I am using a TPS5430 buck converter on my PCB which is converting 12V to 8V. If I shutdown the buck converter using the enable pin it consumes only a few micro amps but if I leave it enabled with no ...
0 votes
0 answers
31 views

Series capacitor buck converter small signal model

Does anyone know how to do the small signal model of the series capacitor buck converter? I can't find a related paper talking about this one. I think the small signal model is not the same as the ...
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2 votes
0 answers
63 views

How to increase the damping of a buck system?

I have designed a buck circuit. The Bode plot of my system is as follows: I use a type Ⅲ compensator to control my system. The switching frequency is 100 kHz. The cut-off frequency is 20 kHz and the ...
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4 votes
1 answer
186 views

Questions regarding this power module

I'm looking at this power IC module. I assume it's a buck converter. In that case, on page 16 of the datasheet, Equation 4.1, there's this formula: Rvout = 8.2 kΩ * TRIM. If TRIM is 5, then what would ...
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2 votes
1 answer
47 views

What is the function of the feedforward capacitor on the LM2596-ADJ?

I'm looking at the LM2596S datasheet and notice that on page 7 (figure 3) it recommends a "feedforward" capacitor for the adjustable variant. The example schematic on page 9 shows a ...
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2 votes
5 answers
130 views

I calculated the power loss of a switching regulator and it doesn't match the datasheet. Am I missing something?

I'm trying to figure out how On Semi's LM2575D2T-5G is only 77% efficient. It's the fixed 5 V output version of the component. The datasheet gives Vin = 12 V and Iload = 1 A. Based on this, power in = ...
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1 answer
38 views

Powering ESP32S Node MCU through Vin vs USB

I am having a situation with my ESP32S Node MCU that I can't figure out. I uploaded a sketch to my MCU that will blink the blue LED connected to GPIO 2 every x number of seconds. Here is the sketch <...
1 vote
1 answer
96 views

Sanity checking an LM2596-ADJ constant current supply design for driving LEDs

I've designed, in simulation, an adjustable constant-current supply based on an LM2596-ADJ buck converter IC. I chose STW8B12C LEDs for simulation because three of them in series roughly matches up ...
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1 vote
2 answers
46 views

Selecting capacitor and inductor for adjustable buck converter

I'm trying to understand how to choose the right inductor for a buck converter that can produce different output voltages. When using an LM2596 I can add a potentiometer into feedback loop to produce ...
3 votes
0 answers
65 views

Output voltage not stable - What is compensation with respect to DC-DC (buck converter)?

EDITS: Input voltage range: 24V to 48V. Changing the load current from 0.38A to 1.018A increases the mean output voltage from 12.779V to 13.26V. The supply should be producing 12.5V. I'm using this ...
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11 votes
4 answers
798 views

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 ...
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5 votes
1 answer
84 views

Driving MOSFETs with the IR2104 for a buck converter doesn't give good results

I have been trying to create a buck converter with the IR2104 and two TK2R4A08QM transistors, but it seems that the high side MOSFET can't cope with the load and gets too hot. I probed the gate ...
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0 votes
2 answers
123 views

Buck converter and resistive wire

I'd like to ask about my circuit. It is a variable buck converter operated by an Arduino. At the end the 22 Ω resistor is resistive wire supposed to get hot because of the current. One thing that ...
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0 votes
2 answers
73 views

What is the mode of MOSFET or BJT in buck converter?

I want to implement buck converter with conventional design (not synchronous etc) like below. And I want to implement the converter for two cases. One is to use BJT as switching device and another is ...
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0 answers
38 views

Buck and boost converter

I want to make an energy control system on a stationary bike. The main input comes from a generator and the secondary input comes from a 6 V battery. The voltage from the generator ranges from 1-10 V, ...
2 votes
4 answers
338 views

PCB design with buck converter evaluation

In my project I have a 15 V power supply and I have to step it down to 3.3 V and 5 V for to use with PCB components. At first I tried using an LDO, but it heated up too much, to a point where it ...
0 votes
2 answers
83 views

How can I keep the output voltage of my MPPT buck converter in my PV system constant while connected to the load (battery)? [closed]

I've designed a PV based solar charger controller using the MPPT algorithm to charge my 12 V tubular battery for a DC load. I need to keep the output voltage constant at 14.5 V to connect a 12 V ...
4 votes
2 answers
126 views

What is this ringing in the inductor current?

I am working on a buck-boost converter and I see this ringing in the inductor current. It happens on turn on of the high side FET (See attached Image). First of all is this ringing normal? Is there ...
1 vote
1 answer
96 views

Identity a QFN chip

I would appreciate your help in identifying an electronic chip in a QFN package with 24 pins that belongs to a Roland R-05 sound recorder. The component is located near the DC/battery input and I ...
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3 votes
1 answer
290 views

Confusion about feedback resistor values for buck converter

I'm making my first voltage regulation first with a buck converter, but I'm having some trouble making sense of the following datasheet. https://www.ti.com/lit/ds/symlink/tps560200.pdf So I've made ...
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0 votes
3 answers
155 views

Are linear voltage regulators more efficient than switching regulators at very light loads?

I'm planning to make a battery application with a PIR sensor. The sensor consumes 70 μA and will be supplied with 4-5 V. I have two Li-ion batteries in series which gives around 8-9 V in total. I have ...
0 votes
1 answer
44 views

On-Time Control for Buck Converter

Can someone explain how they got equation 5.1. Why is the output voltage of their buck look like an equation for an non-inverting op-amp amplifying a Vref?
1 vote
3 answers
114 views

Buck converter adjustable output-voltage using digital potentiometer [closed]

I am trying to design a buck converter using an LM2576HV (Vref: 1.23 V) and a digital potentiometer (input: 48 V, output: 0 to 48 V, Imax= 3 A). The digital potentiometer with the highest supply ...
2 votes
2 answers
140 views

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 ...
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0 votes
1 answer
49 views

Driving a motor using a MOSFET, Raspberry 4b, and a converter

Edit: I was using a wrong MOSFET both IRF740 and IRF530 have gate to source voltage around 20 V and I used 3.3 V which is too low. Next time look ones with 3.3 V. I am designing a circuit for driving ...
-1 votes
1 answer
63 views

Buck converter load voltage drop

I'm creating a buck converter from a NE555 and LM358 (feedback loop) for powering a tablet motherboard. (This is a learning experience for me, don't want to use an off-the-shelf board.) Here is the ...
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2 answers
58 views

Why does low DC gain move an integrator pole?

The author is describing a voltage-mode buck control loop. In particular, he is describing PI compensation. The line I have highlighted is where he mentions 'In the simulation results, the dominant ...
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0 answers
48 views

Synchronous buck - "Inverse" current in the lower switch

I am referring to the typical synchronous buck architecture: simulate this circuit – Schematic created using CircuitLab The cycle starts with M1 conducting and inductor current increasing (I_L &...
4 votes
1 answer
109 views

Peak current mode control question

I read two different figures about the peak current mode control block diagram, and I am confused about one thing, please see the below two figures. In this figure, voltage loop output is connected to ...
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0 votes
0 answers
85 views

DC-DC buck converter inrush start on voltage

I started to examine the behavior of the converters on my custom board. The input to the converter comes from an external supply with a voltage of 20 V, the required output voltage is ~12 V. When I ...
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0 votes
1 answer
47 views

LM2596S heating up and drawing current

I am trying to generate -7 V/1.3 A and +7 V/1.3 A, using two LM2596S, from a 12 V voltage. The positive voltage is fine, but the negative one doesn't work. The first time I apply voltage to the ...
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2 votes
2 answers
240 views

Flybuck converter at high power

It is said that the flybuck topologies are cheaper than the flyback topologies. This is due to the fact that there is no need to have an optocoupler, the regulation is said to be simpler and probably ...
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-1 votes
2 answers
49 views

12 V, 3 A to buck converter or linear voltage regulator for Arduino and other components?

I'm using a 12 V, 3 A wall charger to supply a project: The project includes a motor (which needs 12 V, 3 A), an Arduino, a servo, and some other components. Since I don't want to fry my electronics, ...
0 votes
1 answer
47 views

Small-Signal Modelling of Buck Control

In equation 3.7, why is the author using v_in and not v_in(s)?
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0 votes
2 answers
54 views

Buck converter voltage drop and brownout

I was trying to build a 24 V to 5 V buck converter to create a shield that would power my Raspberry Pi4 via GPIO pins and also connect it to an accelerometer. The issue is, after powering it up, it ...
3 votes
1 answer
71 views

LM22673 diode selection

I'm fairly new to electronics, and in my project I'm using LM22673 as Buck Converter in this Diode selection parts this is given which is confusing for me. as Ultra-fast diodes can switch very fast, ...
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0 votes
2 answers
85 views

Design that outperforms buck converter

Above is quoted from here. I was just shocked to find out that the first image provides a much more efficient and simpler way to step down a voltage instead of using a buck converter circuit (second ...
0 votes
2 answers
39 views

Half-Bridge Switching Transition

Please see this video (from 6:43:40): https://youtu.be/FXbciGTDQuY?t=24223 They are explaining switching transitions in a synchronous buck converter. He says that when the high-side FET is on, the ...
0 votes
1 answer
48 views

Buck IC (XL4015) feedback logic

The datasheet for the XL4015 has the following information about the feedback loop: The threshold feedback voltage is 1.25V The switching frequency is 180Khz If the feedback voltage exceeds 3.3V, the ...
0 votes
0 answers
32 views

High-side MOSFET does not switch for load voltages larger than 5.8 V using IR2110

I am trying to make a battery charger using a buck converter and as a MOSFET driver I chose an IR2110. The voltage for VDD pin is 5 V and for Vcc and also for the MOSFET's drain I will supply from a ...
0 votes
1 answer
105 views

24V to 5V step down voltage regulator with LM2678 [closed]

Reference: https://www.ti.com/lit/ds/symlink/lm2678.pdf I have constructed the circuit above attempting to step down the DC voltage from 24V to 5V. But I keep getting 8.3V as the output voltage. It is ...
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1 vote
2 answers
62 views

Analyzing the feedback network of an LM2576/LM2596 regulator on this battery charger circuit

I'm trying to figure out how this 3A Battery Charger with Logic-Level Current Controls from Texas Instrument works. I know how output voltage feedback, current sampling, and op-amp section work. The ...
0 votes
0 answers
34 views

MPPT current limitation

I started to work on an MPPT project a couple of months ago. I have the first HW prototype (synchronous buck converter, current/voltage measurement, STM32 uC) and I am still fiddling with the SW side. ...
0 votes
2 answers
82 views

Output voltage of a step-down voltage regulator (or buck converter)

I've the following step-down regulator: and I'm wondering how to get the following formula for the output voltage: $$ V_{OUT} = \frac{T_{ON}}{T_{ON} + T_{OFF}} \, V_{IN} $$ I calculated the current ...
1 vote
1 answer
57 views

DC-DC converter circuit LM5164

I would like to build a DC-DC converter circuit using EasyEDA that can output about 80V from 7 Nissan Leaf battery modules that are about 55V nominal. I am looking at the datasheet for the LM5164 and ...
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0 votes
2 answers
144 views

24V to 5V Step Down - What did I do wrong?

I'm new to this and trying to understand what I did wrong. I designed a 24V to 5V buck step down around the XL2576S-5.0E1 (at least, I thought I did) — however my 5V out still produces 24V. I'm ...
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1 vote
1 answer
36 views

Determine the min/max resistance of an SMD variable resistor

I want to determine my minimum and maximum resistance rating for my variable resistor but failed to find the relevant information in the datasheet (this might be an issue more 'noobs' might have, ...
-2 votes
2 answers
96 views

Average voltage in PWM?

I have a doubt regarding average PWM voltage. Let's take a buck convertor with Vin=10V, Vout=5V. With this we can determine the duty cycle of PWM needs to be 50%. Thus means the MOSFET of the buck is ...
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1 vote
1 answer
54 views

12V on 24V PSU with Buck and Resistor

I have a 0.08A 12V fan that I'd like to run on a 24V PSU. I have a 1/4W resistor kit with several different resistor values and a max input 23V buck converter. Can I add a resistor in series before ...
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