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Buck/Boost Converter

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A DC DC Converter capable of buck/ Boost input voltage

11 Ratings



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Below 50 % duty cycle it steps down the DC Voltages and from 50 -99% of duty cycle it steps up the input voltage

Comments and Ratings (25)

yasmine amara

Dear sir Hadded
can you help me out how to construct (boost converter with a constant output voltage with variable input voltage) if u have this circuit simulink send me

kh asnoune

thanks hadded,please can u help me; i need a simulation of closed loop of buck boost cnverter. thanks


Nelge (view profile)


omar kanaan

Pls can u help me with an mdl file of a boost converter with a constant output voltage and possible varing input voltage. My email is for ex from 10 to 20 it give 15 v


Dear Sir Hadeed

Regarding the buck boost converter, when they say you supply/need 50W and you use PWM do I still use the values you gave bellow or its another case, should I email my project so you can assist?

MR Maluleke

kamilu sanusi

this is indeed helpful. thank u Hadeed Sher,
Pls can u help me with an mdl file of a boost converter with a constant output voltage and possible varing input voltage. My email is
Thank you

Hari Sankar

Dear Hadeed sher
but i have problem with simulation of my circuit, can i send my project to you? Please help me

Hadeed Sher

Hadeed Sher (view profile)

Dear Hari Shankar,

Here are the required values.
Rl=1 ohm
C=1500Micro Farad
Rload=10 ohm

Hari Sankar

What is the amount of L, C, RL,Rc, and R load, please answer me.....

zaid trad



i made my buck boost circuit but i am having problem on what values for L and C i have to put in order to get the correct out put graphs


Hadeed Sher

Hadeed Sher (view profile)

Dear wassay, hope that you have the answer of the question

Wasay Alvi

Sir Hadeed sir,
I am designing MPPT controller for solar pv panels, kindly i wanted to ask you about the operation of Cuk converter the out put of cuk is also negative. so is there any method that the duty cycle of dc-dc converters automatically changes with the time? like i have seen in some reference papers that they do some feed back to the controller to change the duty cycle with time.. plz need your help regarding this .. i would really appreciate ur effort.

Hadeed Sher

Hadeed Sher (view profile)

there are several books on this topic. generally this circuit is not used for BUCK/BOOST operation. designers use regular topologies of buck and boost for these specific tasks. The answer to this question is very well discussed in the book i mentioned above.

I have a small query reg Buck Boost converter,

1. If mode of operation is Buck , let i/p vol is 200 V , my doubt is what the minimum voltage we can get , and how this will be decided in practical ckts as well as simulation ckt

In similarly

2. If mode of operations is Boost , let Input vol 24 V , then what max output voltage can be obtained at o/p , what factors affect this range of o/p voltage

Thank you sir

Hadeed Sher

Hadeed Sher (view profile)

well if you need a positive voltage then add an other BUCK/BOOST circuit with 52% duty cycle (Since at 50 % due to losses in circuit elements output will be slightly less then input).
Secondly the circuit elements needs redesigning if you disturb the input voltages to a very large extent. Theoretically it must give us infinite output voltage at 100 % duty cycle but it never happens because of the fact that practically there are always losses in circuit elements

Thank you for the realy reply

and Let me correct .........

What changes to be done in the circuit if i want +ve o/p voltage ...

I simulated ur ckt for boost operation of 24 V input to 200 V output by setting duty cycle 89.23% (calculated from Vo/p / Vin = D/(1-D)) ...........

I got the output of -157 V , where i were wrong ......Plz help me.

Thank You

Hadeed Sher

Hadeed Sher (view profile)

@manjunath: This type of DC DC converter is also known as polarity inverting converter(For more information on DC DC Converter please refer to Switching power supply design by Abraham I pressman). The output is always inverted .So there is nothing wrong with this circuit.

Good file.........
i simulated it but , it is giving -ve output voltages in both buck and boost modes , plz check it once

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