Critical Value of Capacitor for Buck Regulator Calculator

✖A Duty cycle or power cycle is the fraction of one period in which a signal or system is active in a voltage regulator circuit.ⓘ Duty Cycle [D]			+10% -10%
✖Critical Inductance refers to the minimum value of the inductance required in these converters to maintain continuous conduction mode (CCM) or continuous current flow through the inductor.ⓘ Critical Inductance [L_x]			+10% -10%
✖Frequency is the frequency at which a voltage regulator circuit or system tends to oscillate in the absence of any driving or damping force.ⓘ Frequency [f]			+10% -10%

✖Critical Capacitance in Buck is minimum value of capacitance in order to have a continuous current in the inductor and, therefore, maintain good regulation.ⓘ Critical Value of Capacitor for Buck Regulator [C_x(bu)]

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Critical Value of Capacitor for Buck Regulator

Formula

`"C"_{"x(bu)"} = (1-"D")/(16*"L"_{"x"}*"f"^2)`

Example

`"356.6913μF"=(1-"0.21")/(16*"0.113H"*("35Hz")^2)`

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Critical Value of Capacitor for Buck Regulator Solution

STEP 0: Pre-Calculation Summary

Formula Used

Critical Capacitance in Buck = (1-Duty Cycle)/(16*Critical Inductance*Frequency^2)
C_x(bu) = (1-D)/(16*L_x*f^2)
This formula uses 4 Variables

Variables Used

Critical Capacitance in Buck - (Measured in Farad) - Critical Capacitance in Buck is minimum value of capacitance in order to have a continuous current in the inductor and, therefore, maintain good regulation.
Duty Cycle - A Duty cycle or power cycle is the fraction of one period in which a signal or system is active in a voltage regulator circuit.
Critical Inductance - (Measured in Henry) - Critical Inductance refers to the minimum value of the inductance required in these converters to maintain continuous conduction mode (CCM) or continuous current flow through the inductor.
Frequency - (Measured in Hertz) - Frequency is the frequency at which a voltage regulator circuit or system tends to oscillate in the absence of any driving or damping force.

STEP 1: Convert Input(s) to Base Unit

Duty Cycle: 0.21 --> No Conversion Required
Critical Inductance: 0.113 Henry --> 0.113 Henry No Conversion Required
Frequency: 35 Hertz --> 35 Hertz No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

C_x(bu) = (1-D)/(16*L_x*f^2) --> (1-0.21)/(16*0.113*35^2)

Evaluating ... ...

C_x(bu) = 0.000356691349106014

STEP 3: Convert Result to Output's Unit

0.000356691349106014 Farad -->356.691349106014 Microfarad (Check conversion here)

FINAL ANSWER

356.691349106014 ≈ 356.6913 Microfarad <-- Critical Capacitance in Buck

(Calculation completed in 00.004 seconds)

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Created by Parminder Singh

Chandigarh University (CU), Punjab

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< 2 Buck Regulator Calculators

Critical Value of Capacitor for Buck Regulator

Go Critical Capacitance in Buck = (1-Duty Cycle)/(16*Critical Inductance*Frequency^2)

Critical Value of Inductor for Buck Regulator

Go Critical Inductance = ((1-Duty Cycle)*Resistance)/(2*Frequency)

Critical Value of Capacitor for Buck Regulator Formula

Critical Capacitance in Buck = (1-Duty Cycle)/(16*Critical Inductance*Frequency^2)
C_x(bu) = (1-D)/(16*L_x*f^2)

Explain Buck regulator operation?

When the switch in the buck regulator is on, the voltage that appears across the inductor is Vin - Vout. Using the inductor equations, the current in the inductor will rise at a rate of (Vin-Vout)/L. At this time the diode D is reverse biased and does not conduct.
When the switch opens, current must still flow as the inductor works to keep the same current flowing. As a result current still flows through the inductor and into the load. The diode, D then forms the return path with a current Idiode equal to Iout flowing through it.

With the switch open, the polarity of the voltage across the inductor has reversed and therefore the current through the inductor decreases with a slope equal to -Vout/L. It is also worth noting that the average input current is less than the average output current.

How to Calculate Critical Value of Capacitor for Buck Regulator?

Critical Value of Capacitor for Buck Regulator calculator uses Critical Capacitance in Buck = (1-Duty Cycle)/(16*Critical Inductance*Frequency^2) to calculate the Critical Capacitance in Buck, The Critical value of capacitor for Buck regulator formula is defined as the minimum value of capacitance in order to have a continuous current in the inductor and, therefore, maintain good regulation. Critical Capacitance in Buck is denoted by C_x(bu) symbol.

How to calculate Critical Value of Capacitor for Buck Regulator using this online calculator? To use this online calculator for Critical Value of Capacitor for Buck Regulator, enter Duty Cycle (D), Critical Inductance (L_x) & Frequency (f) and hit the calculate button. Here is how the Critical Value of Capacitor for Buck Regulator calculation can be explained with given input values -> 3.6E+8 = (1-0.21)/(16*0.113*35^2).

FAQ

What is Critical Value of Capacitor for Buck Regulator?

The Critical value of capacitor for Buck regulator formula is defined as the minimum value of capacitance in order to have a continuous current in the inductor and, therefore, maintain good regulation and is represented as C_x(bu) = (1-D)/(16*L_x*f^2) or Critical Capacitance in Buck = (1-Duty Cycle)/(16*Critical Inductance*Frequency^2). A Duty cycle or power cycle is the fraction of one period in which a signal or system is active in a voltage regulator circuit, Critical Inductance refers to the minimum value of the inductance required in these converters to maintain continuous conduction mode (CCM) or continuous current flow through the inductor & Frequency is the frequency at which a voltage regulator circuit or system tends to oscillate in the absence of any driving or damping force.

How to calculate Critical Value of Capacitor for Buck Regulator?

The Critical value of capacitor for Buck regulator formula is defined as the minimum value of capacitance in order to have a continuous current in the inductor and, therefore, maintain good regulation is calculated using Critical Capacitance in Buck = (1-Duty Cycle)/(16*Critical Inductance*Frequency^2). To calculate Critical Value of Capacitor for Buck Regulator, you need Duty Cycle (D), Critical Inductance (L_x) & Frequency (f). With our tool, you need to enter the respective value for Duty Cycle, Critical Inductance & Frequency and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

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