What does Ipk mean in the Boost Peak Switch Current formula?

Ipk is Peak switch/inductor current (A).

Boost Peak Switch Current

Q: How do you calculate Boost Peak Switch Current?

Use the formula Ipk = Iout/(1 − D) + ΔIL/2. The peak current in a boost converter’s switch and inductor is the average inductor current (the output current divided by 1 − D) plus half the ripple. Enter the values you know in the calculator above and it solves for the remaining variable.

Q: What is the formula for Boost Peak Switch Current?

The Boost Peak Switch Current formula is Ipk = Iout/(1 − D) + ΔIL/2, where Ipk—Peak switch/inductor current (A); Iout—Output (load) current (A); D—Duty cycle (0–1); ΔIL—Peak-to-peak ripple current (A).

Ipk = Iout/(1−D) + ΔIL/2

Quick answer

This calculator solves Ipk = Iout/(1 − D) + ΔIL/2 for Peak Current. With Output Current 4.4 A, Duty Cycle 50 %, Ripple Current 20 mA, the result is 8.81 A. It solves in 4 directions, so you can enter the values you have and get the one you need.

Calculator

Output Current

Duty Cycle

Ripple Current

Peak Current (A)

—

Formula

Ipk = Iout/(1 − D) + ΔIL/2

Description

The peak current in a boost converter’s switch and inductor is the average inductor current (the output current divided by 1 − D) plus half the ripple. This peak sets the saturation rating of the inductor and the current rating of the MOSFET and diode. Underestimating it leads to inductor saturation and runaway current.

Variables

Ipk — Peak switch/inductor current (A)
Iout — Output (load) current (A)
D — Duty cycle (0–1)
ΔIL — Peak-to-peak ripple current (A)

Practical Notes

The average inductor current Iout/(1−D) rises steeply as D approaches 1, which is why high step-up ratios demand large, low-saturation inductors and high-current switches.

Symbols and units

Symbol	Meaning	Default unit	Accepted units
Ipk	Peak Current	A	pA, nA, µA, mA, A, kA
Iout	Output Current	A	pA, nA, µA, mA, A, kA
D	Duty Cycle	—	—, %
dIL	Ripple Current	mA	pA, nA, µA, mA, A, kA

Step by step

1. What you know: Output Current 4.4 A, Duty Cycle 50 %, Ripple Current 20 mA
2. The relation: Ipk = Iout/(1 − D) + ΔIL/2
3. Substitute: Iout = 4.4 A, D = 50 %, dIL = 20 mA
4. Result: Peak Current = 8.81 A

Worked examples

Minimum range

Given: Output Current 4.4 mA, Duty Cycle 2.5 %, Ripple Current 100 µA

Result: Peak Current = 4.563 mA

Low range

Given: Output Current 44 mA, Duty Cycle 25 %, Ripple Current 1 mA

Result: Peak Current = 59.17 mA

Typical

Given: Output Current 4.4 A, Duty Cycle 50 %, Ripple Current 20 mA

Result: Peak Current = 8.81 A

High range

Given: Output Current 0.22 kA, Duty Cycle 0.8, Ripple Current 0.5 A

Result: Peak Current = 1.1 kA

Maximum range

Given: Output Current 2.2 kA, Duty Cycle 8, Ripple Current 5 A

Result: Peak Current = -0.3118 kA

Solving for each variable

Solve for Peak Current

Output Current 4.4 mA, Duty Cycle 2.5 %, Ripple Current 100 µA → 4.563 mA

Solve for Output Current

Peak Current 2 mA, Duty Cycle 2.5 %, Ripple Current 100 µA → 1.901 mA

Solve for Ripple Current

Peak Current 2 mA, Output Current 4.4 mA, Duty Cycle 2.5 % → -5.026 mA

Solve for Duty Cycle

Peak Current 2 mA, Output Current 4.4 mA, Ripple Current 100 µA → -1.256

How Peak Current changes with Output Current

Output Current (input)	Peak Current (result)
0.44 A	0.89 A
1.1 A	2.21 A
2.2 A	4.41 A
3.3 A	6.61 A
4.4 A	8.81 A
6.6 A	13.21 A
8.8 A	17.61 A
17.6 A	35.21 A
30.8 A	61.61 A
44 A	88.01 A

The same result in other units

Unit	Value
µA	8810000
mA	8810
A	8.81
kA	0.00881

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Frequently asked questions

How do you calculate Boost Peak Switch Current?

Use Ipk = Iout/(1 − D) + ΔIL/2. With Output Current 4.4 A, Duty Cycle 50 %, Ripple Current 20 mA, Peak Current works out to 8.81 A.

How do you calculate boost average current peak current?

Rearrange for Peak Current: with Output Current 44 mA, Duty Cycle 25 %, Ripple Current 1 mA, Peak Current is 59.17 mA.

What is the formula for Boost Peak Switch Current?

The formula is Ipk = Iout/(1 − D) + ΔIL/2. The peak current in a boost converter’s switch and inductor is the average inductor current (the output current divided by 1 − D) plus half the ripple.

How do you find Output Current when you know the other values?

Rearrange for Output Current: with Peak Current 2 mA, Duty Cycle 2.5 %, Ripple Current 100 µA, Output Current is 1.901 mA.

How do you find Ripple Current when you know the other values?

Rearrange for Ripple Current: with Peak Current 2 mA, Output Current 4.4 mA, Duty Cycle 2.5 %, Ripple Current is -5.026 mA.

What units does Boost Peak Switch Current use?

Peak Current is shown in µA, mA, A, kA. Values are held in SI base units internally, so you can mix prefixes without converting by hand.

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