Fujitsu MB39A104 manual Peak-to-peak value ΔIL

MB39A104

To determine whether the current through the inductor is within rated values, it is necessary to determine the peak value of the ripple current as well as the peak-to-peak values of the ripple current that affect the output ripple voltage. The peak value and peak-to-peak value of the ripple current can be determined by the following formulas.

Peak value : IL

IL	≥ IO +		VIN − VO		ton
			2L
Peak-to-peak value : ΔIL
ΔIL	=	VIN − VO		ton
			L

Example: Using the CDRH104R-150

15 ∝H (allowable tolerance ±30%) , rated current = 3.6 A

Peak value:

CH1

IL ≥ IO +	VIN − VO	ton
	2L
≥ 3 +	19 − 5		1		⋅ 0.263
			⋅
	2 ⋅ 15 ⋅ 10−6			500 ⋅ 103

≥3.25 A

CH2

IL ≥ IO +	VIN − VO	ton
	2L
≥ 3 +	19 − 3.3		⋅	1	⋅ 0.174
	2 ⋅ 15 ⋅ 10−6			500 ⋅ 103

≥3.18 A

Peak-to-peak value:

CH1

ΔIL =	VIN − VO		ton
	L
=	19 − 5	1			⋅ 0.263
		⋅
	15 ⋅ 10−6			500 ⋅ 103

=0.491 A

CH2

ΔIL =	VIN − VO		ton
	L
=	19 − 3.3	⋅	1		⋅ 0.174
	15 ⋅ 10−6			500 ⋅ 103

=0.364 A

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