LM3524DM datasheet(15/29 Pages) TI

Part #	LM3524DM

Description	Regulating Pulse Width Modulator

PDF	29 Pages

Scroll/Zoom	100%

Manufacturer	TI [Texas Instruments]

Direct Link	http://www.ti.com

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15 / 29 page

LM2524D, LM3524D

www.ti.com

SNVS766E – JUNE 2009 – REVISED MAY 2013

Figure 23. Relation of Switch Timing to Inductor Current in Step-Down Regulator

(4)

Neglecting VSAT, VD, and settling ΔIL

+ = ΔI

−;

(5)

where T = Total Period

The above shows the relation between VIN, Vo and duty cycle.

(6)

as Q1 only conducts during tON.

(7)

The efficiency,

η, of the circuit is:

(8)

ηMAX will be further decreased due to switching losses in Q1. For this reason Q1 should be selected to have the

maximum possible fT, which implies very fast rise and fall times.

Calculating Inductor L1

(9)

Since

ΔIL+ = ΔIL

− = 0.4I

Solving the above for L1

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LM3524DM Datasheet(PDF) 15 Page - Texas Instruments