LTC3624-2 datasheet(16/20 Pages) LINER

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LTC3624/LTC3624-2

36242fd

For more information www.linear.com/LTC3624

Design Example

Asadesignexample,considerusingtheLTC3624/LTC3624-2

in an application with the following specifications:

VIN = 10.8V to 13.2V

VOUT = 3.3V

IOUT(MAX) = 2A

IOUT(MIN) = 0A

fSW = 2.25MHz

Because efficiency and quiescent current are important at

both 500mA and 0A current states, Burst Mode operation

will be utilized.

Given the internal oscillator of 2.25MHz, we can calcu-

late the inductor value for about 40% ripple current at

maximum VIN:

L =

3.3V

2.25MHz •0.8A









1–

3.3V

13.2V









=1.38µH

Given this, a 1.5µH inductor would suffice.

COUT will be selected based on the ESR that is required to

satisfy the output voltage ripple requirement and the bulk

capacitance needed for loop stability. For this design, a

47µF ceramic capacitor will be used.

CIN should be sized for a maximum current rating of:

IRMS =2A

3.3V

13.2V









13.2V

3.3V

–1







1/2

= 0.86A

Bypassing the VINpintogroundwith10µFceramiccapaci-

tors is adequate for most applications.

applicaTions inForMaTion

Figure 3a. Sample PCB Layout-Top Side

Figure 3b. Sample PCB Layout-Bottom Side

TOP LAYER

GND

36242 F03a

GND

CIN

VIN

VOUT

COUT

C_INTVCC

LTC3624

BOTTOM LAYER

GND

36242 F03b

GND

CIN

VIN

VOUT

COUT

(OPT)

COUT

(OPT)

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