AAT1162 Ver la hoja de datos (PDF) - Skyworks Solutions

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Fabricante

AAT1162

12V, 1.5A Step-Down DC/DC Converter

Skyworks Solutions 

DATA SHEET

AAT1162

12V, 1.5A Step-Down DC/DC Converter

Design Example

Specifications

VOUT

VIN

FOSC

TAMB

5V @ 1.5A, Pulsed Load ILOAD = 1.5A

12V nominal

800kHz

85°C in TDFN34-16 Package

Output Inductor

L=

VOUT

3.3

· 3.8µH = 5.75µH; use 4.7µH (see Table 2)

ΔIL = 0.32 · ILOAD = 480mA

For Cooper Bussman inductor DR73-4R7-R 4.7μH DCR = 29.7mW max.

ΔI1 =

VOUT

L1 ⋅ FOSC

⋅

⎛⎝1

-

VO1

VIN

⎞

⎠

=

5V

4.7µH ⋅ 800kHz

⋅

⎛⎝1

-

5V ⎞

12V⎠

=

480mA

IPK1

=

ILOAD

+

ΔI1

2

=

1.5A

+

0.480A

=

1.98A

PL1

=

I2

LOAD

⋅

DCR

=

3A2

⋅

13mΩ

=

117mW

Output Capacitor

VDROOP = 0.2V

COUT

= 3 · ΔILOAD

VDROOP · FOSC

=

3 · 1.5A

0.2V · 800kHz

= 28µF; use 22µF

I = RMS(MAX)

1 · (VOUT) · (VIN(MAX) - VOUT) = 1 ·

2· 3

L · FOSC · VIN(MAX)

2· 3

5V · (12V - 5V)

4.7µH · 800kHz · 12V

= 139mArms

Pesr = esr · IRMS2 = 5mΩ · (277mA)2 = 384µW

Input Capacitor

Input Ripple VPP = 50mV

1

1

CIN =

⎛

⎝

VPP

ILOAD

-

ESR⎞⎠ · 4

· FOSC

=

⎛ 50mV

⎝ 1.5A

- 5mΩ⎞⎠ · 4 · 800kHz

= 11µF; use 10µF

I = RMS(MAX)

ILOAD

2

=

0.75Arms

P = esr · IRMS2 = 5mΩ · (0.75A)2 = 2.81mW

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

16

201998B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013

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