AAT1156(2005) Просмотр технического описания (PDF) - Advanced Analogic Technologies

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AAT1156
(Rev.:2005)

1MHz 700mA Step-Down DC-DC Converter

Advanced Analogic Technologies 

AAT1156

1MHz 700mA Step-Down DC-DC Converter

Design Example

Specifications

IOUT 0.7A

IRIPPLE 40% of Full Load at Max VIN

VOUT 2.5V

VIN 2.7V to 4.2V (3.6V nominal)

FS

1MHz

TAMB 85°C

Maximum Input Capacitor Ripple:

IRMS = IO ·

VO · ⎛1-

VIN ⎝

VO ⎞

VIN ⎠

= 0.34Arms,

VIN =

2x

VO

P = esr · IRMS2 = 5mΩ · 0.342 A = 0.6mW

Inductor Selection:

L=

VOUT

IO ⋅ k ⋅

F

⋅

⎛⎝1

-

VOUT⎞

VIN ⎠

=

2.5V

0.7A ⋅ 0.3 ⋅ 1MHz

⋅ ⎛⎝1 -

2.5V ⎞

4.2V⎠

= 4.82µH

Select Sumida inductor CDRH3D16 or CDRH4D28 4.7µH.

∆I =

VO

L⋅F

⋅

⎛⎝1

-

VO

VIN

⎞

⎠

=

2.5V

4.7µH ⋅ 1MHz

⋅ ⎛⎝1-

2.5V⎞

4.2V⎠

=

220mA

IPK

=

IOUT

+

∆I

2

=

0.7A

+

0.11A

=

0.81A

P = IO2 ⋅ DCR = (0.7A)2 ⋅ 80mΩ = 40mW

1156.2005.11.1.2

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