AAT1143 데이터 시트보기 (PDF) - Skyworks Solutions

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AAT1143

1MHz 400mA Step-Down Converter

Skyworks Solutions 

VOUT (V)

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.8

1.85

2.0

2.5

R2 = 59kΩ

R1 (kΩ)

19.6

29.4

39.2

49.9

59.0

68.1

78.7

88.7

118

124

137

187

R2 = 221kΩ

R1 (kΩ)

75

113

150

187

221

261

301

332

442

464

523

715

Table 2: Adjustable Resistor Values For Use With

0.6V Step-Down Converter.

DATA SHEET

AAT1143

1MHz 400mA Step-Down Converter

Thermal Calculations

There are three types of losses associated with the

AAT1143 step-down converter: switching losses, con-

duction losses, and quiescent current losses. Conduction

losses are associated with the RDS(ON) characteristics of

the power output switching devices. Switching losses are

dominated by the gate charge of the power output

switching devices. At full load, assuming continuous con-

duction mode (CCM), a simplified form of the losses is

given by:

PTOTAL

=

IO2

·

(RDS(ON)H

·

VO

+ RDS(ON)L

VIN

·

[VIN

-

VO])

+ (tsw · FS · IO + IQ) · VIN

IQ is the step-down converter quiescent current. The

term tsw is used to estimate the full load step-down con-

verter switching losses.

1

2

3

Enable

VIN

C4

100pF

VOUT =1.8V

R1

118k

L1

4.7μH

C1

10μF

C3

n/a

R2

59k

U1

AAT1143

1

8

EN PGND

2

7

OUT PGND

3

6

VIN PGND

4

5

LX AGND

C2

4.7μF

GND

GND2

LX

U1 AAT1143 SC70JW-8

L1 CDRH3D16-4R7

C2 4.7μF 10V 0805 X5R

C1 10μF 6.3V 0805 X5R

Figure 5: AAT1143 Adjustable Evaluation Board Schematic.

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

201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013

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