AAT1153IDE-0.6-T1 查看數據表（PDF） - Skyworks Solutions

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AAT1153IDE-0.6-T1

2A Step-Down Converter

Skyworks Solutions 

Applications Information

VIN 2.5V-5.5V

C1

22μF

1

EN

LX 8

2 IN

LX 7

3 AIN AAT1153-0.6 FB 5

6 AGND

4 AGND

PGND 10

PGND 9

L1

2.2μH

C3

22pF

VOUT

1.8V, 2A

R1

634kΩ C2

22μF

R2

316kΩ

Figure 1: Basic Application Circuit.

Setting the Output Voltage

Figure 1 shows the basic application circuit for the

AAT1153. The AAT1153 can be externally programmed.

Resistors R1 and R2 in Figure 1 program the output to

regulate at a voltage higher than 0.6V. To limit the bias

current required for the external feedback resistor string

while maintaining good noise immunity, the minimum

suggested value for R2 is 59k. Although a larger value

will further reduce quiescent current, it will also increase

the impedance of the feedback node, making it more

sensitive to external noise and interference. Table 1

summarizes the resistor values for various output volt-

ages with R2 set to either 59k for good noise immunity

or 316k for reduced no load input current.

The AAT1153, combined with an external feed forward

capacitor (C3 in Figure 1), delivers enhanced transient

response for extreme pulsed load applications. The addi-

tion of the feed forward capacitor typically requires a

larger output capacitor C2 for stability. The external

resistor sets the output voltage according to the follow-

ing equation:

VOUT = 0.6V ·

⎛⎝1 +

R1 ⎞

R2 ⎠

R1 =

⎛

⎝

VOUT

0.6V

-

1 ⎞⎠

· R2

Table 1 shows the resistor selection for different output

voltage settings.

DATA SHEET

AAT1153

2A Step-Down Converter

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

3.3

R2 = 59k

R1 (k)

19.6

29.4

39.2

49.9

59.0

68.1

78.7

88.7

118

124

137

187

267

R2 = 316k

R1 (k)

105

158

210

261

316

365

422

475

634

655

732

1000

1430

Table 1: Resistor Selections for Different Output

Voltage Settings (Standard 1% Resistors

Substituted For Calculated Values).

Inductor Selection

For most designs, the AAT1153 operates with inductor

values of 1μH to 4.7μH. Low inductance values are

physically smaller but require faster switching, which

results in some efficiency loss. The inductor value can

be derived from the following equation:

L = VOUT · (VIN - VOUT)

VIN · ΔIL · fOSC

Where IL is inductor ripple current. Large value induc-

tors lower ripple current and small value inductors result

in high ripple currents. Choose inductor ripple current

approximately 30% of the maximum load current 2A, or

ΔIL = 600mA

For output voltages above 2.0V, when light-load effi-

ciency is important, the minimum recommended induc-

tor is 2.2μH.

Manufacturer’s specifications list both the inductor DC

current rating, which is a thermal limitation, and the

peak current rating, which is determined by the satura-

tion characteristics. The inductor should not show any

appreciable saturation under normal load conditions.

Some inductors may meet the peak and average current

ratings yet result in excessive losses due to a high DCR.

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

201992B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 18, 2013

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