AAT1143IJS-2.5-T1 View Datasheet(PDF) - Skyworks Solutions
Part Name
Description
MFG CO.
'AAT1143IJS-2.5-T1' PDF : 19 Pages View PDF
DATA SHEET
AAT1143
1MHz 400mA Step-Down Converter
Figure 2: AAT1143 Evaluation Board
Top Side.
Figure 3: Exploded View of Evaluation
Board Top Side Layout.
Figure 4: AAT1143 Evaluation Board
Bottom Side.
Adjustable Output Resistor Selection
For applications requiring an adjustable output voltage,
the 0.6V version can be externally programmed. Resistors
R1 and R2 of Figure 5 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 sug-
gested 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 sensi-
tive to external noise and interference. Table 2 summa-
rizes the resistor values for various output voltages with
R2 set to either 59k for good noise immunity or 221k
for reduced no load input current.
R1
=
⎛ VOUT
⎝ VREF
-1⎞⎠
·
R2
=
⎛ 1.5V
⎝ 0.6V
-
1 ⎞⎠
·
59kΩ
=
88.5kΩ
The adjustable version of the AAT1143, combined with
an external feedforward capacitor (C4 in Figure 1),
delivers enhanced transient response for extreme pulsed
load applications. The addition of the feedforward
capacitor typically requires a larger output capacitor C1
for stability.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
12
201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013
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