AAT2146W Datasheet, PDF (12/18 Pages) Skyworks Solutions Inc. – Low-Noise, Fast Transient 600mA Step-Down Converter

DATA SHEET
AAT2146W
Low-Noise, Fast Transient 600mA Step-Down Converter
Figure 2: AAT2146W Evaluation Board
Component Side Layout.
Figure 3: Exploded View of AAT2146W
Evaluation Board Component Side Layout.
Figure 4: AAT2146W Evaluation Board
Solder Side Layout.
Adjustable Output Resistor Selection
Feedback 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 resis-
tor 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, mak-
ing it more sensitive to external noise and interference.
Table 2 summarizes the resistor values for various out-
put voltages with R2 set to either 59k for good noise
immunity or 221k for reduced no load input current.
R1
=
⎛ ^VOUT
⎝ V_REF
-1^⎞⎠
·
R2
=
⎛ ^1.5V
⎝ 0.6V
-
1 ^⎞⎠
·
59kΩ
=
88.5kΩ
The AAT2146W combined with an external feedforward
capacitor (C4 in Figure 5), delivers enhanced transient
response for extreme pulsed load applications.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
12
202008A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 28, 2012