AAT1106 Ver la hoja de datos (PDF) - Skyworks Solutions
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AAT1106 Datasheet PDF : 19 Pages
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Applications Information
Figure 1 shows the basic application circuit of AAT1106.
VIN
2.5V to 5.5V
C1
4.7μF
IN
LX
AAT1106
FB
EN
GND
L1
2.2μH
C2
22pF
R2
634K
R1
316K
VOUT
1.8V
C3
10μF
Figure 1: Basic Application Circuit
Setting the Output Voltage
For applications requiring an adjustable output voltage,
the AAT1106-0.6 can be externally programmed.
Resistors R1 and R2 of Figure 2 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 R1 is 59kΩ. 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 sum-
marizes the resistor values for various output voltages
with R1 set to either 59kΩ for good noise immunity or
316kΩ for reduced no load input current.
The AAT1106, combined with an external feed forward
capacitor (C2 in Figure 2), delivers enhanced transient
response for extreme pulsed load applications. The addi-
tion of the feed forward capacitor typically requires a
larger output capacitor C3 for stability. The external
resistor sets the output voltage according to the follow-
ing equation:
VOUT
= 0.6V · ⎛⎝1 +
R2
R1
or
[ R2 =
⎛ VOUT
⎝ 0.6V
-1
· R1
DATA SHEET
AAT1106
600mA 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
R1 = 59k
R2 (k)
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
267
R1 = 316k
R2 (k)
105
158
210
261
316
365
422
475
634
655
732
1000
1430
Table 1: Resistor Selection for Output Voltage
Setting; Standard 1% Resistor Values
Substituted Closest to the Calculated Values.
Inductor Selection
For most designs, the AAT1106 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 · ∆IL · 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 35% of the maximum load current
600mA, or IL = 210mA.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201970B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 15, 2013
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