AS1341 austriamicrosystems AG, AS1341 Datasheet - Page 10

• Manufacturer Part Number: AS1341
• Description: Step-Down Converter
• Manufacturer: austriamicrosystems AG

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AS1341
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
Adjusting Output Voltage
The AS1341 feedback input features dual-mode operation. Connect FB to GND for the 5.0V preset output voltage.
Adjust the output voltage by connecting a voltage-divider from the output to GND (Figure 4).
Figure 22. Adjustable Output Voltage Circuit
Select a value for R
Calculate R
Where:
V
V
Setting Current Limit
The AS1341 adjustable peak current limit is set by connecting ILIMIT as shown in
Table 4. Setting Peak Current Limit
The current limit chosen should reflect the maximum load current. The maximum output current is half of the peak cur-
rent limit. Choosing a lower current limit allows using an inductor with a lower current rating, however, it requires a
higher inductance
Inductor Selection
The AS1341 operates with a wide range of inductance values. For most applications, values between 10µH and 47µH
work best with the controller’s high switching frequency. Larger inductor values will reduce the switching frequency and
thereby improve efficiency and EMI.
Note: The four key factors in inductor selection are inductance value, saturation rating, series resistance, and size.
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FB
OUTPUT
= 1.25V.
Current Limit
1400mA
700mA
may range from 1.25V to VIN.
1
as:
4.5 to
20V
(see Inductor Selection on page 10)
2
C
between 10k and 1MΩ.
IN
ILIMIT Connected To
GND
SHDNN
IN
ILIMIT
GND
IN
5
7
6
2
AS1341
R
1
=
Revision 1.00
R
and does not allow for reduced inductor package size.
2
⋅
⎛
⎝
V
-------------- 1
V
OUT
FB
–
4
LX
3
POK
1
FB
8
OUT
⎞
⎠
D1
L1
R
PULL
Table
4.
Indicates High-Power Trace
R
R
1
2
+
C
OUT
1.25V
to V
IN
(EQ 2)
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