AS1341_13 Datasheet, PDF (10/18 Pages) ams AG – 650mA, Ul t ra low Ripple Step Down DC/DC Conver ter

AS1341
Datasheet - Application Information
9 Application Information
9.1 Adjusting Output Voltage
The AS1341 feedback input features dual-mode operation. Connect FB to GND for the 5.0V preset output voltage (see Figure 21 on page 8).
Adjust the output voltage by connecting a voltage-divider from the output to GND (see Figure 22).
Figure 22. Adjustable Output Voltage Circuit
VIN
4.5V to 20V
CIN
5
IN
7
SHDNN
6
ILIMIT
2
GND
AS1341
4
LX
D1
3
POK
1
FB
8
OUT
L1
RPULL
1.25V to VIN
+
COUT
R1
R2
Select a value for R2 between 10k and 1MΩ.
Calculate R1 as:
Where:
VFB = 1.25V.
VOUT may range from 1.25V to VIN.
R₁
=
R₂
⋅


V_{----O----U----T-}
V_FB
–
1_
9.2 Negative Output Voltage
VIN may range from 4.5V to (20V-VOUT). Therefore the maximum negative output voltage is -15V.
Figure 23. Adjustable Negative Output Voltage Circuit
Indicates High-Power Trace
(EQ 2)
VIN
4.5V to (20V-VOUT)
CIN
5
IN
7
SHDNN
6
ILIMIT
2
GND
AS1341
L1
4
LX
3
D1
POK
1
FB
8
OUT
R1
+
COUT
R2
VOUT = -1.25V to -15V
Indicates High-Power Trace
www.ams.com/DC-DC_Step-Up/AS1341
Revision 1.09
10 - 18