AAT1275
Boost Converter with USB Power Switch
VIN
R1
10K
U1
AAT1275
L1 2.2µH
4
1
8
SW
LIN
FLT
FLT
6
OUT2
VO2
VO1
R4
7
5
J5
GND
SET OUT1
16.9kΩ
R2
432k
10
12
GND
VCC
EN
FB
C1
4.7µF
C2
4.7µF
11
2
9
3
10V
VIN
VIN PGND
R3
C6
C3
4.7µF
10V
59k
120µF
CCase
GND
VIN
GND
3
2
1
Enable
Figure 3: AAT1275 Evaluation Board Schematic
Step-Up Converter Design Example
Specifications
VOUT = 5V
IOUT = 300mA
VIN = 2.7V to 4.2V (3.6V nominal)
TAMB = 50°C
Output Inductor
VOUT - VIN(MIN)
VOUT
5V - 2.7V
5V
DMAX
=
=
= 0.46
From the characterization curves, the switching frequency at room temperature with a 300mA load and 2.2µH
inductor is about 800kHz.
1275.2007.01.1.3
15