RT8271
Typical Application Circuit
V
IN
4.75V to 24V
Chip Enable
C
IN
10µF/25V
VIN
BOOT
RT8271
SW
EN
SS
GND
FB
C
C
1.5nF
COMP
R
C
15k
R2
10k
C
BOOT
L1
10nF 4.7µH
D1
B230A
R1
16.9k
V
OUT
2.5V
C
OUT
22µF/6.3V
C
SS
10nF
C
P
NC
Table 1. Recommended Component Selection
V
OUT
(V)
R1 (kΩ)
R2 (kΩ)
R
C
(kΩ)
C
C
(nF)
L (μH)
C
OUT
(μF)
15
10
8
5
3.3
2.5
1.8
1.2
154
100
76.8
44.2
25.5
16.9
9.53
3
10
10
10
10
10
10
10
10
68
49.9
49.9
33
22
15
12
12
0.56
0.82
1
1.2
1.5
1.5
1.5
1.5
22
15
10
6.8
4.7
4.7
2.2
2.2
22
22
22
22
22
22
22
22
Function Block Diagram
VIN
V
CC
1µA
EN
10k
VA V
CC
-
+
1V
Shutdown
Comparator
V
CC
10µA
SS
+
+
EA
-
Gm = 920µA/V
0.92V
Foldback
Control
0.5V
+
-
UV
Comparator
Internal
Regulator
Oscillator
1.2MHz/440kHz
Current Sense
Slope Comp Amplifier
+
-
VA
BOOT
SW
3V
+
-
Current
Comparator
Logic
GND
FB
COMP
www.richtek.com
2
DS8271-02 March 2011
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
