Step-Down Controllers with
Synchronous Rectifier for CPU Power
____________________________________________Application Circuits (continued)
MAX797
INPUT
4.5V
TO 30V
STANDARD 3.3V
CIRCUIT
+3.3V
MAIN OUTPUT
V+
MAIN
3.3V
OUTPUT
(CSL)
REF
(2.505V)
VL (5V)
82pF
1k
Q1
Si9433DY
OR MMSF4P01
MAX473
+2.9V OUTPUT
AT 2A
20pF
100k, 1%
1.5k
16k, 1%
10μF
10μF
SANYO OS-CON
Figure 14. 2.9V Low-Dropout Linear Regulator with Fast Transient Response
0.033Ω
V
IN
2.5V TO 5.25V
L1
5μH
CSH
CSL
C1
100μF
+5V AT 1A
DL
REF
D1
Q1
DH
LX
0.33μF
GND
SKIP
MAX797
PGND
C2
C3
100μF 100μF
V+
SHDN
FB
BST
0.1μF
100k
4.7μF
VL
SYNC
100k
L1 = SUMIDA CDRH125, 5μH
D1 = MOTOROLA MBR130
C1 - C3 = AVX TPS 100μF, 10V
33k
1N4148
2N7002
Q1 = SILICONIX Si9936 (BOTH SECTIONS)
OR MOTOROLA MMDF3N03L
0.01μF
1N4148
+3.3V
(EXTERNAL)
OPTIONAL SYNC AND LOW-VOLTAGE
START-UP CIRCUIT
190kHz - 340kHz
Figure 15. Low-Noise Boost Converter for Cellular Phones
______________________________________________________________________________________ 27
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
