Rainbow Electronics MAX799 - Manual (Page 28)

MAX796/MAX797/MAX799
Step-Down Controllers with
Synchronous Rectifier for CPU Power
28 ______________________________________________________________________________________
MAX797
CSL CSH
SS
VL
SYNC
REF
GND
V+
Q1
FB
191k
49.9k
+12V AT 2A
BST
DH
LX
PGND
SKIP
SHDN
VIN
4.75V TO 6V
C2
150 µ F
C3
150 µ F
0.33 µ F
0.01 Ω
0.01 µ F
C1
220 µ F
D1
4.7 µ F
L1
5 µ H
L1 = 2x SUMIDA CDRH125-100 IN PARALLEL
D1 = MOTOROLA MBR640
Q1 = MOTOROLA MTD20N03HDL
C1 = SANYO OS-CON 220
µ F, 10V
C2, C3 = SANYO OS-CON 150 µ F, 16V
Figure 16. 5V-to-12V PWM Boost Converter
MAX797
CSL CSH
VL
SYNC REF GND
V+
Q1
T1
Q2
FB
200k
200k
OUTPUT
+5V AT 500mA
BST
CMPSH-3A
DH
LX
DL
PGND
SKIP
HI EFF
LOW IQ
SHDN
INPUT
3V TO 6.5V
4.7 µ F
0.33 µ F
33m Ω
220 µ F 220 µ F
100 µ F
Q1, Q2 = Si9410DY
T1 = COILTRONIX CTX 10-4
10
µ H PRIMARY, 1:1
START-UP SUPPLY VOLTAGE = 3.5V TYP
Figure 17. 90% Efficient, Low-Voltage PWM Flyback Converter (4 Cells to 5V)
____________________________________________Application Circuits (continued)