Rainbow Electronics MAX1554 - Manual (Page 7)

MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
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MAX1553
MAX1554
ENABLE
CONTROL
CIRCUITRY
CONTROL
LOGIC
EN
V CC LX
DRIVER
GND
OV
COMPARATOR
REF
OV
UVLO
1.25V
BANDGAP
REFERENCE
BIAS
GENERATOR
CURRENT
LIMIT
V LIM REF
67k Ω
BRT
FB
SS
1.72V 128k Ω
206k Ω
MINIMUM
t OFF ONE-SHOT
MINIMUM
t ON ONE-SHOT
ERROR
COMPARATOR
LX
SS
R1
10
Ω
R3
10k
Ω
R2
200k
Ω V CC
FB
ON
OFF
BRT
GND
2.7V TO 5.5V
INPUT
C1
4.7 µF
C3
0.1 µF
C2
0.47 µF
25V
L1
47 µH
TOKO A920CY-470M
D1
CMDSH2-3
OV EN
D2–D7
WHITE
LEDs
PWM
OR
DC CONTROL
MAX1553
C4
4700pF
Figure 1. Circuit with the MAX1553 Driving Six White LEDs
LX
SS
R1
10
Ω
R3
10k
Ω
R2
330k
Ω V CC
FB
ON
OFF
BRT
GND
2.7V TO 5.5V
INPUT
C1
10 µF
C3
0.1 µF
C2
0.47 µF
50V
L1
4.7 µH
MURATA LQH32C
D1
CMDSH1-60M
OV EN
D2–D10
WHITE
LEDs
PWM
OR
DC CONTROL
MAX1553
C4
3300pF
Figure 2. Circuit with the MAX1553 Driving Nine White LEDs at
Up to 15mA
Functional Diagram