MAX1553/MAX1554

High-Efficiency, 40V Step-Up

Converters for 2 to 10 White LEDs

Maxim Integrated | 7

www.maximintegrated.com

MAX1553

MAX1554

ENABLE

CONTROL

CIRCUITRY

CONTROL

LOGIC

EN

LX

DRIVER

GND

OV

COMPARATOR

REF

OV

UVLO

1.25V

BANDGAP

REFERENCE

BIAS

GENERATOR

CURRENT

LIMIT

REF

67k

Ω

128k

Ω

96k

Ω

110k

Ω

FB

BRT

SS

1.25V

MINIMUM

MINIMUM

ERROR

COMPARATOR

LX

SS

R1

10

Ω

R3

10k

Ω

R2

200k

Ω

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

LX

SS

R1

10

Ω

R3

10k

Ω

R2

330k

Ω

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 1. Circuit with the MAX1553 Driving Six White LEDs

Figure 2. Circuit with the MAX1553 Driving Nine White LEDs at

Up to 15mA

Functional Diagram