Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 11

Copyright

© 2000

Rev. 1.1b, 2005-03-03

LX1741

High Efficiency High Voltage Boost Controller

I N T E GRA T ED

PR ODUC T S

EVALUATI ON BOA RD ( C ONTI N UED)

VBAT

GND

VCC

SHDN

VADJ

VOUT

GND

C5

4.7µF

25V

C1

1000pF

50V

C4

4.7µF

25V

C2

0.1µF

50V

C3

2.2µF

16V

R7

10K

R8

4.02K

R3

619K

R4

100K

R2

49.9K

R1

698K

R5

1K

R6

1K

JB1

V

CC

JB2

REF

ADJ

JB4

VLIM

Q2

MMBT3904LT1

CR1

UPS5819

LX1741

Q1

FDV303N

VR1

24V

225mW

BZX84C24LT1

L1

47µH

X

X

Figure 8

– LX1741 Boost Evaluation Board Schematic

CHARACT ER I S TI C CURVES

Channel 1

Channel 2

Figure 9 –

Channel 2: Inductor Current (100mA/div.)

0

5

10

15

20

25

30

0.1 0.2 0.3

0.4 0.5 0.6

0.7 0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

Adj ustment Voltage

F

igure 10 –

•

0 ~ 0.6V : LX1741 uses internal 1.29V reference.

•

0.7V ~ 0.8V : transition from internal to external reference.

•

0.9 to 1.6V : LX1741 defaults to external voltage reference.