LX1992
L I N F I N I T Y
D I V I S I O N
High Efficiency LED Driver
P
RODUCTION
DESCRIPTION
KEY FEATURES
WWW .
Microsemi
.C
OM
The LX1992 is a compact high
efficiency step-up boost controller for
driving white or color LEDs in
backlight or frontlight systems and
offers designers maximum flexibility
with respect to efficiency and cost.
The LX1992 features a pseudo-
hysteretic pulse frequency modulation
topology and uses an external N-
Channel MOSFET.
Further, the
LX1992 features control circuitry that
is optimized for portable systems (e.g.,
quiescent supply current of 80碌A
(typ) and a shutdown current of less
than
1碌A).
These
design
enhancements provide for improved
performance in battery operated
systems applications.
The device input voltage range is
from 1.6V to 6.0, allowing for a wide
selection of system battery voltages
and
start-up
operation
is
guaranteed at 1.6V input.
Programming the output current is
readily achieved by using one external
current sense resistor in series with the
LEDs. In this configuration, LED
current provides a feedback signal to
the FB pin, maintaining constant current
regardless of varying LED forward
voltage (V
F
). Moreover, the LX1992 is
capable of achieving output currents in
excess of 150mA, depending on the
MOSFET selected.
The LX1992 has an additional feature
for simple dynamic adjustment of the
output current (i.e., up to 100% of the
maximum
programmed
current).
Designers can make this adjustment via
an analog reference signal or a direct
PWM generated signal applied to the
ADJ pin and any PWM amplitude is
easily accommodated with a single
external resistor.
The LX1992 is available in both the 8-
Pin MSOP, and the miniature 8-Pin MLP
requiring minimal PCB area.
> 90% Efficiency
80碌A Typical Quiescent Supply
Current
Externally Programmable Peak
Inductor Current Limit For
Maximum Efficiency
Logic Controlled Shutdown
< 1碌A Shutdown Current
Dynamic Output Current
Adjustment Via Analog
Reference Or Direct PWM Input
8-Pin MSOP Package or 8-Pin
MLP
APPLICATIONS/BENEFITS
Pagers
Wireless Phones
PDAs
Handheld Computers
General LCD Bias Applications
LED Driver
Digital Camera Displays
IMPORTANT:
For the most current data, consult
MICROSEMI鈥檚
website:
http://www.microsemi.com
PRODUCT HIGHLIGHT
L
1
V
BAT
= 1.6V to 6.0V
47
碌
H
1206 C ase Size
C
1
4.7
碌
F
DR V
IN
SR C
ON
O FF
SHD N
LX1992
FB
ADJ
GND
CS
R
CS
4
k
鈩?/div>
V
F
= 3.6V typ.
I
LED
= 20mA to 0mA
R
SET
15鈩?/div>
LX1992
LX1992
T
A
(掳C)
0 to 70
PACKAGE ORDER INFO
Plastic MLP
Plastic MSOP
LM
8-Pin
DU
8-Pin
LX1992CLM
LX1992CDU
Note: Available in Tape & Reel.
Append the letter 鈥淭鈥?to the part number. (i.e. LX1992CDUT)
Copyright
铮?/div>
2000
Rev. 1.1, 2002-11-21
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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