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PDF LX1744 Data sheet ( Hoja de datos )
| Número de pieza | LX1744 | |
| Descripción | Dual Output Boost - LED Driver / LCD Bias | |
| Fabricantes | Microsemi Corporation | |
| Logotipo |  |
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INTEGRATED PRODUCTS
LX1744
Dual Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
DESCRIPTION
The LX1744 is a compact high equal to 1.6V with sustained operation as
efficiency step-up boost regulator for low as 1.1V.
driving white or color LEDs in LCD The maximum LED drive current is
lighting applications while supplying the easily programmed using one external
necessary LCD bias voltage with an current sense resistor in series with the
additional integrated boost converter.
LEDs. In this configuration, LED current
Designed for maximum efficiency and provides a feedback signal to the FB pin,
featuring a psuedo-hysteretic PFM maintaining constant current regardless of
topology (that decreases output voltage varying LED forward voltage (VF).
ripple), the LX1744 minimizes system cost Depending on the MOSFET selected, the
and condenses layout area making it ideal LX1744 is capable of achieving an LED
for PDA, smart-phone, and digital camera drive in excess of 1.0W.
applications.
The LX1744 provides simple dynamic
While the LCD Bias generation is adjustment of the LED drive current (0% to
implemented using an internal N-Channel 100% full range dimming) and the LCD
MOSFET, the LED driver utilizes an Bias output voltage (up to ±15% typ)
external N-Channel MOSFET in order to through separate IC interfaces. Each
maintain maximum efficiency along with interface has an internal RC filter allowing
flexible power requirements.
designers to make these adjustments via a
The LX1744’s control circuitry is direct PWM input signal or an analog
optimized for portable systems with a reference signal. Further, any PWM
shutdown current of less than 1µA. The amplitude is easily accommodated using a
input voltage range of 1.6V to 6.0V allows single external resistor.
for a wide selection of system battery The LX1744 is available in the 14-Pin
voltages and start-up is guaranteed at a VIN TSSOP, and the miniature 16-Pin MLP
requiring minimal PCB area.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
VBAT = 1.6V to 6.0V
- VLCD
VLCD1 = VIN to 25V
VLCD2 = VIN to 25V
PRODUCT HIGHLIGHT
L1
47µH
1206 Case Size
IN
SW1
DRV
SRC
OVP
LFB
FB1 CS
LX1744
SW2
REF
LSHDN
BRT
FB2 SHDN1
GND
ADJ1
SHDN2 ADJ2
ON OFF
ON OFF
ILED = 20mA to 0mA
C1
4.7µF
RSET
15Ω
ON OFF
KEY FEATURES
> 90% Maximum Efficiency
Low Quiescent Supply Current
Externally Programmable Peak
Inductor Current Limit for
Maximum Efficiency
Logic Controlled Shutdown
< 1µA Shutdown Current
Dynamic Output LED Current
and LCD Bias Voltage
Adjustment via Analog
Reference or Direct PWM Input
14-Pin TSSOP or 16-Pin MLPQ
Package
APPLICATIONS
Pagers
Smart Phones
PDAs
Handheld Computers
General LCD Bias Applications
LED Driver
LX1744 Evaluation Board
Copyright © 2000
Rev. 1.1b, 2005-03-01
TA (°C)
-40 to 85
PACKAGE ORDER INFO
Plastic TSSOP
PW 14-Pin
RoHS Compliant / Pb-free
Transition DC: 0442
Plastic MLP-Q
LQ 16-Pin
RoHS Compliant / Pb-free
Transition DC: 0430
LX1744CPW
LX1744CLQ
Note: Available in Tape & Reel.
Append the letters “TR” to the part number. (i.e. LX1744CLQ-TR)
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
1 page  
INTEGRATED PRODUCTS
LX1744
Dual Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
SIMPLIFIED BLOCK DIAGRAM
LFB
BRT
Reference
Logic
50pF 2.5MΩ
Control
Logic
Driver
DRV
SRC
GND
4µA
CS
IN
OVP
REF
ADJ
Reference
Logic
50pF 2.5MΩ
Shutdown
Logic
Control
Logic
Driver
4µA
LSHDN
SHDN
FB
SW
Figure – Simplified Block Diagram
Copyright © 2000
Rev. 1.1b, 2005-03-01
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
5 Page 
INTEGRATED PRODUCTS
LX1744
Dual Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
EVALUATION BOARD
Name
VIN
GNDx
ADJ
SHDN
SHDN
VLCD
-VLCD
VOUT
LFB
BRT
DRV
REF
Table 1: Input and Output Pin Assignments
Input/Output
Range
Description
0 to 6V
Main power supply for outputs.
0V Common ground reference.
0 to VIN-100mV
Apply a DC voltage or a PWM voltage to this pin to adjust the LCD1
output voltage. PWM inputs should be greater than 120Hz.
0 to VIN
Pulled up to VIN on board (10KΩ), Ground to inhibit the LED driver
output (VOUT).
Pulled up to VIN on board (10KΩ), Ground to inhibit the VLCD1.
≤25V
Output voltage test point. Programmed for 18V output, adjustable up to
25V.
≥-25V
Output voltage mirror of VLCD1
≤25V
LED drive voltage probe point.
0 to VIN
LED current sense feedback.
0 to 350mV
Apply a DC voltage or a PWM voltage to this pin to adjust the LED
current. PWM inputs should be greater than 120Hz with a DC portion
less than 350mV.
0 to VIN
LED Driver MOSFET Gate Driver Output
1.19V Typ. Buffered IC reference output.
Note: All pins are referenced to ground.
Copyright © 2000
Rev. 1.1b, 2005-03-01
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LX1744.PDF ] | |
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