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PDF LX1745 Data sheet ( Hoja de datos )
| Número de pieza | LX1745 | |
| Descripción | Triple Output Boost - LED Driver / LCD Bias | |
| Fabricantes | Microsemi Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LX1745 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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INTEGRATED PRODUCTS
LX1745
Triple Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
DESCRIPTION
The LX1745 is a compact high guaranteed at a VIN equal to 1.6V with
efficiency step-up boost regulator for sustained operation as 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 voltages with an current sense resistor in series with the
additional two integrated boost converters. 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 LX1745 minimizes system cost Depending on the MOSFET selected, the
and condenses layout area making it ideal LX1745 is capable of achieving an LED
for PDA, smart-phone, and digital camera drive in excess of 1.0W.
applications.
The LX1745 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 for LCD Bias generation, the Bias output voltages (up to ±15% typ)
LED driver utilizes an external N-Channel through separate IC interfaces. Each
MOSFET in order to maintain maximum interface has an internal RC filter allowing
efficiency along with flexible power designers to make these adjustments via a
requirements..
direct PWM input signal or an analog
The LX1745’s control circuitry is reference signal. Further, any PWM
optimized for portable systems with a amplitude is easily accommodated using a
shutdown current of less than 1µA. The single external resistor.
input voltage range of 1.6V to 6.0 allows The LX1745 is available in the low-
for a wide selection of system battery profile 20-Pin TSSOP.
voltages and start-up is
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
LX1745
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 Two LCD Bias Voltage
Adjustments Via Analog
Reference Or Direct PWM
Input
20-Pin TSSOP Package
APPLICATIONS
Pagers
Smart Phones
PDAs
Handheld Computers
General LCD Bias Applications
LED Driver
LX1745 Evaluation Board
Copyright 2000
Rev. 1.1a, 2004-02-06
PACKAGE ORDER INFO
TA (°C)
-40 to 85
Plastic TSSOP
PW 20-Pin
LX1745-CPW
Note: Available in Tape & Reel.
Append the letter “T” to the part number.
(i.e. LX1745-CPWT)
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
1 page  
INTEGRATED PRODUCTS
LX1745
Triple Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
SIMPLIFIED BLOCK DIAGRAM
LFB
BRT
Reference
Logic
50pF 2.5MΩ
IN
OVP
REF
Control
Logic
Driver
Current
Limit
Shutdown
Logic
Control
Logic
Driver
DRV
SRC
GND
4µA
CS
LSHDN
SHDNx
FBx
SWx
ADJx
Reference
Logic
50pF 2.5MΩ
Current
Limit
Voltage
Reference
ADJx
50pF
Reference
Logic
2.5MΩ
Control
Logic
Driver
Current
Limit
Figure 1 – Simplified Block Diagram
FBx
SWx
Copyright 2000
Rev. 1.1a, 2004-02-06
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
5 Page 
INTEGRATED PRODUCTS
LX1745
Triple Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
EVALUATION BOARD
Name
VIN
GND
ADJ1
ADJ2
SHDN
SHDN1
SHDN2
VLCD1
-VLCD
VLCD2
VOUT
FDBK
BRT
REF
Table 2: 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.
Apply a DC voltage or a PWM voltage to this pin to adjust the LCD2
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.
Pulled up to VIN on board (10KΩ), Ground to inhibit the VLCD2.
≤25V
Output voltage test point. Programmed for 18V output, adjustable up to
25V.
≥-25V
Output voltage mirror of VLCD1
≤25V
Output voltage test point. Programmed for 22V output, adjustable up to
25V.
≤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.
1.19V Typ. Buffered IC reference output.
Note: All pins are referenced to ground.
Copyright 2000
Rev. 1.1a, 2004-02-06
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 LX1745.PDF ] | |
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