LX1745 データシートの表示（PDF） - Microsemi Corporation
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LX1745 Datasheet PDF : 16 Pages
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INTEGRATED PRODUCTS
LX1745
Triple Output Boost – LED Driver / LCD Bias
PRODUCTION DATASHEET
Name
IN
DRV
SRC
OVP
LFB
GND
BRT
REF
SWx
FBx
ADJx
LSHDN
SHDNx
CS
FUNCTIONAL PIN DESCRIPTION
Description
Unregulated IC Supply Voltage Input – Input range from +1.6V to 6.0V. Bypass with a 1µF or greater capacitor
for operation below 2.0V.
LED MOSFET Gate Driver – Connects to an external N-Channel MOSFET.
LED MOSFET Current Sense Input - Connects to the External N-Channel MOSFET Source.
Over Voltage Programming Pin – Connects to a resistor divider between the output load and GND to set the
maximum output voltage. OVP has a voltage threshold of 1.2V
LED Current Feedback Input – Connects to a current sense resistor between the LED output load and GND to
set the LED drive current.
Common terminal for ground reference.
LED Dimming Signal Input – Provides the internal reference, via an internal filter and gain resistor, allowing for a
dynamic output LED current adjustment that corresponds to the PWM input signal duty cycle. Either a PWM
signal or analog voltage can be used. The actual BRT pin voltage range is from VIN to GND. Minimize the
current sense resistor power dissipation by selecting a range for VBRT = 0.0V to 0.5V.
Buffered Reference Output – Connected to the internal bandgap reference voltage of 1.2V.
LCD Bias Inductor Switch Connection – Internally connected to the drain of a 28V N-channel MOSFET. SW is
high impedance in shutdown.
Feedback Input – Connect to a resistive divider network between the output and GND to set the output voltage
between VCC (IN) and 25V. The feedback threshold is 1.29V.
LCD Bias Adjustment PWM Signal Input – Connect to an RC filter allowing for dynamic output voltage
adjustment >±15%, corresponding to a varying duty cycle. Either a PWM signal or analog voltage can be used.
The ADJ input voltage range is from 0.9V to VIN DC. The ADJx pin should be connected to ground when the
internal reference is used.
LED Driver Active-Low Shutdown Input – A logic low shuts down the LED driver circuitry and reduces the supply
current by 60µA (Typ). Pull LSHDN high for normal operation.
LCD Bias Active-Low Shutdown Input – A logic low shuts down the LCD Bias circuitry and reduces the supply
current by 60µA (Typ). Pull SHDNx high for normal operation.
Current-Sense Amplifier Input – Connecting a resistor between CS and GND sets the peak inductor current
limit.
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
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