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LT3909HDD#PBF

Description
IC LED DRIVER
CategoryAnalog mixed-signal IC    Drivers and interfaces   
File Size1MB,24 Pages
ManufacturerLinear ( ADI )
Websitehttp://www.analog.com/cn/index.html
Environmental Compliance
Download Datasheet Parametric View All

LT3909HDD#PBF Overview

IC LED DRIVER

LT3909HDD#PBF Parametric

Parameter NameAttribute value
Brand NameLinear Technology
Is it Rohs certified?conform to
MakerLinear ( ADI )
Parts packaging codeDFN
Contacts12
Manufacturer packaging codeDD
Reach Compliance Codecompliant
FEATURES
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LT3909
2-String × 60mA,
2MHz Step-Up LED Driver
with ±2% Current Matching
DESCRIPTION
The
LT
®
3909
is a 2-string × 60mA LED driver with a fixed
2MHz step-up DC/DC converter capable of driving up to 36V
of LEDs. Each LED string contains an accurate high-side
current source with ±2% current matching. Output volt-
age adapts to variations in LED V
F
for optimum efficiency.
Maximum LED current can be programmed from 10mA
to 60mA per string using a single resistor. LED brightness
can be reduced with analog dimming (up to 10:1) or with
PWM dimming (up to 40,000:1 at 100Hz, up to 160:1 at
25kHz) (independent of leakage at V
OUT
). The LED pins
can be paralleled for higher LED current.
Additional features include: programmable maximum V
OUT
for open LED protection, a fault flag to indicate open-LED
or LED-short-to-GND and an internal regulation loop to
safely limit junction temperature. The LT3909 also includes
internal compensation, internal soft-start and micropower
shutdown. The LT3909 is available in the 12-pin (3mm ×
3mm) DFN and 12-pin MSOP packages.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
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Up to 36V of LEDs, 2-String × 60mA LED Driver
Wide Input Range: 2.9V to 40V
Up to 40,000:1 PWM Dimming (250ns LED On-Time)
(Independent of Leakage at V
OUT
)
±2% LED Current Matching (Typ ±0.3%)
Integrated Schottky Diode
Internal 400mΩ, 40V, 1A Switch
Single Resistor Sets LED Current (10mA to 60mA)
for Both High-Side Current Sources
Output Adapts to LED V
F
for Optimum Efficiency
LED Current Regulated Even for V
IN
> V
OUT
Fault Flag + Protection for Open-LED and LED-Short-
to-GND (Other String Remains in Regulation)
Programmable Maximum V
OUT
(Regulated)
Internal Compensation, Soft-Start and Thermal
Regulation
Accurate EN/UVLO Threshold
Fixed 2MHz Switching Frequency
PDAs, Handheld Computers
GPS Receivers
Automotive Displays
High Contrast Instrument Clusters
APPLICATIONS
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TYPICAL APPLICATION
2-String × 40mA, 2MHz LED Driver for Ten White LEDs/String
V
IN
7V TO 36V
6.8µH
1µF
V
IN
402k
EN/UVLO
130k
PWM
CTRL
INTV
CC
LED1
LED2
FAULT
GND
I
SET
24.9k
SW
LT3909
V
OUT
FB
31.6k
2.2µF
LED Current Waveforms
20,000:1 PWM Dimming (100Hz)
V
IN
= 12V
I(LED1)
20mA/DIV
976k
100k
V
IN
10 LEDs
PER STRING
I(LED2)
20mA/DIV
PWM
2V/DIV
400ns/DIV
3909 TA01b
1µF
3909 TA01a
3909fb
For more information
www.linear.com/LT3909
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