LM3433_14 Datasheet, PDF (1/15 Pages) Texas Instruments – Common Anode Capable High Brightness LED Driver with High Frequency Dimming

LM3433
www.ti.com
SNVS535B – OCTOBER 2007 – REVISED MARCH 2008
LM3433 Common Anode Capable High Brightness LED Driver with High Frequency
Dimming
Check for Samples: LM3433
FEATURES
1
•2 Operating input voltage range of -9V to -14V
w.r.t. LED anode
• Control inputs are referenced to the LED
anode
• Output current greater than 6A
• Greater than 30kHz PWM frequency capable
• Negative output voltage capability allows LED
anode to be tied directly to chassis for
maximum heat sink efficacy
• No output capacitor required
• Up to 1MHz switching frequency
• Low I_Q, 1mA typical
• Soft start
• Adaptive programmable ON time allows for
constant ripple current
• LLP-24 package
APPLICATIONS
• LCD backlighting
• Projection systems
• Solid state lighting
• Automotive lighting
DESCRIPTION
The LM3433 is an adaptive constant on-time DC/DC buck (step-down) constant current controller (a true current
source). The LM3433 provides a constant current for illuminating high power LEDs. The output configuration
allows the anodes of multiple LEDs to be tied directly to the ground referenced chassis for maximum heat sink
efficacy. The high frequency capable architecture allows the use of small external passive components and no
output capacitor while maintaining low LED ripple current. Two control inputs are used to modulate LED
brightness. An analog current control input is provided so the LM3433 can be adjusted to compensate for LED
manufacturing variations and/or color temperature correction. The other input is a logic level PWM control of LED
current. The PWM functions by shorting out the LED with a parallel switch allowing high PWM dimming
frequencies. High frequency PWM dimming allows digital color temperature control, interference blanking, field
sequential illumination, and brightness control. Additional features include thermal shutdown, V_CC under-voltage
lockout, and logic level shutdown mode. The LM3433 is available in a low profile LLP-24 package.
Typical Application Circuit
44.2k
0.1
PF
-12V
ADJ
EN
DIM
+3.3V
270 pF
4.7 PF
HO
T_ON
HS
ADJ
EN _{LM3433 BST}
DIM
V_CC
V_IN
LO
Q1
0.47 PF
Q2
2.2 PF
LED ANODE
Q3
LED
6 PH
0.01
22 PF
LED CATHODE
GND
0.01
PF
-12V
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007–2008, Texas Instruments Incorporated