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LM3433 LED Driver


LM3433 – PowerWise® Common Anode Capable High-Brightness LED Driver with High-Frequency Dimming at Digi-Key


National Semiconductor's LM3433 is an adaptive constant-on-time DC/DC buck constant current controller. It 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 efficiency. 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 provided for LED brightness control. 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 pulse width modulation (PWM) control of LED current. The PWM functions by shorting out the LED with a parallel switch allowing high PWM dimming frequencies. Additional features include thermal shutdown, VCC under-voltage lockout, and logic level shutdown mode. LM3433 LED Driver

Features Applications
  •  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 efficiency
  •  Two control inputs are used to modulate LED brightness
  •  No output capacitor required
  •  Up to 1MHz switching frequency
  •  Low IQ, 1mA typical
  •  Soft start
  •  Adaptive programmable ON time allows for constant ripple current
  •  LLP-24 package
  •  LCD backlighting
  •  Projection systems
  •  Solid state lighting
  •  Automotive lighting

National Semiconductor Part Number Digi-Key Part Number Packaging  
LM3433SQ/NOPB LM3433SQTR-ND Tape/Reel Datasheet
LM3433SQCT-ND Cut Tape
LM3433SQDKR-ND Digi-Reel®

National Semiconductor Part Number Digi-Key Part Number Description  
LM3433SQ-36AEV/NOPB LM3433SQ-36AEV-ND Evaluation Kit LM3433 Eval Board Datasheet

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