Texas Instruments LM3450A

Description

The LM3450/50A is a power factor controller (PFC) with separate phase dimming decoder. The PFC regulates the output voltage while maintainingexcellent power factor. The phase dimming decoder interprets the phase angle and remaps it to a 500Hz PWM output. This device is ideal for implementing a dimmable off-line LED driver for 10-100W loads.The phase dimming decoder has several unique features. The input-output mapping is programmable for design flexibility, while a dynamic filter andvariable sampling rate provide smooth uniform dimming. A dynamic hold circuit ensures that the phase dimmer angle is decoded properly whileminimizing extra power loss.The LM3450A is identical to the LM3450 with the exception of one circuit operation. The dynamic hold current is sampled in the LM3450 while itcontinuously operates in the LM3450A. This difference between the two devices defines the suitable applications for each. The following is ageneral guideline for choosing the correct device:• Any 120V designs with POUT > 15W - LM3450A• Any 230V designs with POUT > 25W - LM3450A• 120V 2-Stage designs with POUT < 15W - LM3450• 230V 2-Stage designs with POUT < 25W - LM3450

Features

• Critical Conduction Mode PFC
• Over-Voltage Protection
• Feedback Short Circuit Protection
• 70:1 PWM Decoded From Phase Dimmer
• Analog Dimming
• Programmable Dimming Range
• Digital Angle and Dimmer Detection
• Dynamic Holding Current
• Smooth Dimming Transitions
• Low Power Operation
• Start-Up Pre-Regulator Bias
• Precision Voltage Reference

Remarks:1)L1 and L3 is used as input signals

2)L1 and L4 is used as input signals

Typical applications

• Dimmable Downlights
• Power Supply PFC
• Large Form Factor Bulbs

More information

• Datasheet
• IC product information