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LM3450 Datasheet Preview

LM3450 Datasheet

LED Drivers

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LM3450
www.ti.com
SNVS681D – NOVEMBER 2010 – REVISED MAY 2013
LED Drivers with Active Power Factor Correction and Phase Dimming Decoder
Check for Samples: LM3450
FEATURES
1
2 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
APPLICATIONS
• Dimmable Downlights, Troffers, and Lowbays
• Large Form Factor Bulbs
• Indoor and Outdoor Area SSL
• Power Supply PFC
DESCRIPTION
The LM3450/50A is a power factor controller (PFC)
with separate phase dimming decoder. The PFC
regulates the output voltage while maintaining
excellent 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 and
variable sampling rate provide smooth uniform
dimming. A dynamic hold circuit ensures that the
phase dimmer angle is decoded properly while
minimizing 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 it
continuously operates in the LM3450A. This
difference between the two devices defines the
suitable applications for each. The following is a
general 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
Typical Application
RETURN
EMI FILTER
AC
INPUT
VREF
VADJ
FLT2
BIAS
HOLD
ZCD
PWM
FLT1
VCC
LM3450/50A
DIM GATE
VAC
COMP
CS
GND
FB ISEN
SECONDARY
LED DRIVER
OPTICAL
ISOLATION
LED
LOAD
HOLD
RETURN
PWM
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
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 © 2010–2013, Texas Instruments Incorporated




etcTI

LM3450 Datasheet Preview

LM3450 Datasheet

LED Drivers

No Preview Available !

LM3450
SNVS681D – NOVEMBER 2010 – REVISED MAY 2013
Connection Diagram
Top View
1 VREF
2 VADJ
3 FLT2
4 FLT1
5 DIM
6 VAC
7 COMP
8 FB
BIAS
HOLD
ZCD
VCC
GATE
CS
GND
ISEN
16
15
14
13
12
11
10
9
Figure 1. 16-Lead TSSOP
Package Number PW
www.ti.com
PIN DESCRIPTIONS
Pin Name
Description
Application Information
1 VREF
3V Reference
Reference Output: Connect directly to VADJ or to resistor divider feeding VADJ
and to necessary external circuits.
2 VADJ
Analog Adjust
Analog Dim and Phase Dimming Range Input: Connect directly to VREF to force
standard 70% phase dimming range. Connect to resistor divider from VREF to
extend usable range of some phase dimmers or for analog dimming. Connect to
GND for low power mode.
3 FLT2
Filter 2
Ramp Comparator Input: Connect a series resistor from FLT1 capacitor and a
capacitor to GND to establish second filter pole.
4 FLT1
Filter 1
Angle Decoder Output: Connect a series resistor to a capacitor to GND to
establish first filter pole.
5
DIM
500 Hz PWM Output
Open Drain PWM Dim Output: Connect to dimming input of output stage LED
driver (directly or with isolation) to provide decoded dimming command.
6
VAC
Sampled Rectified Line
Multiplier and Angle Decoder Input: Connect to resistor divider from rectified AC
line.
7 COMP
Compensation
Error Amplifier Output and PWM Comparator Input: Connect a capacitor to GND
to set the compensation.
8 FB
Feedback
Error Amplifier Inverting Input: Connect to output voltage via resistor divider to
control PFC voltage loop for non-isolated designs. Connect a 5.11kresistor to
GND for isolated designs (bypasses error amplifier). Also includes over-voltage
protection and shutdown modes.
Input Current Sense Non-Inverting Input: Connect to diode bridge return and
9 ISEN Input Current Sense resistor to GND to sense input current for dynamic hold. Connect a 0.1µF
capacitor and Schottky diode to GND, and a 0.22µF capacitor to HOLD.
10 GND
Power Ground
System Ground
11 CS
Current Sense
MosFET Current Sense Input: Connect to positive terminal of sense resistor in
PFC MosFET source.
12 GATE
Gate Drive
Gate Drive Output: Connect to gate of main power MosFET for PFC.
13 VCC
Input Supply
Power Supply Input: Connect to primary bias supply. Connect a 0.1µF bypass
capacitor to ground.
14
ZCD
Zero Crossing Detector
Demagnetization Sense Input: Connect a 100kresistor to transformer/inductor
winding to detect when all energy has been transferred.
15 HOLD
Dynamic Hold
Open Drain Dynamic Hold Input: Connect to holding resistor which is connected
to source of passFET.
16
BIAS
Pre-regulator Gate Bias
Pre-regulator Gate Bias Output: Connect to gate of passFET and through
resistor to rectified AC (drain of passFET) to aid with startup.
2 Submit Documentation Feedback
Product Folder Links: LM3450
Copyright © 2010–2013, Texas Instruments Incorporated


Part Number LM3450
Description LED Drivers
Maker etcTI
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LM3450 Datasheet PDF






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