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ZCD

GATE

LM3450/50A

GND

COMP

HOLD

DIM

FLT2

FLT1

PWM

BIAS

RETURN

SECONDARY

LED DRIVER

OPTICAL

ISOLATION

RETURN

EMI FILTER

PWM

INPUT

LED

LOAD

SEN

REF

ADJ

HOLD

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

DESCRIPTION

The LM3450/50A is a power factor controller (PFC)

• Critical Conduction Mode PFC

with separate phase dimming decoder. The PFC

• Over-Voltage Protection

regulates the output voltage while maintaining

• Feedback Short Circuit Protection

excellent power factor. The phase dimming decoder

interprets the phase angle and remaps it to a 500Hz

• 70:1 PWM Decoded From Phase Dimmer

PWM output. This device is ideal for implementing a

• Analog Dimming

dimmable off-line LED driver for 10-100W loads.

• Programmable Dimming Range

The phase dimming decoder has several unique

• Digital Angle and Dimmer Detection

features. The input-output mapping is programmable

• Dynamic Holding Current

for design flexibility, while a dynamic filter and

variable sampling rate provide smooth uniform

• Smooth Dimming Transitions

dimming. A dynamic hold circuit ensures that the

• Low Power Operation

phase dimmer angle is decoded properly while

• Start-Up Pre-Regulator Bias

minimizing extra power loss.

• Precision Voltage Reference

The LM3450A is identical to the LM3450 with the

exception of one circuit operation. The dynamic hold

APPLICATIONS

current is sampled in the LM3450 while it

continuously operates in the LM3450A. This

• Dimmable Downlights, Troffers, and Lowbays

difference between the two devices defines the

• Large Form Factor Bulbs

suitable applications for each. The following is a

• Indoor and Outdoor Area SSL

general guideline for choosing the correct device:

• Power Supply PFC

• Any 120V designs with P

OUT

> 15W - LM3450A

• Any 230V designs with P

OUT

> 25W - LM3450A

• 120V 2-Stage designs with P

OUT

< 15W - LM3450

• 230V 2-Stage designs with P

OUT

< 25W - LM3450

Typical Application

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.

2All trademarks are the property of their respective owners.

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.

Summary of content (40 pages)

PAGE 1
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 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.
PAGE 2
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com Connection Diagram Top View 1 2 3 4 5 6 7 VREF BIAS VADJ HOLD FLT2 ZCD FLT1 VCC DIM GATE VAC CS COMP 8 FB GND 16 15 14 13 12 11 10 ISEN 9 Figure 1. 16-Lead TSSOP Package Number PW PIN DESCRIPTIONS Pin 2 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.
PAGE 3
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. ABSOLUTE MAXIMUM RATINGS (1) (2) VCC, HOLD, DIM, BIAS -0.3V to 25.0V HOLD Power 250 mW Continuous BIAS Current 5.0mA Continuous ZCD Current +/- 10mA COMP, FB, VAC, FLT1, FLT2, VREF, CS, VADJ -0.3V to 7.0V ISEN -7.0V to 7.
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LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com ELECTRICAL CHARACTERISTICS (1) Unless otherwise specified VCC = 14V. Specifications in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature Range ( TJ = −40°C to +125°C). Typical values represent the most likely parametric norm at TA = TJ = +25°C, and are provided for reference purposes only.
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LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 ELECTRICAL CHARACTERISTICS(1) (continued) Unless otherwise specified VCC = 14V. Specifications in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature Range ( TJ = −40°C to +125°C). Typical values represent the most likely parametric norm at TA = TJ = +25°C, and are provided for reference purposes only.
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LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS TA=+25°C and VCC = 14V unless otherwise specified Leading Edge Blanking vs. Junction Temperature 150 36 146 32 142 tLEB (ns) RDS-ON ( ) HOLD RDSON vs. Junction Temperature 40 28 24 20 -50 138 134 -14 22 58 94 130 -50 130 -14 94 130 TEMPERATURE (°C) Figure 2. Figure 3. Current Limit Threshold vs. Junction Temperature VAC = 3V; VCMP = VTHM + 1.5V Multiplier Gain vs.
PAGE 7
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) TA=+25°C and VCC = 14V unless otherwise specified VCC UVLO Threshold vs. Junction Temperature Shutdown Current vs. Junction Temperature 14 580 13 560 11 540 IQ (#A) VCC (V) UVLO Rising 10 UVLO Falling 8 7 -50 -14 22 58 520 500 94 480 -50 130 -14 TEMPERATURE (°C) 22 FB Reference vs. Junction Temperature 2.510 3.02 2.506 3.01 2.502 VFB (V) VREF (V) VREF Reference vs.
PAGE 8
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) TA=+25°C and VCC = 14V unless otherwise specified Transconductance vs. VFB Current Sense Threshold vs. VCOMP and VAC 250 4.90 200 3.92 150 2.94 VCS (V) GM (Ps) VAC = 4V 100 1.96 50 0.98 VAC = 3V VAC = 2V VAC = 1V VAC = 0.5V VAC = 0.1V 0 1.5 2.0 2.5 3.0 0.00 1.0 3.5 1.8 2.6 3.4 VFB (V) VCMP (V) Figure 14. Figure 15. 4.2 5.0 Decoder Mapping from VAC to DIM 1.
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LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 BLOCK DIAGRAM *LM3450 and LM3450A are identical except where indicated in blue DIM FLT2 VCCUV + - FLT1 VCCUV 500 Hz Triangle 1 PA VADJ 75 mV + - + - 3V Low Power VREF Amplitude Adjust + - HOLD 5 PA SAMPLE and LOG REMAP VAC 500 k: DOUT ISEN 40 k: LM3450A has Continuous Hold Multiplier 1.4V + - Burst LEB + - R GND Sampled Hold DIN 2R + - Transition ANGLE DIN DOUT DEMOD COMP PRE-BIAS COMP PWM 50 PA 2.7V FB 2.
PAGE 10
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com RBS CPFC VREF CREF RETURN DSW BIAS QPS RAD2 + COUT RHLD VADJ HOLD FLT2 ZCD FLT1 VCC FLYBACK OUTPUT - RAD1 RZCD RF2 CF2 AC INPUT CF1 RF1 CVCC LM3450/50A PWM TO OPTO DIM GATE VAC CS 24V QSW RAC2 RCS RAC1 COMP FEEDBACK FROM OPTO GND CHLD CCMP FB CSEN RSEN ISEN RFB1 RETURN Figure 17.
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LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 For higher power applications, where the dynamic hold provides much less current on average, the LM3450A can be used. The LM3450A has continuous dynamic hold which prevents the dimmer from ever misfiring. This is extremely helpful when designing for single stage solutions, where there is no second stage to provide good line rejection.
PAGE 12
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com The output voltage has to be regulated slowly to ensure the converter ignores the twice line frequency ripple present on the output. Therefore, the voltage loop containing the error amplifier should have a bandwidth at least an order of magnitude slower (<20Hz is common). Sometimes the bandwidth is increased to improve transient response, which is the case with off-line dimmable LED drivers.
PAGE 13
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 i IS-PK IP-PK IIN-PK tON t TSW Figure 20. CRM Flyback Current Waveforms Rectified AC L LM3450/50A VAC RAC2 + 1/3 COMP 50 P$ 5V 2.5V OPTO (Isolated) VOUT (Nonisolated) 5 k: + - 2.7V FB RFB2 QSW LOGIC CCMP RFB1 1.5V GATE Multiplier RAC1 ZCD RZCD CS + RCS Error Amp Disable 346mV + - 168mV + - Shutdown + - OVP 3V GND Figure 21.
PAGE 14
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com POWER FACTOR CONTROLLER The LM3450/50A uses CRM control to regulate the output voltage and provide power factor correction. In a nonisolated boost topology, an external voltage divider (RFB1, RFB2) is used to sense the output voltage, as shown in Figure 21. The divider is connected to the inverting input (FB) of the internal error amplifier. The LM3450/50A regulates the feedback voltage (VFB) to 2.5V in a closed loop fashion.
PAGE 15
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 VSW VRING VR VIN t VZCD 1.3V t Figure 22. ZCD Waveforms for Flyback Design ZERO CURRENT DETECTION ZCD is implemented with a 100kΩ resistor from the ZCD pin to a coupled winding on the transformer or inductor as shown in Figure 21. This winding is also used to bootstrap VCC after start-up. When QSW turns off, the voltage at the ZCD pin (VZCD) increases as energy is transferred through the auxiliary winding.
PAGE 16
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com If the COMP pin voltage (VCMP) falls below 1.4V at any time, the device enters burst mode where the GATE is off for 340µs then is turned on. If VCMP is still below 1.4V at the end of the on-time then another 340µs off-time occurs. However, if VCMP has risen above 1.4V, the converter continues switching until it falls below the threshold again.
PAGE 17
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 LOW POWER SHUTDOWN The LM3450/50A can be placed into a low power shutdown by grounding the VADJ pin (any voltage below 75mV). During low power shutdown, the device will turn on the GATE for one cycle followed by a fixed off-time of 42µs and the cycle repeats. During shutdown, the DIM output will be high (zero light output) since the buffer rail at FLT1 will be at or near zero.
PAGE 18
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com PHASE DIMMER OPERATION A simplified schematic of a phase dimmer is shown in Figure 25. An RC network consisting of R1, R2, and C1 delay the turn-on of the triac until the voltage on C1 reaches the trigger voltage of the diac. Increasing the resistance of the potentiometer (wiper moving downward) increases the turn-on delay which decreases the ontime or “conduction angle” of the triac (θ). This reduces the average power delivered to the load.
PAGE 19
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 VCC Rectified AC RAC2 0-3V Analog Input RAC1 VSB RPB OPTO PWM OUT VREF VADJ VAC ANGLE DEMOD DIM 500 Hz RSB + 3V REF FLT2 DIN 500k SAMPLE / REMAP DOUT DOUT FLT1 RF1 RF2 CF1 Transition CF2 DIN LM3450/50A Figure 26. Dimming Decoder Circuit PHASE DIMMING DECODER The LM3450/50A uses the rectified AC line voltage to interpret the conduction angle.
PAGE 20
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com VADJ VFLT2 VFLT1 Figure 28. FLT1 to FLT2 Mapping The FLT1 signal is routed through a 2 pole low pass filter (RF1, CF1, RF2, CF2), as shown in Figure 26, to remove the twice line frequency ripple. The resulting analog signal at FLT2 is compared to a 500Hz Triangle wave to create the inverted PWM signal at the DIM pin as shown in Figure 29: VFLT2 VDIM Figure 29.
PAGE 21
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 DIM PIN DUTY CYCLE (INVERTED) 1.2 VADJ=3V 1.0 2.5V 2V 0.8 0.6 1.5V 0.4 1V 0.2 0.5V 0.0 0.0 0.2 0.4 0.6 0.8 1.0 LM3450/A DEMODULATED VAC PIN DUTY CYCLE Figure 30. Complete Decoder Mapping Since the buffered decoder output has amplitude equal to VADJ and the resulting PWM signal is filtered into an analog voltage at FLT2, the VADJ pin can be used to change the mapping as shown in Figure 30.
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LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com DYNAMIC HOLD A forward phase “triac” dimmer requires a minimum amount of current to be flowing through it during the entire conduction angle. This is referred to as hold current. If the minimum hold current requirement is not met, the triac will shut off (misfire). During normal operation, the converter will demand some amount of input current. However, at any point during the cycle, the input current can be low enough to cause a misfire.
PAGE 23
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 The dynamic hold function is also necessary for reverse phase dimmers, but for a different reason. Reverse phase dimmers do not use triacs, therefore they do not require a minimum “holding” current. Instead, they need what is commonly called bleeder current. When a reverse phase dimmer turns off, the AC voltage is at a high value.
PAGE 24
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com THERMAL PROTECTION With the LM3450A, QPS has to dissipate more power than with the LM3450. During worst case conditions such as open LED load, the converter will be demanding very little current regardless of the triac position. If the phase dimmer conduction angle is large and the load is not present, QPS has to dissipate many watts since the dynamic hold is attempting to regulate the current to ten's of mA.
PAGE 25
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 Figure 35 shows how the LM3450/50A provides a quick way to generate the necessary primary bias supply at start-up. Since the AC line peak voltage is always higher than the rating of the controller, all designs require an N-channel MosFET (passFET). The passFET (QPS) is connected with its drain attached to the rectified AC. The gate of QPS is connected to the BIAS pin which has a stack of 2 Zener diodes internal to the device.
PAGE 26
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com DESIGN INFORMATION HOW TO SELECT THE CORRECT DEVICE (LM3450 or LM3450A) What application(s) are suitable for the LM3450, and when is the LM3450A appropriate? The difference centers on the power dissipation in the passFET. The passFET stands off the high AC voltage from the LM3450/50A, and provides a path for the hold current.
PAGE 27
LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 Applications Information See AN-2098 (literature number SNVA463) and/or AN-2150 (literature number SNVA485) for detailed design and application information.
PAGE 28
LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com 15W TWO STAGE DESIGN SPECIFICATIONS AC Input Voltage: 120VAC nominal (90VAC - 135VAC) or 230VAC nominal (180VAC - 265VAC) Regulated Flyback Output Voltage: 50V Regulated LED Current: 350mA LED Stack Voltage Maximum: 45V Table 2.
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LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 Table 2. Bill of Materials(1) (continued) Reference Designator Description Manufacturer Part Number L4 IND SHIELD 470µH 1.06A SMT COILCRAFT MSS1278-474KLB Q1 MOSFET N-CH 800V 3A DPAK ST MICRO STD4NK80ZT4 120V MOSFET N-CH 600V 4.4A DPAK INFINEON IPD60R950C6 230V MOSFET N-CH 800V 3A DPAK ST MICRO STD4NK80ZT4 Q3, Q4 TRANS NPN 40V 0.6A SOT-23 FAIRCHILD MMBT4401 Q5 MOSFET P-CH 70V 5.
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LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com SINGLE STAGE LED DRIVER – LM3450A FLYBACK SOFTSTART VADJ L1 R27 EMI FILTER R7 AC MAINS Q6 VREF C3 R1 D17 L2 R28 C5 R2 D10 C2 + D4 D18 VCC - BIAS COMP RETURN C1 L3 C6 C4 R10 R3 D1 D6 VREF BIAS VADJ HOLD Q1 C10 R6 R4 D7 Thermal Protect C11 D2 R5 R8 FLT2 ZCD VOUT T1 C7 AUX AUX C12 D5 D3 R9 C8 VCC FLT1 C13 PWM D8 C9 LM3450A Q2 DIM GATE VAC CS R11 R26 C14 D9 C15 1.
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LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 30W SINGLE STAGE DESIGN SPECIFICATIONS AC Input Voltage: 120VAC nominal (90VAC - 135VAC) or 230VAC nominal (180VAC - 265VAC) Flyback Output Voltage Maximum: 60V Regulated LED Current: 700mA Table 3. Bill of Materials (1) Reference Designator Description Manufacturer Part Number LM3450A IC PFC CONT 16-TSSOP TI LM3450AMT LMV431 IC SHUNT REG SOT-23 TI LMV431AIM5 U1 IC DUAL OP-AMP TI LM2904 120V CAP CER 0.
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LM3450 SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 www.ti.com Table 3. Bill of Materials(1) (continued) Reference Designator Description Manufacturer Part Number R1 120V RES 330Ω 5% 1W 2512 VISHAY CRCW2512330RJNEG 230V RES 510Ω 5% 1W 2512 VISHAY CRCW2512510RJNEG 120V RES 430Ω 5% 1W 2512 VISHAY CRCW2512430RJNEG 230V RES 1.6kΩ 5% 1W 2512 VISHAY CRCW25121K60JNEG 120V RES 402kΩ 1% 0.25W 1206 VISHAY CRCW1206402KFKEA 230V RES 953kΩ 1% 0.
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LM3450 www.ti.com SNVS681D – NOVEMBER 2010 – REVISED MAY 2013 REVISION HISTORY Changes from Revision C (May 2013) to Revision D • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 5-Feb-2014 Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Mar-2014 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM3450AMTX/NOPB TSSOP PW 16 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.0 Q1 LM3450AMTX/NOPB TSSOP PW 16 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.0 Q1 LM3450MTX/NOPB TSSOP PW 16 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Mar-2014 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3450AMTX/NOPB TSSOP PW 16 2500 367.0 367.0 35.0 LM3450AMTX/NOPB TSSOP PW 16 2500 367.0 367.0 35.0 LM3450MTX/NOPB TSSOP PW 16 2500 367.0 367.0 35.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.