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1
Introduction
The LM3450A evaluation board is designed to provide an AC to LED solution for a 30W LED load.
Specifically, it takes an AC mains input and converts it to a constant current output of 700mA for a series
string of 1 to 13 LEDs (maximum LED stack voltage of 45V). There are two assembly versions designed
to operate from two different nominal AC input voltages, 120V
The board employs a two stage design with an LM3450A flyback primary stage and an LM3409HV
secondary stage. The LM3450A provides an isolated 50V regulated output voltage and a power factor
corrected input current. The LM3409HV uses the 50V flyback output as its input and provides a constant
current of 700mA to the LED load. This two stage design provides excellent line and load regulation as
well as isolation. The board is comprised of two copper layers with components on both sides and an FR4
dielelctric.
The two-stage design has several key advantages over a single stage design including:
No 120Hz LED current ripple
Better dimming performance at low dimming levels.
Better line disturbance rejection
Better efficiency using small LED stack voltages
2
Specifications
120V
30W Version
AC
Input Voltage Range: V
Regulated Flyback Output Voltage: V
Maximum LED Stack Voltage: V
Regulated LED Current: I
230V
30W Version
AC
Input Voltage Range: V
Regulated Flyback Output Voltage: V
Maximum LED Stack Voltage: V
Regulated LED Current: I
All trademarks are the property of their respective owners.
SNVA485B – June 2011 – Revised May 2013
Submit Documentation Feedback
AN-2150 LM3450A Evaluation Board
= 90V
– 135V
IN
AC
AC
= 50V
OUT
< 45V
LED
= 700mA
LED
= 180V
– 265V
IN
AC
AC
= 50V
OUT
< 45V
LED
= 700mA
LED
Copyright © 2011–2013, Texas Instruments Incorporated
SNVA485B – June 2011 – Revised May 2013
or 230V
. .
AC
AC
AN-2150 LM3450A Evaluation Board
User's Guide
1

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Summary of Contents for Texas Instruments AN-2150 LM3450A

  • Page 1 Maximum LED Stack Voltage: V < 45V • Regulated LED Current: I = 700mA All trademarks are the property of their respective owners. SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 2 EMI FILTER FLT2 FLT1 LM3409HV LM3450A LED Driver GATE LOAD INPUT OPTICAL ISOLATION COMP HOLD RETURN Figure 1. Schematic AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 3 Figure 4. 120V, 30W Version Figure 5. 230V, 30W Version Power Factor vs. Output Power Power Factor vs. Output Power SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 4 EN 61000-3 Class C Limits THD = 6.27% ; Fundamental = 316mA THD = 8.96% ; Fundamental = 167mA AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 5 Open Drain Dynamic Hold Input: Connect to holding HOLD Dynamic Hold resistor which is connected to source of passFET. SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 6 Connect to pin 5 (GND). Place 4-6 vias from DAP to Thermal PAD on bottom of IC bottom layer GND plane. AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 7 LMV431 IADJ LM3409HV POP2 DIMMING COFF OPTO2 PGATE POP2 SECONDARY LOAD LED DRIVER Figure 10. Simplified Evaluation Board Schematic SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 8 Since the input current has the same shape and phase as the input voltage, high power factor (PF) can easily be achieved. AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 9 • Switching Frequency at Nominal Input = 100kHz • Inductor/LED Current Ripple = 115mA CRM Flyback Converter Operating Points SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 10 RMS current, and dissipate the maximum power: The peak current limit should be at least 25% higher than the maximum peak input current: AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 11 – Maximum Diode Average Current D-MAX – Maximum Diode Peak Current D-PK-MAX – Maximum Diode Power Dissipation D-MAX Transformer Primary Inductance SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 12 Note that there are core materials that can tolerate higher flux densities; however, they are usually more expensive and not always practical for these designs. AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 13 – Transformer Core Figure of Merit Rectified AC BIAS POP2 UVLO CCUV LM3450A Figure 13. Bias Circuitry Bias Supplies and Capacitances Bias Supplies SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 14 The minimum primary bias supply capacitance is calculated, given a minimum V ripple specification, to keep V above UVLO at the worst-case current: (18) AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 15 – Twice Line Frequency Rectified AC BIAS HOLD 5 P$ 40 k: LM3450A Figure 14. Dynamic Hold Circuit with Thermal Protection SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 16 230V AC 120V AC REGULATED MIN INPUT CURRENT (mA) Figure 15. Output Power Restrictions (without thermal protection) AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 17 /x where x is a value between 4 and 7. R26+R29 should be chosen to be between 1MΩ and 2MΩ to IN-PK limit power dissipation. (23) SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 18 LM3409HV EN pin should be high. Definitions – Rectified AC Angle Detect Voltage – FLT1 frequency FLT1 – FLT2 frequency FLT2 AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 19 COMP to GND. The resistor divided flyback output voltage is regulated to the 1.24V LMV431 internal reference. Note the additional soft-start circuit using C34, D13, and D14. SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 20 (directly proportional). The output pole of the converter on the other hand follows these basic relationships: AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 21 (s) – Compensator Transfer Function COMP – Feedback Gain ω – Converter Output Pole ω – Compensator Secondary Integrator Pole SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 22 PCB layout iterations are frequently necessary as well. Consult available literature and/or an EMI specialist for help with this. It can be a daunting task. AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 23 The TVS diode (D1) voltage is set to prevent the MosFET from exceeding its maximum rating: SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 24 Many components are identical between both boards for simplicity, therefore some components on the 120V board are over-sized. 10.1 Specifications – 60Hz AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 25 Maximum drain-to-source voltage: (39) Maximum peak MosFET current: (40) Maximum RMS MosFET current: (41) Maximum power dissipation: (42) Resulting component choice: SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 26 Voltage rating: (53) Resulting component choice: (54) 10.7 Output Capacitance Minimum capacitance: (55) Voltage rating: (56) Resulting component choice: AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 27 Maximum flux density: (66) Resulting component choice: (67) 10.9 Transil Clamp TVS clamp voltage: (68) Resulting component choice: (69) SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 28 Converter DC gain: (78) LM3450A and external sensing DC gain: (79) Secondary compensator dominant pole: (80) Secondary compensator zero: (81) AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 29 Design Calculations - 120V, 30W www.ti.com Primary roll-off pole: (82) Resulting component choice: 30.1 (83) SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 30 Complete Evaluation Board Schematic www.ti.com Complete Evaluation Board Schematic Figure 25. Complete Evaluation Board Schematic AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 31 CRCW2512820RJNEG R5, R7 RES 200kΩ 1% 0.25W 1206 VISHAY CRCW1206200KFKEA R6, R11 RES 10Ω 1% 0.25W 1206 VISHAY CRCW120610R0FKEA SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 32 C29, C31, C40, Q20, R4, R13, R22, R27, R33, R40, R42, R49, R54, R59, R60, R63, R64, R75, R78, VR1 AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 33 R2, R3, R47 RES 820Ω 5% 1W 2512 VISHAY CRCW2512820RJNEG R5, R7 RES 475kΩ 1% 0.25W 1206 VISHAY CRCW1206475KFKEA SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 34 C29, C31, C40, Q20, R4, R13, R22, R27, R33, R40, R42, R49, R54, R59, R60, R63, R64, R75, R78, VR1 AN-2150 LM3450A Evaluation Board SNVA485B – June 2011 – Revised May 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 35: Pcb Layout

    PCB Layout www.ti.com PCB Layout Figure 26. Top Copper and Silkscreen Figure 27. Bottom Copper and Silkscreen SNVA485B – June 2011 – Revised May 2013 AN-2150 LM3450A Evaluation Board Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated...
  • Page 36: Important Notice

    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.