Texas Instruments Incorporated LM3445 Application Note
LM3445
Application Note 2069 LM3445 - 230VAC, 6W- 15W Isolated Flyback LED Driver
Literature Number: SNVA447B
LM3445 - 230VAC, 6W- 15W Isolated Flyback LED Driver AN-2069
LM3445 - 230VAC, 6W- 15W
Isolated Flyback LED Driver
Introduction
This demonstration board highlights the performance of a
LM3445 based Flyback LED driver solution that can be used
to power a single LED string consisting of 4 to 10 series connected LEDs from an 180 V
power supply. The key performance characteristics under
typical operating conditions are summarized in this application note.
This is a four-layer board using the bottom and top layer for
component placement. The demonstration board can be
modified to adjust the LED forward current, the number of series connected LEDs that are driven and the switching frequency. Refer to the LM3445 datasheet for detailed instructions.
A bill of materials is included that describes the parts used on
this demonstration board. A schematic and layout have also
been included along with measured performance characteristics.
Performance Specifications
to 265 V
RMS
, 50 Hz input
RMS
National Semiconductor
Application Note 2069
Montu Doshi
November 23, 2010
Key Features
•
Drop-in compatibility with TRIAC dimmers
•
Line injection circuitry enables PFC values greater than
0.94
•
Adjustable LED current and switching frequency
•
Flicker free operation
Applications
•
Retro-fit TRIAC Dimming
•
Solid State Lighting
•
Industrial and Commercial Lighting
•
Residential Lighting
Based on an LED Vf = 3.4V
Symbol Parameter Min Typ Max
V
IN
V
OUT
I
LED
P
OUT
f
sw
Input voltage 180 V
LED string voltage 13 V 20 V 27 V
LED string average current - 350 mA -
Output power - 7.2 W -
Switching frequency - 67 kHz -
Demo Board
30126904
RMS
230 V
RMS
Dimming Characteristics
265 V
RMS
30126924
© 2010 National Semiconductor Corporation 301269 www.national.com
LM3445 230VAC, 8W Isolated Flyback LED Driver Demo Board Schematic
AN-2069
Warning:
Warning:
Warning:
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The LM3445 evaluation board has exposed high voltage components that present a shock hazard. Caution must be taken when handling the evaluation
board. Avoid touching the evaluation board and removing any cables while the evaluation board is operating.
The ground connection on the evaluation board is NOT referenced to earth ground. If an oscilloscope ground lead is connected to the evaluation
board ground test point for analysis and the mains AC power is applied (without any isolation), the fuse (F1) will fail open. For bench evaluation, either
the input AC power source or the bench measurement equipment should be isolated from the earth ground connection. Isolating the evaliation board
(using 1:1 isolation line isolation transformer) rather than the oscilloscope is highly recommended.
The LM3445 evaluation board should not be powered with an open load. For proper operation, ensure that the desired number of LEDs are connected
at the output before applying power to the evaluation board.
30126901
LM3445 Device Pin-Out
30126902
Pin Description 10 Pin MSOP
Pin # Name Description
1 ASNS PWM output of the triac dim decoder circuit. Outputs a 0 to 4V PWM signal with a duty cycle proportional to the triac
dimmer on-time.
2 FLTR1 First filter input. The 120Hz PWM signal from ASNS is filtered to a DC signal and compared to a 1 to 3V, 5.85 kHz
ramp to generate a higher frequency PWM signal with a duty cycle proportional to the triac dimmer firing angle. Pull
above 4.9V (typical) to tri-state DIM.
3 DIM Input/output dual function dim pin. This pin can be driven with an external PWM signal to dim the LEDs. It may also
be used as an output signal and connected to the DIM pin of other LM3445 or LED drivers to dim multiple LED
circuits simultaneously.
4 COFF OFF time setting pin. A user set current and capacitor connected from the output to this pin sets the constant OFF
time of the switching controller.
5 FLTR2 Second filter input. A capacitor tied to this pin filters the PWM dimming signal to supply a DC voltage to control the
LED current. Could also be used as an analog dimming input.
6 GND Circuit ground connection.
7 ISNS LED current sense pin. Connect a resistor from main switching MOSFET source, ISNS to GND to set the maximum
LED current.
8 GATE Power MOSFET driver pin. This output provides the gate drive for the power switching MOSFET of the buck
controller.
9 V
10 BLDR Bleeder pin. Provides the input signal to the angle detect circuitry as well as a current path through a switched
Input voltage pin. This pin provides the power for the internal control circuitry and gate driver.
CC
230Ω resistor to ensure proper firing of the triac dimmer.
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Bill of Materials
Designator Description Manufacturer Part Number RoHS
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AA1 Printed Circuit Board - Y
U1 Triac Dimmable Offline LED Driver, PowerWise National
Semiconductor
C1 Ceramic, X7R, 250VAC, 10% Murata Electronics
North America
C2 Ceramic, Polypropylene, 400VDC, 10% WIMA MKP10-.033/400/5P10 Y
C3 CAP, CERM, 330pF, 630V, +/-5%, C0G/NP0, 1206 TDK C3216C0G2J331J Y
C4 Ceramic, X7R, 250V, X2, 10%, 2220 Murata Electronics
North America
C5 CAP, Film, 0.033µF, 630V, +/-10%, TH EPCOS Inc B32921C3333K Y
C6 CAP, CERM, 0.015µF, 500V, +/-10%, X7R, 1812 Vishay/Vitramon VJ1812Y223KBEAT4X Y
C7-DNP CAP, CERM, 0.1µF, 630V, +/-10%, X7R, 1812 MuRata GRM43DR72J104KW01L Y
C8 CAP, CERM, 0.1µF, 630V, +/-10%, X7R, 1812 MuRata GRM43DR72J104KW01L Y
C9, C11 CAP, CERM, 1µF, 50V, +/-10%, X7R, 1210 MuRata GRM32RR71H105KA01L Y
C10 CAP, CERM, 0.47µF, 50V, +/-10%, X7R, 0805 MuRata GRM21BR71H474KA88L Y
C12 Aluminium Electrolytic, 680uF, 35V, 20%, Nichicon UHE1V681MHD6 Y
C13 CAP, CERM, 1µF, 35V, +/-10%, X7R, 0805 Taiyo Yuden GMK212B7105KG-T Y
C14 CAP, CERM, 0.1µF, 25V, +/-10%, X7R, 0603 MuRata GRM188R71E104KA01D Y
C15 CAP, TANT, 47uF, 16V, +/-10%, 0.35 ohm, 6032-28
SMD
C16 CAP, CERM, 0.47µF, 16V, +/-10%, X7R, 0603 MuRata GRM188R71C474KA88D Y
C17 CAP, CERM, 0.22µF, 16V, +/-10%, X7R, 0603 TDK C1608X7R1C224K Y
C18 CAP, CERM, 2200pF, 50V, +/-10%, X7R, 0603 MuRata GRM188R71H222KA01D Y
C20 CAP, CERM, 330pF, 50V, +/-5%, C0G/NP0, 0603 MuRata GRM1885C1H331JA01D Y
D1 DIODE TVS 250V 600W UNI 5% SMD Littelfuse P6SMB250A Y
D2 Diode, Switching-Bridge, 600V, 0.8A, MiniDIP Diodes Inc. HD06-T Y
D3 Diode, Silicon, 1000V, 1A, SOD-123 Comchip Technology CGRM4007-G Y
D4 Diode, Schottky, 100V, 1A, SMA STMicroelectronics STPS1H100A Y
D5, D10 Diode, Zener, 13V, 200mW, SOD-323 Diodes Inc DDZ13BS-7 Y
D6 Diode, Zener, 36V, 550mW, SMB ON Semiconductor 1SMB5938BT3G Y
D7, D8, D9 Diode, Schottky, 100V, 150 mA, SOD-323 STMicroelectronics BAT46JFILM Y
F1 Fuse, 500mA, 250V, Time-Lag, SMT Littelfuse Inc 0443.500DR Y
H1, H2, H5, H6 Standoff, Hex, 0.5"L #4-40 Nylon Keystone 1902C Y
H3, H4, H7, H8 Machine Screw, Round, #4-40 x 1/4, Nylon, Philips
panhead
J1, J2 Conn Term Block, 2POS, 5.08mm PCB Phoenix Contact 1715721 Y
L1, L2 Inductor, Radial Lead Inductors, Shielded, 4.7mH,
130mA, 12.20ohm, 7.5mm Radial,
LED+, LED-,
TP7, TP8
Q1 MOSFET, N-CH, 600V, 200mA, SOT-223 Fairchild
Q2 Transistor, NPN, 300V, 500mA, SOT-23 Diodes Inc. MMBTA42-7-F Y
Q3 MOSFET, N-CH, 650V, 800mA, IPAK Infineon
Q4 MOSFET N-CH 100V 170MA SOT23-3 Diodes Inc. BSS123-7-F Y
R1 RES, 221 ohm, 1%, 0.25W, 1206 Vishay-Dale CRCW1206221RFKEA Y
R2, R7 RES, 200k ohm, 1%, 0.25W, 1206 Vishay-Dale CRCW1206200KFKEA Y
R3, R8 RES, 309k ohm, 1%, 0.25W, 1206 Vishay-Dale CRCW1206309KFKEA Y
Terminal, 22 Gauge Wire, Terminal, 22 Guage Wire 3M 923345-02-C Y
AVX TPSC476K016R0350 Y
B&F Fastener Supply NY PMS 440 0025 PH Y
TDK Corporation TSL0808RA-472JR17-PF Y
Semiconductor
Technologies
LM3445MM Y
DE1E3KX332MA5BA01 Y
GA355DR7GF472KW01L Y
FQT1N60CTF_WS Y
SPU01N60C3 Y
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Designator Description Manufacturer Part Number RoHS
R4, R12 RES, 10k ohm, 5%, 0.25W, 1206 Vishay-Dale CRCW120610K0JNEA Y
R5-DNP RES, 680 ohm, 5%, 1W, 2512 Vishay/Dale CRCW2512680RJNEG Y
R6 RES, 820 ohm, 5%, 1W, 2512 Vishay/Dale CRCW2512820RJNEG Y
R10 RES, 430 ohm, 5%, 1W, 2512 Vishay/Dale CRCW2512430RJNEG Y
R11 RES, 49.9k ohm, 1%, 0.125W, 0805 Vishay-Dale CRCW080549K9FKEA Y
R13 RES, 33.0 ohm, 1%, 0.25W, 1206 Vishay-Dale CRCW120633R0FKEA Y
R14 RES, 10 ohm, 5%, 0.125W, 0805 Vishay-Dale CRCW080510R0JNEA Y
R15 RES, 10.0k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW060310K0FKEA Y
R16 RES, 280k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW0603280KFKEA Y
R17 RES, 475k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW0603475KFKEA Y
R18 RES, 49.9k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW060349K9FKEA Y
R19 RES, 10 ohm, 5%, 0.1W, 0603 Vishay-Dale CRCW060310R0JNEA Y
R20 RES, 1.91k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW06031K91FKEA Y
R21 RES, 2.70 ohm, 1%, 0.25W, 1206 Panasonic ERJ-8RQF2R7V Y
R22 RES, 10.7 ohm, 1%, 0.125W, 0805 Vishay-Dale CRCW080510R7FKEA Y
R23 RES, 324k ohm, 1%, 0.1W, 0603 Vishay-Dale CRCW0603324KFKEA Y
RT1, RT2 Current Limitor Inrush, 60Ohm, 20%, 5mm Raidal Cantherm MF72-060D5 Y
T1 FLBK TFR, 2.07 mH, Np=140T, Ns=26T, Na= 20T Wurth Elektornik 750815040 REV 1 Y
TP9, TP10 Terminal, Turret, TH, Double Keystone Electronics 1502-2 Y
VR1 Varistor 275V 55J 10mm DISC EPCOS Inc S10K275E2 Y
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