AL9910EV7 Triac Dimmable 120VAC Evaluation Board - Modification Guide - Date: August 3, 2012 This document contains Diodes confidential and proprietary information (For Internal Use Only) AL9910EV7 120VAC Dimmable Modification Guide August 2012 1. Standard Evaluation Board Schematic 9 5 2 6 4 2 8 7 1 Figure 1: Standard Evaluation Board Schematic 2. Modification Summary Based on the 8 LEDs configuration, we modified the following components to achieve higher efficiency: 1. Inductor (L2) – Coilcraft (MSS1278T-105KLB) with lower conduction and switching losses 2. MOSFET (Q1) – Alpha Omega (AOD4S60) with a low RDS(on) (0.9Ω) and low Qg (6nc) 3. Freewheeling Diode (D2) – Diodes (ES1G-13-F) with a faster recovery time of 25nSec 4. ROSC resistor - Increase R32 to 440KΩ to lower the switching frequency 5. Gate drive resistor – Decrease R6 to 4.73Ω to turn on the MOSFET faster AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 2 of 15 3 AL9910EV7 120VAC Dimmable Modification Guide August 2012 We concluded the overall efficiency can be improved higher using the standard EVB to around 87%. In addition, we connected the 120VAC Lutron dimmer (P/N LG-603PG) at full brightness setting, the efficiency maintained at 80%. 3. Introduction This report shows how to select components and change applications circuitry from the standard EVB to meet certain customer’s requirement. Customers have different requirement for their customized LED applications. We can modify our standard evaluation board to fulfill their needs and shorten the design-in time. Customers usually provide a set of test conditions such as input/output voltage, number of output LEDs, output LED current, output ripple current, power factor, and efficiency. 4. Modifications from Standard EVB Here is a list of parameters that allows user to change the applications circuitry using our standard EVB to meet their customized LEDs requirements: 1. How to adjust output LED current (ILED) User can change the Rsense resistor (R7) and Power Inductor (L2) to a different value to decrease or increase the output LED current. Table below shows typical values for R7 and L2 selection to meet the I LED requirement: Rsense (Ω) 1.91 1.62 1.50 1.20 Power Inductor (mH) 1.0 1.0 1.0 1.0 ILED (mA) 260 425 500 700 2. How to improve efficiency (Eff) Efficiency varies with several parameters: ILED LED current is direct proportional to the intensity of the light. The higher ILED will increase the efficiency based on the power equation, Pout = Vout * ILED. However, user needs to know the current limit of the types of LEDs and not to exceed this limit. AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 3 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 Numbers of LEDs Typical LED voltage is 3.3V, the numbers of LEDs determine the Vout and based on the power equation, Pout = Vout * ILED. When the numbers of LEDs increase, Vout will increase accordingly and affects the efficiency. MOSFET selection Power MOSFET is acting as a switch to regulate the voltage across the output of the LED. In conjunction with the current feedback loop circuitry, when the ILED exceeded the limit, MOSFET will turn off to protect the LEDs. Two main parameters for MOSFETs selection to enhance the efficiency are: Low RDS(on) will reduce the conduction loss and Low Qg will reduce the switching loss. MOSFET Gate Drive Improve the gate drive by lowering R6 from 22Ω to 4.7Ω so the MOSFET will turn on faster and improve the efficiency. Switching Inductor With proper selection of the right inductance value, inductors can delivery system running under continue conduction mode to provide maximum efficiency performance. The following parameters are needed to be defined or calculate for inductance operating in continue conduction mode: Maximum input voltage Minimum input voltage Maximum switching frequency Maximum LED ripple current Duty cycle Select a larger value inductance with +/-20% tolerance. Unfortunately, larger inductance requires more winding and tends to be higher DCR and cost. So the final inductor selection depends on four main design criteria: efficiency, electromagnetic interference (EMI), dimension, and cost. In handheld battery powered applications: high efficiency, low EMI, and smallest spacing are required. For retrofit LED lighting applications, the lowest cost solution is often employed for AC utility supply. Recommend to check each inductor "roll off" and frequency response beside parameters like Irms, Isat, and DCR. Refer to the data sheet for frequency response curves. For EV7 application, use the MSS1260T series high temperature power inductor from Coilcraft. Total inductor loss comes from two factors: inductor core loss which is switching frequency related and DCR loss which is conduction resistance loss. AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 4 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 Free-Wheeling diode Freewheeling diode is used to eliminate flyback, the sudden voltage spike across an inductive load and provide continuously current into the inductor when power MOSFET is suddenly switched OFF. Here are the selection criteria for the diode: Peak forward current capacity (IPEAK), reverse breakdown voltage (VR), and average rectified output current (IO) Lower forward voltage drop (VF) and faster reverse recovery time (trr) are recommended for better power efficiency. 3. How to reduce output ripple User can add a Electrolytic Capacitor with proper voltage rating across LED+ (X3) and LED- (X4) to suppress the amplitude of the output waveform. Install the Electrolytic Capacitor carefully to make sure it will able to fit into the E27/A19 light bulbs housing. Typical Electrolytic Capacitor values shown: Electrolytic Capacitor (µF) 330 µF 50V 470 µF 50V 680 µF 50V 1000 µF 50V Output Ripple Suppressed 7% 26% 46% 60% 4. How to adjust operating switching frequency User can set AL9910 either on constant frequency or constant off time modes. Constant switching frequency Connect a resistor between Rosc pin and Ground pin. Use tosc = (Rosc + 22)/ 25 µs Switching frequency will impact efficiency. Be careful to have Duty cycle > 0.5 and min Ton >Tblank time (smaller number of LED and in low power mode < 3W) when use at constant frequency mode. Constant Off time (Variable Frequency) Connect Rosc between Rosc pin and Gate of external MOSFET. The switching frequency varies as either Vin or Vout changes. More suitable to be used for Triac AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 5 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 Dimming application circuitry that Vin and Vout are changing according to dimmer positions. Help to remove instability issue from Duty cycle > 50%. 5. How to reduce harmonic distortion Harmonic is a measurement of amplitude and frequency of the input source. Harmonic distortion also depends on the numbers of LEDs and ILED. User can add capacitors both at input and output on the EVBs. However, adding components will impact BOM cost. The most economical way is to add just an output capacitor across LED+ (X3) and LED- (X4) and it will reduce the harmonic. For the EV7 application, add a 220µF/50V 20% radial capacitor will be sufficient to reduce the harmonic. 6. How to adjust holding current and dimmer compatibility The AL9910 triac dimming evaluation board includes a bleeder circuit to ensure proper triac operation by allowing current flow while the line voltage is low to enable proper firing of the triac since the existing triac dimmer requires a small amount of a few milliamps of current to hold them on throughout the AC line cycle. An external resistor (R17) needs to be placed on the source of Q2 to GND to perform this function. The R17 resistor can be adjusted independently. As the holding resistor R17 is increased, the overall efficiency will also increase. 7. How to improve triac dimming range The AL9910EV7 evaluation board has been optimized with the dimming circuit for triac dimming controls. It is mainly used for both forward phase and reverse phase dimmers using a 120VAC input. In practice, a triac or electronic dimmer can be inserted in series to the hot line voltage after the AC power supply or AC wall power supply, which is then connected directly to the input of the LED driver board. As the AC power supply can be set at any voltage, normally at 120V AC for the AL9910EV7 evaluation board, the dimmer can be adjusted from maximum dimming range that provides full brightness of LEDs to minimum dimming range that provides the lowest brightness before it completely turns off at a cut-off threshold. For design flexibility for different condition requirements, the value of resistance in the dimming circuit can be selected to provide wide maximum and minimum range of LED dimming. Table below shows maximum and minimum LED dimming ranges: AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 6 of 15 AL9910EV7 120VAC Dimmable Modification Guide Resistor R25 (Refer to figure 2 – Standard EVB’s schematic) R2 (Refer to figure 2 – Standard EVB’s schematic) August 2012 Comment Lower R25 (20 KΩ) to an acceptable value if needed (based on the type of dimmers) to achieve lower LED dimming range Lower R2 (10 KΩ) to an acceptable value if needed (based on the type of dimmers) to achieve higher LED dimming range Here is a list of Triac dimmers which were tested in our lab: Model Number Voltage (VAC Input) 1 LG-603PG 120 2 DV-603PG 120 DV-600P 120 4 CTCL-153PD 120 5 TGCL-153P 120 6 D106P 120 SLC03P 120 NOM426 120 Item # 3 7 Dimmer Type Lutron Copper 8 AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 7 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 Test Fixture AC Input (90V to 130V) AL9910EV7 Triac Dimmer LEDs bank 8. How to adjust Power Factor Correction (PFC) EV7 power factor correction circuitry contains R42, R43, R44 and Q6. It works as a controlled voltage divider added into the current feedback loop to have the input current waveform matched with the voltage waveform will improve the power factor. But adjust R42 and R44 to have a high power factor may hurt LED current line rejection tolerance. Disable this circuitry to replace with valley-fill circuitry which is a passive power factor correction. It can maintain a stable LED current over line voltage variation and good power factor at a higher BOM cost trade off. 9. How to improve Electromagnetic Interference (EMI) Standard EV7 did not come with line EMI filter. EMI results may relate to customer's PCB layout, power source, loading conditions, LED lamp fixtures designs, components selection, switching frequency, and EMI filter design. User may consider using: Common mode filter (ELF-11090E) Differential mode inductor (MSS1260-105KL-KLB) Choke RF Shielded inductor (RL875S) for EMI enhancement. However, it will need a joined collaboration with sharing AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 8 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 product information between customers and Diodes application supporting team to develop an optimize EMI solution. AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 9 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 5. Standard Evaluation Board Connections Board Dimension (components included): WxLxH (in mm) = 20mm x 33mm x 19mm LED+ LED- AC- AC+ Figure 2: Top-View Board Recommended Test conditions: Input Voltage: 120VAC, 60Hz LED Output Voltage: 24VDC LED Output Current: 300mA Efficiency: 87%. Note: Use the MOSFET (Q1 - AOD4S60) and lower the gate drive resistor R6 to 4.7Ω. Connection Instructions: AC+ (X1) Input: Red – Hot AC- (X2) Input: Black - Neutral DC LED+ (X3) Output: LED+ (Red) DC LED- (X4) Output: LED- (Black) AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 10 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 6. Standard AL9910A Pin Assignment and Description AL9910A Pin Assignment (Top View) VIN 1 CS GND 2 Gate 8 Rosc 3 7 6 LD VDD 4 5 PWM_D AL9910A SO-8 AL9910A Pin Description Pin Name Pin Number VIN CS GND Gate 1 2 3 4 PWM_D 5 VDD 6 LD 7 ROSC 8 AL9910EV7 Rev 1 (8/3/2012) Description Input voltage Senses LED string current Device ground Drives the gate of the external MOSFET Low Frequency PWM Dimming pin, also Enable input. Internal 100kΩ pull-down to GND Internally regulated supply voltage. 7.5V nominal for AL9910. Can supply up to 1mA for external circuitry. A sufficient storage capacitor is used to provide storage when the rectified AC input is near the zero crossings Linear Dimming by changing the current limit threshold at current sense comparator Oscillator control. A resistor connected between this pin and ground sets the PWM frequency. - For Internal Use Only - Page 11 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 7. Standard Evaluation Board BOM List Item Comment C1 C1206 0.047u 630V C4, C0603 4.7u 16V C6, C41 C0603 1u 16V C5 C7, C8, C12 C9, C13, C14 C0402 220p 50V C0603 0.1u 16V C0805 – 4.7u 50V C10 C1206 – 1n 500V C11 C0603 – 4.7u 10V C15 C0805 0.022u 450V C40 C0603 – 2.2u 16V C42 C1206 – 0.22u 250V X5X6 C0.22µF, 250V D1 HD06 D2 D3, D5, D8 MURS160 D6 1N4148WT SRR6028681Y L1 SM4005PLTP AL9910EV7 Rev 1 (8/3/2012) Description Multilayer Ceramic Capacitors (1206) 0.047µF 630V 10% Multilayer Ceramic Capacitors (0603) 4.7µF 16V 10% Multilayer Ceramic Capacitors (0603) 1.0µF 16V 10% Multilayer Ceramic Capacitors (0402) 220pF 50V 5% Multilayer Ceramic Capacitors (0603) 0.1µF 16V 10% Multilayer Ceramic Capacitors (0805) 4.7µF 50V 10% Multilayer Ceramic Capacitors (1206) 1nF 500V 10% Multilayer Ceramic Capacitors (0603) 4.7µF 10V 10% Multilayer Ceramic Capacitors (0805) 0.022µF 450V 10% Multilayer Ceramic Capacitors (0603) 2.2µF 16V 10% Multilayer Ceramic Capacitors (1206) 0.22µF 250V 10% Polyester Film Capacitor Bridge Rectifiers 0.8A, 600V Super-Fast Rectifiers 1.0A, 600V Diode SIL 1.0A, 600V Fast Switching Diode 100V Power Inductors 680µH 220mA Size Qty Manufacturer Part Number C1206 1 Murata C3216X7T2J473M/SOFT C0603 1 TDK C1608X5R1C475M C0603 2 TDK C1608X7R1C105K C0402 1 Murata GRM155R71H221JA01J C0603 3 Murata GCM188R71C104KA37D C0805 3 TDK C2012X5R1H475K C1206 1 Vishay/Vitramon VJ1206Y102KXEAT5Z C0603 1 AVX 0603ZD475KAT2A C0805 1 TDK C2012X7T2W223K C0603 1 TDK C1608X5R1C225KT C1206 WxLxH (mm) 5.5 x 10.3 x 15.5 1 TDK C3216X7T2E224K 1 Panasonic ECQ-E2224JB MiniDip 1 Diodes Inc HD06-T SMB 1 Diodes Inc MURS160-13-F 3 Micro Commercial Co SM4005PL-TP 1 Diodes Inc 1N4148WT-7 1 Bourns SRR6028-681Y Power lite 123 SOD523 L6028 - For Internal Use Only - Page 12 of 15 AL9910EV7 120VAC Dimmable Modification Guide L2 7447709102 Q1 STD7NM60N Q2 SPD01N60C3 Q6 BC847C R1 S07K300 R2 R1206 – 10k R3 R6, R40 R0402 - 2k R7 R0805 - 1.62 R9 R0402 - 1k R10 R0805 - 10k R11 R0402 - 2.2M R12 R13 R0402 - 200k R1206 – 4.7M R14 R1206 - 348k R15 R0402 - 4.3k R16 R0402 - 120k R17 R1206 – 249 R47 R18, R20 R1206 – 200 R19 R0402 - 1.2M R21 R0805 - 510k R22 R0402 - 300k R23 R1206 - 750k R35 R0805 - 750k R0402 - 22 R0805 - 1M AL9910EV7 Rev 1 (8/3/2012) Power Inductors 0.9A, 1mH MOSFET Power NChan 600V, 5 Amp MOSFET Power COOL MOS N-CH 650V, 0.8A NPN Surface Small Signal Transistor 100mA, 45V Varistors 300Vrms 7MM Radial Chip Resistor (1206) 10kΩ 1/10W 1% Chip Resistor (0402) 2kΩ 1/10W 1% Chip Resistor (0402) 22Ω 1/10W 1% Chip Resistor (0805) 1.62Ω 1/8W 1% Chip Resistor (0402) 1kΩ 1/10W 1% Chip Resistor (0805) 10kΩ 1/8W 1% Chip Resistor (0402) 2.2MΩ 1/10W 5% Chip Resistor (0402) 200kΩ 1/10W 1% Chip Resistor (1206) 4.7MΩ 1/4W 5% Chip Resistor (1206) 348kΩ 1/4W 1% Chip Resistor (0402) 4.3kΩ 1/10W 1% Chip Resistor (0402) 120kΩ 1/10W 1% Chip Resistor (1206) 249Ω 1/4W 1% Chip Resistor (1206) 200Ω 1/4W 1% Chip Resistor (0805) 1MΩ 1/8W 1% Chip Resistor (0402) 1.2MΩ 1/10W 5% Chip Resistor (0805) 510kΩ 1/8W 1% Chip Resistor (0402) 300kΩ 1/10W 1% Chip Resistor (1206) 750kΩ 1/3W 5% Chip Resistor (0805) 750kΩ 1/4W 5% August 2012 L12.5 x 12.5 x 10 1 D-PAK 1 Wurth Electronics ST Microelectronics D-PAK 1 Infineon SPD01N60C3 1 Diodes Inc BC847C-7-F 1 EPCOS Panasonic ECG Panasonic ECG Panasonic ECG S07K300 Vishay Panasonic ECG Panasonic ECG Panasonic ECG Panasonic ECG Rohm Semiconductor CRCW08051R62FKEA Vishay/Dale Panasonic ECG Panasonic ECG Rohm Semiconductor Panasonic ECG Panasonic ECG Panasonic ECG Panasonic ECG Panasonic ECG Panasonic ECG Panasonic ECG CRCW1206348KFKEA SOT23 Disc 7mm R1206 1 R0402 1 R0402 2 R0805 1 R0402 1 R0805 1 R0402 1 R0402 1 R1206 1 R0805 1 R0402 1 R0402 1 R1206 1 R1206 1 R0805 2 R0402 1 R0805 1 R0402 1 R1206 1 R0805 1 - For Internal Use Only - 7447709102 STD7NM60N ERJ-P8J103V ERJ-2RKF2001X ERJ-2RKF22R0X ERJ-2RKF1001X ERJ-6ENF1002V ERJ-2GEJ225X ERJ-2RKF2003X MCR18EZHJ475 ERJ-2RKF4301X ERJ-2RKF1203X MCR18EZHF2490 ERJ-8ENF2000V ERJ-6ENF1004V ERJ-2GEJ125X ERJ-6ENF5103V ERJ-2RKF3003X ERJ-P08J754V ERJ-P06J754V Page 13 of 15 AL9910EV7 120VAC Dimmable Modification Guide R25 R0402 - 20k R29 R0603 - 180k R32 R0402 - 360k R41 R42 R0402 - 750k R1206 – 1.6M R43 R0402 - 200 R44 R0402 - 4.7k R45 R0402 - 100k R46 R0402 - 150k R47 R48 R1206 – 390 Thru-hole – 150 R49 R1206 – 15k U1 AL9910ASP -13 U2 LM2903 AL9910EV7 Rev 1 (8/3/2012) Chip Resistor (0402) 20kΩ 1/10W 1% Chip Resistor (0603) 180kΩ 1/10W 1% Chip Resistor (0402) 360kΩ 1/10W 1% Chip Resistor (0402) 750kΩ 1/10W 1% Chip Resistor (1206) 1.6MΩ 1/4W 5% Chip Resistor (0402) 200Ω 1/10W 1% Chip Resistor (0402) 4.7kΩ 1/10W 1% Chip Resistor (0402) 100kΩ 1/10W 1% Chip Resistor (0402) 150kΩ 1/10W 1% Chip Resistor (1206) 390Ω 1/3W 5% Through-hole 150Ω 1/2W 5% Chip Resistor (1206) 15kΩ 1/3W 5% LED Drivers - 10V LED Driver PWM 85 to 277VAC Comparator IC - Low Power Dual Voltage R0402 1 R0603 1 R0402 1 R0402 1 R1206 1 R0402 1 R0402 1 R0402 1 R0402 1 R1206 1 Axial 1 R1206 1 SO8EP 1 SO-8 1 - For Internal Use Only - Rohm Semiconductor Panasonic ECG Panasonic ECG Panasonic ECG Rohm Semiconductor Panasonic ECG Panasonic ECG Panasonic ECG Panasonic ECG Rohm Semiconductor Panasonic ECG Rohm Semiconductor Diodes Inc ST Microelectronics August 2012 TRR01MZPF2002 ERJ-3EKF1803V ERJ-2RKF3603X ERJ-2RKF7503X MCR18EZHJ165 ERJ-2RKF2000X ERJ-2RKF4701X ERJ-2RKF1003X ERJ-2RKF1503X ESR18EZPJ391 ERD-S1TJ151V ESR18EZPJ153 AL9910ASP-13 LM2903DT Page 14 of 15 AL9910EV7 120VAC Dimmable Modification Guide August 2012 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). 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Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perfor m can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support d evices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diod es Incorporated products in such safety-critical, life support devices or systems. Copyright © 2012, Diodes Incorporated www.diodes.com AL9910EV7 Rev 1 (8/3/2012) - For Internal Use Only - Page 15 of 15