IS31LT3938 Bulb Lighting DEMO Board Guide Description IS31LT3938 LED driver IC is a peak current detection buck converter which operates in constant off time mode. It operates over a very wide input voltage supply range of 10VDC to 450VDC or 110VAC/220VAC. IS31LT3938 incorporates the special feature of power sequencing by detecting OFF-ON cycles of the main power switch. When the switch is cycled within a 4 second period (typical) the device automatically switches the power sequencing level to the next step. As a result, power sequencing can be achieved without replacing any wiring in the original system. There are multiple modes of power sequencing that the user may configure, 2 steps or 3 steps, as well as different levels of power sequencing via the external pins DIM1 and DIM2. Features User configurable power sequencing levels 3% output current accuracy Over current, voltage and temperature protection High efficiency (typical up to 95%) Wide input voltage range: 10VDC-450VDC or 85Vac-265Vac Linear and PWM dimming Very few external components LED array(7 LEDs in series) Recommended Input and Output Ratings Input: 85~265VAC Output: 7LEDs in series(23V)/330mA Absolute Maximum Ratings ≤ 265VAC power supply ≤ 26V Vout (Total Vf) Caution: Do not exceed the conditions listed above, otherwise the board will be damaged or the output will be limited. Procedure The IS31LT3938 DEMO Board is fully assembled and tested. Follow the steps listed below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. 1) Connect the positive terminal of the LEDs to the LED+ pin of the DEMO and the negative terminal of the LEDs to the LEDpin of the DEMO. 2) Connect the input pins (L and N) of the DEMO via the main power switch to AC power supply. 3) Turn on the power supply. Detailed description Switchable Power Levels Applications DC/DC or AC/DC LED driver applications Signal and decorative LED lighting backlighting LED driver Order information Part Number Package Type IS31LT3938-GRLS2-EBBULB SOP-8 Quick Start Recommended Equipment 85~265VAC/50~60Hz power supply Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 The action of the main power switch can be divided into two types. The first is “normal switch operation” wherein the switch is toggled from ON to OFF, remaining OFF for longer than 4 seconds (typical). The other is “power sequencing action” wherein the switch is toggled from ON to OFF and back ON within 4 seconds (typical). When the device experiences normal switch 1 IS31LT3938 Bulb Lighting DEMO Board Guide operation, it merely powers on in the first state when the power switch is toggled to ON, and the device turns off when the main power switch is changed to OFF. Power sequencing output current levels are configured by connecting the DIM1 and DIM2 pins as indicated in the table below： DIM1 DIM2 Power sequencing levels Floating Floating No Power Sequencing Floating GND 2levels：100%-30%-100% GND Floating 2levels：100%-50%-100% GND GND 3levels:100%-50%-20%-100% When operating the power switch normally the device will always power up at 100% output current. The operation of the power switch and the configuration of the DIM1 and DIM2 pins control the power sequencing process as follows： 1. When DIM1 and DIM2 pins are both floating, there is no power sequencing, and the output current is 100% of the programmed value when the power is on. 2. When DIM1 is floating and DIM2 is GND, the output current is： a) 100% at power on. b) The first power sequencing action causes the current to change to 30%. Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 c) A second power sequencing action causes the current to return to 100%. d) A fourth power sequencing action has the same effect as the first power sequencing action. e) Subsequent power sequencing actions causes the cycle to continue. 3. When DIM1 is GND and DIM2 is floating, the power sequencing is as described in (2) above, except that the current sequencing is 100%-50%-100%. 4. When both DIM1 and DIM2 are connected to GND, the power sequencing is as described in (2) above, except that the current sequencing is 100%-50%-20%-100%. If the switch is operated normally, that is, switched on once after being in the OFF position for a long time, or if both the DIM1 and DIM2 pins are floating, then the output current always starts up at the initial value of 100%. Note: Because the main power switch is used to initiate the power sequencing function, the device must have a large enough external capacitor on VIN to maintain device operation for 4 seconds. Please refer to the Applications Examples for specific values. 2 IS31LT3938 Bulb Lighting DEMO Board Guide Bill of Materials No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Name Fuse AL Cap SMD Cap Inductor Inductor EE Inductor Rectifying Bridge Zener Diode FR Diode Resistor Resistor Resistor Resistor Resistor NMOS PCB IC Description 1A,250V,3*10 10uF±10%,400V 10uF±20%,25V,0805 3mH±10%,8*10mm,Isat≥200mA 4.7uH±10%,5.6*5.6mm ,Isat≥1A 1.8mH±5%,Isat≥700mA,EE13 0.5A,600V, SOIC-4 12V,0.25W,LL-34 1A,600V,ES1J,SMA NC 75KΩ±5%,1W 470KΩ±1%,0805 1.5Ω±1%,1206 0.91Ω±1%,1206 4N60,4A/600V,TO-251 47mm x 20mm IS31LT3938,SOP-8 Total Cost(Exclude IC) Ref Des. F1 C2,C6 C4 L1 L4 L6 BR1 D2 D1,D4 R1 R3-1,R3-2 R5 R9 R10 Q1 U1 Qty. 1 2 1 1 1 1 1 1 2 1 2 1 1 1 1 1 1 Cost(RMB) 0.1 0.4 0.1 0.15 0.3 0.8 0.3 0.1 0.3 0 0.02 0.006 0.008 0.008 1.5 0.28 4.372 Note: 1. If the input voltage is single voltage(85~130VAC or 178~265VAC), L4 and D1 can be removed (short the L3 and eliminate D3) and the efficiency will be higher. 2. If adding the opto-couple as the open output voltage limitation, C6 can use 35V tolerance rating to saving size and decreasing the output current ripple. Figure 1. Picture of DEMO Board NOTE: Physical dimensions are (L x W x H): 47mm x 20mm x 19mm Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 3 IS31LT3938 Bulb Lighting DEMO Board Guide Figure 2. Schematic of DEMO Board Figure 3. PCB Layout- Top Layer Figure 4. PCB Layout- Bottom Layer Figure 4 Component Placement Guide -Top Layer Figure 5 Component Placement Guide -Bottom Layer Test result Line regulation Output Output Output current(mA) voltage(V) power(W) 0.599 318 23.09 7.34262 86.49 8.51 0.598 319 23.09 7.36571 86.55 100 8.58 0.590 322 23.09 7.43498 86.65 110 8.69 0.579 325 23.09 7.50425 86.36 120 8.78 0.566 328 23.09 7.57352 86.26 130 8.87 0.550 330 23.10 7.623 85.94 180 9.26 0.491 333 23.11 7.69563 83.11 200 9.52 0.470 337 23.18 7.81166 82.06 220 9.90 0.453 345 23.21 8.00745 80.88 240 10.09 0.439 345 23.21 8.00745 79.36 265 10.42 0.426 348 23.21 8.07708 77.52 Input Input voltage(VAC) power(W) 85 8.49 90 PF Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 Efficiency(%) 4 IS31LT3938 Bulb Lighting DEMO Board Guide 100 500 95 450 90 400 80 75 350 70 Efficiency Iout(mA) Efficiency(%) 85 Iout 300 65 60 250 55 200 50 85 105 125 145 165 185 205 225 245 265 Vin(VAC) Loading regulation Input voltage(VAC) Input power(W) PF Output current(mA) Output voltage(V) Output power(W) Efficiency(%) 220 8.55 0.413 367 18 6.606 77.26 220 8.81 0.415 362 19 6.878 80.44 220 8.99 0.417 359 20 7.180 79.86 220 9.37 0.421 354 21 7.434 79.33 220 9.30 0.424 345 22 7.590 81.60 220 9.82 0.426 343 23 7.889 80.33 220 9.99 0.428 337 24 8.088 80.96 220 10.16 0.430 333 25 8.325 81.93 220 10.30 0.432 328 26 8.528 82.79 220 10.45 0.435 320 27 8.640 82.67 220 10.52 0.455 314 28 8.792 83.57 Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 5 Efficiency(%) IS31LT3938 Bulb Lighting DEMO Board Guide 100 400 95 380 90 360 85 340 80 320 75 300 70 280 65 260 60 240 55 220 50 Efficiency Iout 200 18 19 20 21 22 23 24 25 26 27 28 Vout(V) Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 6 IS31LT3938 Bulb Lighting DEMO Board Guide EMI test Figure 6. L line Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 7 IS31LT3938 Bulb Lighting DEMO Board Guide Figure 7. N line Copyright © 2011 integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. – www.issi.com R1.2, 6/26/2013 8