ISL6745ALEVAL3Z: TRIAC Dimmer Compatible High Brightness White LED Driver ® Application Note July 28, 2009 Abstract AN1487.0 Configuration with Phase Controlled Triac Wall Dimmer The ISL6745ALEVAL3Z is a low cost, high performance LED driver with power factor correction function, and is compatible with the widely used wall dimmers. It uses Intersil’s voltage mode PWM controller ISL6745A to operate a SEPIC converter in discontinuous conduction mode (DCM). The design gives high flexibility on both the input side and output load. With the same circuit configuration, it works well with and without a triac dimmer. While connecting to any AC source from 50V to 140V without dimmer, it gives high power factor correction with high waveform factor of the input current. As it is powered through a phase controlled wall dimmer, the averaged rectified voltage varies as to the phase angle of the wall dimmer. The brightness of the LED is dimmed by changing the LED current, which is proportional to the averaged rectified voltage. This driver circuit can be used for various LED lighting applications. The number of LEDs in a string can be as many as 14, or as few as 4. Therefore, this design provides the luminaire manufacturers a high performance, low-cost solution for LED drivers compatible with the TRIAC phase-control dimmers. • Input VAC: 80V~ 140V • Efficiency η: 78% • Output Current ILED: 10mA ~ 670mA • Output Voltage VOUT: 10V ~ 46V • Switching Frequency Fs: 100kHz • Output Voltage Ripple VRPP: 50mV(P-P) The System Block Diagram is shown in Figure 1, where the triac phase controlled dimmer chops the AC voltages, and the bridge rectifies it so the voltage applied to the SEPIC converter (L1, L2, C2, Q1, D) is rectified chopped AC voltage. The duty ratio of the SEPIC switch Q1 is controlled by the voltage mode PWM controller ISL6745A. The modulation signal VERR is derived from the current control circuit integrating the difference between the measured current of the LED string ( K RS ILED) and the reference current signal (Vx). The circuit is implemented with Intersil’s high performance rail-to-rail op-amp EL5420. The reference signal (Vx) is derived from the rectified AC voltage over C1, |VAC|. Design Specifications Configuration with Sinusoidal AC Source The top and bottom view of the evaluation board ISL6745ALEVAL3Z is shown in Figure 2. The detailed design procedure for a discontinuous conduction mode (DCM) SEPIC converter with power factor correction (PFC) is discussed in Application Note AN1411, available on Intersil’s website. • Input VAC: 50V ~140V • Typical Power Factor PF: 0.98 • Typical Efficiency η: 80% • Output Current ILED: 10mA ~ 670mA • Output Voltage VOUT: 10V ~ 46V • Switching Frequency FS: 100kHz • Output Voltage Ripple VRPP: 50mV(P-P) |VAC| C2 L1 D R1 AC C1 Q1 LED C0 STRING L2 RCS TRIAC DIMMER Rs BRIDGE PWM DIMMING REFERENCE GENERATING ISL6745A VERR PWM CONTROLLER EL5420 OP AMP CURRENT CONTROLLER VX FIGURE 1. SYSTEM BLOCK DIAGRAM 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1487 capacitor is not suitable for this purpose, because of its high ESR and dielectric loss. Instead, a high frequency film capacitor such as metallized mylar or polypropylene should be used. FIGURE 3. TYPICAL VOLTAGE AFTER THE TRIAC DIMMER A damper resistor R1 is needed to reduce the ringing effect because of the high dv/dt caused by the phase-angle dimming control of the triac. A minimum resistance should be used to ensure as low as possible power loss, while achieving normal dimming function. This resistor can be shorted if the driver is not triac dimmer controlled. L1 and L2 are selected so that the converter operates in DCM. The details of the design of the two inductors and capacitor C2 can be found in Application Note AN1411. FIGURE 2. TOP AND BOTTOM VIEW OF LED DRIVER Circuit Description Unlike the active power factor correction converters, a voltage follower works in discontinuous conduction mode with comparatively constant duty ratio (D) within each utility cycle. There is no need for a PFC controller, or input voltage/current sense circuit. A simplified block diagram is shown in Figure 4. A typical waveform of the voltage after a triac dimmer is shown in Figure 3, where high dv/dt is noticed as the triac is turned on. A small capacitor C1 is recommended here to filter out the switching noises. C1 should be very small so that the voltage across it follows closely the rectified input voltage |VAC|. An Electrolytic One simple and low-cost solution for LED lamp brightness dimming is to control the LED current. It is assumed that the brightness of the LED lamp is linearly proportional to its current in normal conditions. Although the tune and color may change with operating current, the current based dimming method is acceptable for common LED luminaire applications. The current reference signal is in proportion to the averaged rectified voltage |VAC| . The average voltage versus the phase angle α of triac dimmer is shown in Figure 5 for a commercial dimmer. IIN D1 D3 IO P1 P0 POWER C1 CONVERTER AC D2 C0 R0 D4 PWM POWER CONTROLLER Vo FIGURE 4. VOLTAGE FOLLOWER BLOCK DIAGRAM 2 AN1487.0 July 28, 2009 Application Note 1487 |VAC| R4 90 VB2 80 VDD 5V1 2 R6 1.0M 60 1 1A 50 BAT54C R22 3V6 2 70 CR3 1 Q0 R24 10.0k 1% 3 40 R23 10.0k 1% 1k C15 10n 3 AVERAGE RECTIFIED VOLTAGE (V) 100 30 VR1 R16 DNP 20 C7 C27 C12 µF 47u 47u µF 220n VR3 5.1V VR4 18V R25 14.0k 1% 10 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 PHASE WIDTH OF TRIAC (MS) 6.0 6.5 FIGURE 8. BIAS CIRCUIT FIGURE 5. AVERAGE VOLTAGE vs ANGLE OF A TRIAC DIMMER The schematic diagram of the current reference circuit is shown in Figure 6, where |VAC| is the rectified voltage after the rectifier. The high performance Op-Amp EL5420 clamps the current reference if the averaged input of U3A is beyond the bias voltage. |VAC| R8 1% 100k R9 100k 1% R29 BAT 54 CR4 VX 3 1 2 C5 DNP R10 14.3k 1% C6 R32 2.2µF 150k 11 2 EL5420 U3A 3 + 4 C20 6.8µF 1 R27 10.0k 1% R28 59.0k 5V1 1% 5V1 IREF 10.0k 1% IREF 5V1 R31 10.0k 1% C26 2.2µF C25 1.2n FIGURE 6. REFERENCE CIRCUIT The LED current reference can be changed through R10 and R29 for applications with different rated operating current. Figure 7 shows the LED current control circuit, where U4C provides 10 times of gain to reduce the power loss in the current sense resistor Rs. The integration circuit implemented with U3B eliminates any discrepancy between the reference (IREF) and the LED current (ILED). The time constant set by C19 and R33 should be large enough so that the second order harmonics will not appear in the control signal. A typical way is to set the time constant to 0.5 times of the utility frequency. The bias circuit is shown in Figure 8 together with the reference voltages for the control circuit. At the beginning, the |VAC| increases so that the voltage at the gate of Q0 is about 12V, Q0 is turned on, and C7 is charged up with |VAC| through R4. The ISL6745A starts to work as soon as the VDD is above its threshold. The output capacitor is charged up once the converter begins to work. The VB2 presents an alternative bias choice for the driver for high voltage applications. If it is connected to the 3rd of the LED strings, 3 times of p-n junction voltage presents when LED strings start conducting current. This will shut off the current path of Q0, CR3, and prevents the Q0 from conducting current in normal operation conditions. The following circuit in Figure 9 shows a soft-start circuit with overvoltage protection and delayed start-up circuit. The VR2, R39, R15 set up the over voltage protection of the output voltage applied to LED strings. For an overvoltage of any reasons, the Q3 will be turned on, and the SS charges will be discharged through R15. In order to suppress the LED over-shot current during start-up, a delayed start-up circuit consisting of U4D and Q5 is necessary. Only after SS voltage is beyond 3.6V, the Q5 will be turned off, and Vx is presented in the reference generation circuit. This greatly reduces the over-shot of the LED strings during start-up. R11 100 SS 3V6 VX 5V1 R18 11 C21 DNP 6 + 5 7 U3B EL5420 5V1 4 IREF R33 61.9k 1% 1% IREF 5V1 4 C19 2.2µF - VERR 3.01M 10 ISEN + 8 U4C EL5420 C10 ILED 9 0.1µF R3411 196k R35 10.0k C16 BSS138 6.8µF 4 Q5 12 + 14 U4D 13 EL5420 11 SS R15 51.1 2 VERR 3 OUT BSS138 24V OUT Q3 VR2 5 30.1k R39 1.0k C24 0.1µF 4 R19 R26 1% 2k C28 1.2n C17 220p U1 SS RTD VDD VDDP VERR OUTB CS OUTA CT GND 10 VDD 9 C13 470n 8 7 Gate 6 ISL6745A C18 470p 5% C0G OVP FIGURE 9. CONFIGURATION OF ISL6754A, SOFT-START-UP AND OVERVOLTAGE PROTECTION 10X FIGURE 7. CURRENT CONTROL LOOP 3 VX 1 CS The overall schematics of the driver and the associated BOM are presented in the last pages of this application note. The fixture of the PCB is a 2-layer board with dimensions 3.15 by 2.65 inches. Figures 10 and 11 show the top view AN1487.0 July 28, 2009 Application Note 1487 and bottom view of the PCB layouts. Gerber files for the ISL6745ALEVAL3Z board are available upon request. Performance Characteristics Without Dimmer The performance of the LED driver board will be evaluated with and without dimmer respectively in the next sessions for various operation conditions. The schematics and BOM without dimmer are shown in the last pages of this document. Connect the P1 and P2 of the LED driver board to the AC power supply. A string of 6 Cree high power white LEDs areconnected to the output terminal of the LED driver board. The efficiency of the driver is shown in Table 1. The operation waveforms are shown in Figures 12 to 18. Figures 12 to 15 show the rectified input voltage and current for different inputs. Channel 1 (yellow) shows the rectified input voltage (100V/DIV). Channel 4 (green) shows the input current (200mA/DIV). The input voltage and input current waveforms in Figure 16 shows the driver turning off within 2s. Figures 17 and 18 show the overshot of the LED. Current is greatly reduced with the delayed start-up circuit. TABLE 1. EFFICIENCY AND POWER FACTOR WITHOUT DIMMER FIGURE 10. TOP VIEW OF THE PCB LAYOUT VAD (RMS) (V) I INPUT (mA) POWER IN (W) I LED (mA) V/LED (V) 140.25 126 15.43 0.673 18.584 0.8720 81.06 130.20 132 15.49 0.673 18.581 0.8972 80.73 120.12 140 15.52 0.672 18.587 0.9212 80.48 110.11 149 15.53 0.672 18.584 0.9427 80.41 100.09 162 15.54 0.675 18.589 0.9585 80.74 90.08 176 15.51 0.671 18.584 0.9761 80.40 80.07 178 14.04 0.611 18.412 0.9811 70.06 170 11.79 0.521 18.167 0.9875 80.28 60.05 162 9.68 0.430 17.983 0.9899 79.88 50.04 151 7.55 0.338 17.738 0.9947 79.41 40.03 138 5.51 0.245 17.503 0.9974 77.83 30.02 116 3.48 0.152 17.085 0.9979 74.62 20.01 77 1.52 0.058 16.420 0.9956 62.66 V/INPUT C4: IIN, 200mA/DIV PF EFF (%) 80.13 C1: VIN, 100V/DIV I/INPUT FIGURE 11. BOTTOM VIEW OF PCB LAYOUT FIGURE 12. INPUT VOLTAGE AND CURRENT @ 140V 4 AN1487.0 July 28, 2009 Application Note 1487 V/INPUT C1: VIN 100V/DIV C1: VIN 100V/DIV V/INPUT C4: IIN 200mA/DIV I/INPUT C4: IIN 200mA/DIV I/LED FIGURE 13. INPUT VOLTAGE AND CURRENT @ 110V C1: VIN 100V/DIV FIGURE 16. FAST TURN-OFF @ 110V V/INPUT V/INPUT C1: VIN 100V/DIV I/LED C4: IIN 200mA/DIV I/INPUT FIGURE 14. INPUT VOLTAGE AND CURRENT @ 90V C4: IIN 200mA/DIV FIGURE 17. TURN ON OVER-SHOT @ 110V V/INPUT C1: VIN 100V/DIV V/INPUT C4: IIN 200mA/DIV I/INPUT C1: VIN 100V/DIV I/LED C4: IIN 200mA/DIV FIGURE 15. INPUT VOLTAGE AND CURRENT @ 60V 5 FIGURE 18. TURN ON OVER-SHOT @ 80V AN1487.0 July 28, 2009 Application Note 1487 Typical Performance Characteristics with Dimmer See “Schematic With/Without Triac Dimming Compatible” on page 8, tables 5 and 6. Connect the P1 and P2 of the LED driver board to the AC power supply. A string of 6 Cree high power white LEDs is connected to the output terminal of the LED driver board. The efficiency of the driver is shown in Table 2 for 110V input. The operation waveforms are shown in Figures 19 to 24, respectively. Figures 19 to 22 show the rectified input voltage and current for different inputs. Figures 23 and 24 show the overshot of the LED. Current is greatly reduced with the delayed start-up circuit. V/INPUT C1: VIN 100V/DIV I/INPUT C4: IIN 200mA/DIV FIGURE 20. PHASE CONTROLLED VOLTAGE AND INPUT CURRENT TABLE 2. EFFICIENCY AND POWER FACTOR WITH DIMMER PHASE WIDTH (ms) POWER INPUT (W) I LED (mA) V LED (V) PF EFF (%) 7.436 16.99 0.671 18.332 0.99 72.40 5.844 15.064 0.600 18.011 0.94 71.74 5.212 12.428 0.501 17.777 0.87 71.66 4.512 10.212 0.401 17.608 0.75 69.14 3.984 7.758 0.300 17.443 0.64 67.45 3.404 5.100 0.200 17.182 0.51 67.38 2.588 2.629 0.093 16.724 0.35 59.16 1.808 0.756 0.015 15.851 0.17 31.45 V/INPUT C1: VIN 100V/DIV I/INPUT C4: IIN 500mA/DIV FIGURE 21. PHASE CONTROLLED VOLTAGE AND INPUT CURRENT V/INPUT C1: VIN 100V/DIV V/INPUT C1: VIN 100V/DIV I/INPUT C4: IIN 200mA/DIV FIGURE 19. PHASE CONTROLLED VOLTAGE AND INPUT CURRENT 6 I/INPUT C4: IIN 500mA/DIV FIGURE 22. PHASE CONTROLLED VOLTAGE AND INPUT CURRENT AN1487.0 July 28, 2009 Application Note 1487 Thermal Performance Characteristics V/INPUT The temperature test of the board, and critical components of the driver with/without dimmer is shown in Tables 3 and 4 for 110V input full load conditions. C1: VIN 100V/DIV TABLE 3. CIRCUIT WORK WITHOUT DIMMER FOR 6 LEDS I/LED COMP T = +85°C T = +25°C T = 0°C T = -40°C Q1 98 36 11 -30 L1 88 26 3 -35 L2 90 33 3 -34 L3 88 26 3 -37 C4 88 26 3 -37 R4 86 26 0 -37 R12 97 37 13 -26 Q0 89 33 3 -34 CR2 109 49 10 -24 C8 88 29 3 -37 C4: IIN 200mA/DIV FIGURE 23. OVERSHOT OF LED CURRENT (672mA, 9%) V/INPUT C1: VIN 100V/DIV TABLE 4. CIRCUIT WORK WITHOUT DIMMER FOR 6 LEDS I/LED C4: IIN 200mA/DIV COMP T = +85°C T = +25°C T = 0°C T = -40°C Q1 100 38 13 -28 L1 88 30 2 -37 L2 88 30 2 -37 L3 88 28 2 -37 C4 88 28 2 -37 R3 126 84 50 -18 R12 95 37 10 -25 Q0 90 30 5 -34 CR2 92 48 7 -32 C8 88 28 2 -37 FIGURE 24. OVERSHOT OF LED CURRENT (600mA, 8%) V/INPUT C1: VIN 100V/DIV References 1. ISL6745A datasheet, Intersil Corporation 2. ISL5420 datasheet, Intersil Corporation I/LED C4: IIN 200mA/DIV 3. ISL6745EVAL2Z Offline High Brightness White LED Driver With High Power Factor for Universal Input, Intersil Corporation application note: AN1411 4. Z. Ye, et al, “Design Considerations of a High Power Factor SEPIC Converter for High Brightness White LED Lighting Applications,” IEEE PESC conference record, 2008, June 2008, Greece, pp 2657- 2663. FIGURE 25. OVERSHOT OF LED CURRENT (400mA, 22%) 7 AN1487.0 July 28, 2009 Schematic With/Without Triac Dimming Compatible 8 Application Note 1487 AN1487.0 July 28, 2009 Application Note 1487 TABLE 5. ISL6745ALEVAL3Z NON-ISOLATED LED ADAPTOR WITHOUT TRIAC DIMMING VALUE NO. PACKAGE TOL VOLTAGE (V) NO. QTY. REFERENCE VALUE 1 1 CR1 2A BRIDGE RECTIFIER 400 DIODES 2W04G 2 1 CR2 3A SMC 600 DIODES RS3J-E3 3 1 CR3 BAT54C SOT23 DIODES 4 1 CR4 BAT54 SOT23 DIODES 5 2 C1, C2 0.1µF X2-CAP 250 PANASONIC ECQU2A 104ML 6 1 C3 22nF SM1812 250 TDK C453C0G2E223J 7 1 C4 47nF SM1812 250 TDK C453C0G2E223J 8 1 C5 DNP SM1210 100 MURATA 9 1 C6 2.2µF SM0603 MURATA GRM31CR71H225K 10 2 C7, C27 47µF SM1210 MURATA GRM32ER61C476ME15L 11 2 C8, C9 1800µF CHEMI CON EKZE250ELL182MK30S 12 3 C10, C24, C29 0.1µF SM0603 13 1 C12 220nF SM0603 14 1 C13 470nF SM0603 15 1 C15 10nF SM0603 16 2 C16, C20 6.8µF SM0805 17 1 C17 220pF SM0603 18 1 C18 470pF SM0603 19 2 C19, C20 220nF SM0603 20 1 C21 DNP 21 1 C23 220nF SM0805 22 2 C25, C28 1.2nF SM0603 23 1 F1 0.5A FUSE 24 1 L1 330µF 25 1 L2 390µF 26 1 L3 39µF 27 5 28 1 Q0 1A 29 1 Q1 30 2 31 12.5x20mm :220n 25 VENDOR PART NO. NPO/C0G SM0603 25 TR5 COILCRAFT MSS1278-334KLB 500 COILCRAFT MSD1278-334KLB 650 PULSE PA2050.393NL KEYSTONE 1514-2 DPAK FAIRCHILD FQD1N50TM 3.2A DPAK INFINEON IPD60R385CP Q3, Q5 BSS138 SOT23 3 R1, R2, R6 1.0M SM1206 5% 32 2 R3, R7 0Ω RES-2W 5% 33 1 R4 100Ω SM1206 5% 34 2 R8, R9 100kΩ SM1206 1% 35 1 R10 14.3kΩ SM0603 1% 36 1 R11 100Ω SM0603 5% 37 1 R12 0.05Ω SM2512 5% 38 1 R13 10Ω SM0805 5% 39 1 R14 499Ω SM1206 5% P1, P2, P3, P4, P5 TERMINAL 9 AN1487.0 July 28, 2009 Application Note 1487 TABLE 5. ISL6745ALEVAL3Z NON-ISOLATED LED ADAPTOR WITHOUT TRIAC DIMMING (Continued) NO. QTY. REFERENCE VALUE 40 1 R15 41 1 42 VALUE NO. VOLTAGE (V) PACKAGE TOL 51.1Ω SM0805 5% R16 DNP SM1206 5% 1 R17 0.18Ω SM1206 1% 43 1 R18 3.01MΩ SM0603 5% 44 1 R19 2kΩ SM0603 5% 45 1 R21 10kΩ SM0603 5% 46 1 R22 1kΩ SM1206 5% 47 6 R23, R24, R27, R28, R31, R32 10.0kΩ SM0603 1% 48 1 R25 14.0kΩ SM0603 1% 49 1 R26 30.1kΩ SM0603 1% 50 1 R29 59.0kΩ SM0603 1% 51 1 R32 150kΩ SM0603 5% 52 1 R33 61.9kΩ SM0603 5% 53 1 R34 196kΩ SM0603 1% 54 1 R39 1.0kΩ SM0603 5% 55 1 U1 ISL6745A MSOP10 INTERSIL ISL6745AAU 56 1 U3 EL5420 TSSOP14 INTERSIL EL5420CRZ 57 1 VR1 11V SOT23 DIODES BZX84C11 58 1 VR2 24V SOT23 VISHAY MMBZ5252 59 1 VR3 5.1V SOT23 DIODES BZX84B5V1LT1 60 1 VR4 DNP SOT23 DIODES BZX84C18 61 1 Z1 - - 10 VENDOR PART NO. LITTELFUSE TMOV14R140E AN1487.0 July 28, 2009 Application Note 1487 TABLE 6. ISL6745ALEVAL3Z NON-ISOLATED LED ADAPTOR WITH TRIAC DIMMING VALUE NO. PACKAGE TOL VOLTAGE (V) NO. QTY. REFERENCE VALUE 1 1 CR1 2A 2 1 CR2 3A SMC 3 1 CR3 BAT54C SOT23 DIODES 4 1 CR4 BAT54 SOT23 DIODES 5 2 C1, C2 0.1µF X2-CAP 250 PANASONIC ECQU2A 104ML 6 1 C3 22nF SM1812 250 TDK C453C0G2E223J 7 1 C4 47nF SM1812 250 TDK C453C0G2E223J 8 1 C5 DNP SM1210 100 MURATA 9 1 C6 2.2µF SM0603 MURATA GRM31CR71H225K 10 2 C7, C27 47µF SM1210 MURATA GRM32ER61C476ME15L 11 2 C8, C9 1800µF 12.5x20mm CHEMI CON EKZE250ELL182MK30S 12 3 C10, C24, C29 0.1µF SM0603 13 1 C12 220nF SM0603 14 1 C13 470nF SM0603 15 1 C15 10nF SM0603 16 2 C16, C20 6.8µF SM0805 17 1 C17 220pF SM0603 18 1 C18 470pF SM0603 19 2 C19, C20 220nF SM0603 20 1 C21 DNP 21 1 C23 220nF SM0805 22 2 C25, C28 1.2nF SM0603 23 1 F1 0.5A FUSE 24 1 L1 330µH 25 1 L2 390µH 26 1 L3 39µH 27 5 P1, P2, P3, P4, P5 TERMINAL 28 1 Q0 1A 29 1 Q1 30 2 31 BRIDGE RECTIFIER :220n VENDOR PART NO. 400 DIODES 2W04G 600 DIODES RS3J-E3 25 NPO/C0G SM0603 25 TR5 COILCRAFT MSS1278-334KLB 500 COILCRAFT MSD1278-334KLB 650 PULSE PA2050.393NL KEYSTONE 1514-2 DPAK FAIRCHILD FQD1N50TM 3.2A DPAK INFINEON IPD60R385CP Q3, Q5 BSS138 SOT23 3 R1, R2, R6 1.0MΩ SM1206 5% 32 2 R3, R7 36Ω RES-2W 5% 33 1 R4 0Ω SM1206 5% 34 2 R8, R9 100kΩ SM1206 1% 35 1 R10 14.3kΩ SM0603 1% 36 1 R11 100Ω SM0603 5% 37 1 R12 0.05Ω SM2512 5% 38 1 R13 10Ω SM0805 5% 39 1 R14 499Ω SM1206 5% 11 AN1487.0 July 28, 2009 Application Note 1487 TABLE 6. ISL6745ALEVAL3Z NON-ISOLATED LED ADAPTOR WITH TRIAC DIMMING (Continued) NO. QTY. REFERENCE VALUE 40 1 R15 41 1 42 VALUE NO. VOLTAGE (V) PACKAGE TOL VENDOR PART NO. 51.1Ω SM0805 5% R16 DNP SM1206 5% 1 R17 0.18Ω SM1206 1% 43 1 R18 3.01MΩ SM0603 5% 44 1 R19 2kΩ SM0603 5% 45 1 R21 10kΩ SM0603 5% 46 1 R22 1kΩ SM1206 5% 47 6 R23, R24, R27, R28, R31, R32 10.0kΩ SM0603 1% 48 1 R25 14.0kΩ SM0603 1% 49 1 R26 30.1kΩ SM0603 1% 50 1 R29 59.0kΩ SM0603 1% 51 1 R32 150kΩ SM0603 5% 52 1 R33 61.9kΩ SM0603 5% 53 1 R34 196kΩ SM0603 1% 54 1 R39 1.0kΩ SM0603 5% 55 1 U1 ISL6745A MSOP10 INTERSIL ISL6745AAU 56 1 U3 EL5420 TSSOP14 INTERSIL EL5420CRZ 57 1 VR1 11V SOT23 DIODES BZX84C11 58 1 VR2 24V SOT23 VISHAY MMBZ5252 59 1 VR3 5.1V SOT23 DIODES BZX84B5V1LT1 60 1 VR4 DNP SOT23 DIODES BZX84C18 61 1 Z1 - - LITTELFUSE TMOV14R140E Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 12 AN1487.0 July 28, 2009