DN05079/D Design Note – DN05079/D Direct-AC, Linear LED Driver Topology: CCR Straight Circuit (120 VAC & 230 VAC) Device Application Topology Efficiency Input Power Power Factor NSIC20x0JB AC LED Lighting Direct AC, Linear 68 – 84 % Variable 6 – 14 W 0.92 – 0.97 THD 20 – 39%, Variable Figure 1 – General “Straight Circuit” CCR-based LED Driver Schematic performance, which will be referred to and supported by this note. Overview This document presents a simple, low-cost LED driver topology useful for AC LED lighting solutions at any mains voltage or frequency. This costeffective driver design combines good power factor, simplicity, high efficiency, and impressive driver scalability in a very adaptive and versatile platform solution. The circuit is designed for use within a wide input voltage range, and can be made to operate anywhere between 90 VAC and 300 VAC. The driver works best when optimized for a specific supply voltage range (such as 100 – 130 VAC or 190 – 250 VAC), which may influence LED load design. The circuit employs ON Semiconductor Constant Current Regulators (CCRs) to regulate LED current and protect LEDs from over-voltage conditions. This driver is extremely scalable, and can support many modular extensions for circuit tuning and August 2015, Rev. 0 The driver traditionally drives a single LED load, which may be composed of multi-junction highvoltage (HV) LEDs or multiple standard low-voltage LEDs. The “LED String” may flexibly represent a high-voltage string of multiple LEDs, or a single COB LED. The LED load will need to be appropriately designed for CCR over-voltage considerations, and this note will discuss conditions and refer to protection techniques. The circuit is protected from mains transients by a fuse and metal-oxide varistor. The driver can also accommodate EMI filtering techniques. This technical note will first overview general behaviors of the circuit, identify design-dependent performance parameters, and then finish off with a closer examination of six specific designs. www.onsemi.com 1 DN05079/D Key Features • • • • • • • • • • Wide input voltage range. High-voltage transient and tolerance protection. Simple, low-cost implementation. Simple and flexible load design, highly compatible with COB implementations. High power factor across voltage range. Modular design flexibility, can accommodate many functions (EMI filter, OVP, etc.) Compatible with most phase-cut dimmers. Adjustable for different LED voltages. Scalable for different currents/power levels. Predictable electrical performance Circuit Description The circuit consists of, at a minimum, a full-wave bridge rectifier (D1 – D4), a current regulator (“CCR”), and an LED load (represented by “LED String”) connected in series, as shown in Figure 1. Other more specific schematics are shown later on in Figures 3, 11-16. For high-voltage (220 VAC and above) or low load voltage (see Fig. 10) an OVP block is recommended, which as described by Figure 2 and shown in Figure 3b, consists of a threshold detector (R1 – R2, Q1), pass transistor network (Q2, R3), and power resistor (R4). Circuit Operation and Design The bridge rectifier outputs a half-wave sine peaking at about 170 V for 120 VAC, and about 320 V for 230 VAC. This bridge output is referenced between the cathodes of D2 and D4 to the anodes of D1 and D3. The circuit drives the LED load directly off of the output of the bridge voltage, hence the name “directAC.” The driver’s design philosophy is to achieve maximum simplicity with minimum component count. For a more streamlined approach, this note will only overview OVP schemes in particular cases. August 2015, Rev. 0 The driver’s operation is very simple to understand. As a linear driver, the CCR requires a voltage drop to perform regulation (typ. 1.8 V minimum), and for the LEDs to turn on, there must be sufficient voltage provided by the bridge. Therefore, the combination of these two conditions means that light will only be produced when the bridge voltage is above the LEDs and minimum CCR voltage combined. 𝐸𝐸. 1) 𝐵𝐵𝐵𝐵𝐵𝐵 ≥ 1.8 𝑉𝐴𝐴 + 𝐿𝐿𝐿 𝑉𝑓 As the LEDs will turn on with high voltage, they must turn off with low voltage. This lends the driver a “duty cycle”-like effect, determined by the magnitude of the LED load voltage. Furthermore, standard phase-cut dimming modifies the phase length of this duty cycle, emulating PWM-like behavior and avoiding the nonlinear light creation of current modulation. Whether dimming or not, this duty-cycle behavior inherently increases LED lifetime and reliability. When the LEDs are on, the remaining voltage is dropped on the CCR or current regulator, which in most cases, directly connects the bridge and LEDs, as implied in Eq. 2 below. 𝐸𝐸. 2) 𝑉𝑏𝑏𝑏𝑏𝑏𝑏 (𝑡) = 𝑉𝐶𝐶𝐶 (𝑡) + 𝑉𝑓 This is the source of most of the power lost in a straight circuit driver topology, as there will inherently be a mismatch between the varying sine-wave bridge voltage waveform and the DC-like LED load, the difference yielding power dissipation on the CCR. This effect becomes more exaggerated as the LED load voltage decreases, or the supply voltage increases. Figures 8 and 9 and Table 9 together illustrate this characteristic. If at any time the CCR is at risk of over-voltage conditions (the maximum possible VCCR,PK is above the maximum voltage rating), then special OVP protection circuitry will need to be deployed to ensure reliable operation, which will be discussed in the next section. www.onsemi.com 2 DN05079/D Figure 2 – General “Straight Circuit” CCR-based LED driver block diagram with OVP functionality. With High-Voltage Protection Circuitry VOVP(Q1) = 101 V. This would be an appropriate protection level for a 120 V CCR. If the driver is at risk of an over-voltage scenario, then additional circuitry will be necessary to monitor the CCR VAK and take protective measures when necessary. The general condition for over-voltage protection necessity is given by Eq. 3. 𝐸𝐸. 3) 𝑉𝐴𝐴,𝑚𝑚𝑚 > 𝑉𝐼𝐼,𝑚𝑚𝑚,𝑅𝑅𝑅 ⋅ √2 − 𝑉𝐹,𝑙𝑙𝑙𝑙 An adequately protected circuit is shown in Figure 3b, taken from the AND9179/D application note, which overviews many other different types of over-voltage protection not covered in this technical note. The protection circuit used in these 230 VAC designs roughly measures the VAK across CCR1. As a highvoltage threshold detector, Q1 controls whether current passes through a transistor (Q2), or a highvoltage power resistor (R4). When the VAK threshold set by the designer is surpassed (according to Eq. 4 below), Q2 turns off, and the power resistor R4 takes on some of the voltage drop from the CCR, according to Ohm’s Law. If properly designed, the R4 resistor momentarily reduces the VAK on the CCR, allowing higher input voltages to be tolerated without exceeding device voltage ratings. 𝐸𝐸. 4) 𝑉𝑂𝑂𝑂(𝑄1) = 𝑉𝐵𝐵(𝑠𝑠𝑠) ⋅ 𝑅1 + 𝑅2 𝑅2 Let’s consider a design example protecting a 120 V, 30 mA CCR, such as the NSIC2030JBT3G. To provide sufficient margin below the device rating, let’s design the OVP to activate around 100 V. When using an MMBT3904L (expected VBE(sat) of 0.68 V at 25 °C) as Q1 to trigger the OVP, Eq. 4 yields resistor values R1 = 1 MΩ and R2 = 6.8 kΩ to produce August 2015, Rev. 0 As mentioned earlier, the power resistor R4 (as shown in Figure 3b), needs to be carefully considered so as to best protect its companion CCR network. Thankfully, only Ohm’s Law must be considered: the desired voltage drop on the resistor divided by total instantaneous CCR current yields the proper resistor value, as shown in Eq. 5. Bear in mind that the desired resistor voltage drop must be less than the voltage that the OVP triggers at, so that the CCR remains in full regulation during the transition. For additional support, see Eq. 6 of application note AND9179/D. 𝐸𝐸. 5) 𝑉𝐷𝐷𝐷𝐷,𝑅4 = 𝐼𝐶𝐶𝐶,𝑚𝑚𝑚 ⋅ 𝑅4 It follows that the Q2 device ratings are determined by the maximum instantaneous CCR current (ICCR,max), as well as the expected voltage drop on the R4 resistor (VDROP,R4). R3 should be selected as to provide sufficient base current for the Q2 transistor. It should be noted that this over-voltage protection scheme does not degrade the quality or amount of light produced—it only saves the LED driver when the VAK approaches unsafe levels, as determined by the designer. The output power over the LEDs is maintained when using a VAK-sensitive scheme like this, although the driver’s increased voltage drop means that circuit efficiency is reduced at high voltages. Although only one design is featured in this note, many different OVP techniques and circuit schematics are reviewed further in the application notes AND9179/D and AND9203/D. www.onsemi.com 3 DN05079/D Practical implementations of the circuits represented by Figures 1 and 2 (with and without OVP) are shown here with waveforms for quick, conceptual reference, in accordance with the designators used above. All the specific designs reviewed in this design note will be one of these two templates below. Figure 3: General straight circuit implementations for any mains voltage, shown a) without OVP, and b) with OVP. General Waveforms Below are screenshots demonstrating waveforms of generic straight circuit performance, with and without OVP. The first three screenshots (Fig. 4 – 6) are from a 120 VAC driver utilizing a 120 VF LED load and 50mA CCR. The fourth screenshot (Fig. 7) is a 230 VAC driver utilizing a 180 VF LED load and 20 mA CCR. The OVP is implemented on only 230 VAC designs, and not on 120 VAC designs in this note, though OVP is not necessarily exclusive to high line voltages. This necessity is conditional on the relationship between the supply and load voltage levels (see Eq. 2, Fig. 10). Figure 4 – The total input current follows the voltage waveform very closely, yielding high power factor and good THD performance. LED current is the supply current after rectification. August 2015, Rev. 0 www.onsemi.com 4 DN05079/D Figure 5 – A simple photodetector circuit using a NOA1212 was used to generate a waveform of the LED light output for flicker index measurements in this design note. Efficacy and light intensity vary by LED, but the general waveform shape and linear current-light relationship are maintained. Figure 6 – Output voltage and LED current waveforms indicate no flicker when used with TRIAC dimming shown in the maximum position. This particular dimmer sports a non-zero output filter voltage during the “off” state, but the circuit receives little-to-no input current when the TRIAC is off, and the current is normal when the TRIAC is on. August 2015, Rev. 0 www.onsemi.com 5 DN05079/D Figure 7 – With the over-voltage protection circuitry, the circuit monitors and throttles the peak voltages exercised on the CCR. In this case, we use a resistor to drop excess voltage to prevent damaging the CCR. Output current remains roughly constant while LEDs are on. Design Dependencies and Tradeoffs Many of the electrical and optical performance characteristics of this driver are dependent on the relationship of the LED load voltage and application voltage range. The simplicity of the straight circuit makes many factors mathematically predictable, lending incredible insight into the design process. For the figures below, LED load voltage has been normalized to the peak line voltage, so as to provide the most generalized analysis. As seen in Figures 8 and 9 below, input power, efficiency, and thermals improve with high load voltages, whereas many other characteristics, including power factor, THD, and dimming performance improve with lower load voltages. It is the careful balancing of these trends that yields a successful design. Figure 8 below illustrates a few trends that are mathematically predictable, and are determined based upon the behavior of a sine wave compared to a DC level. Figure 8 may be loosely referenced during the design phase when considering very critical parameters, such as efficiency, total current, and power estimation. Figure 9 displays empirically validated trends on a graph as a function of LED voltage, normalized to the bridge voltage peak. August 2015, Rev. 0 The “Decreasing VF” and Increasing VAC” scenarios described in Table 1 generally correspond to a shift to the left-ward shift on the Fig. 8 and 9 plots, whereas the “Increasing VF” and “Decreasing VAC” trends correspond to an increase in normalized forward voltage, and shift the plot point to the right. These mathematical models neglect circuit and environmental effects on LED forward voltage, such as VF decrease due to self-heating and rising ambient temperature range, or VF increase due to ohmic behavior in the LEDs while increasing current. Generally, these parameters change, driver performance can be expected to move up and down these curves. Figure 10 provides a rough graphical characteristic displaying “critical LED load voltage” as a function of input RMS voltage. The critical LED load voltage, in this case, is a condition for the load voltage below which some protective circuitry will be required for CCR reliability. When LED voltages are low, CCRs experience high peak voltages, and care must be taken so as not to surpass voltage breakdown levels. The plot given in Figure 10 incorporates a 10 V margin on the CCR’s maximum voltage. The equation determining the boundary condition for critical LED load voltage is given in Eq. 3. www.onsemi.com 6 DN05079/D Predictive Performance vs. LED Load Voltage Normalized to Peak Bridge Voltage Conduction Time, Efficiency, % of Pmax/Ireg (Percent, %) Conduction Time (%) Efficiency (%) % of Pmax 0.2 0.4 Irms (% of Ireg) Pout ( % of Pdc = Vf*Ireg) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 0.0 0.1 0.3 0.5 0.6 0.7 0.8 Normalized Forward Voltage (Vf/Vbridge,max) 0.9 1.0 Figure 8: Certain parameters useful in predicting driver performance are mathematically dependent on VF. Measured Performance v. LED Load Voltage Normalized to Peak Bridge Voltage Meas. Efficiency (%) THD (%) PF Min Dimming Level 1 90% 0.9 80% 0.8 70% 0.7 60% 0.6 50% 0.5 40% 0.4 30% 0.3 20% 0.2 10% 0.1 Power Factor Efficiency, THD, Minimum Dimming Level, % DC Efficacy (Percent, %) % of DC Efficacy 100% 0 0% 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Normalized Forward Voltage (VF/VPk) Figure 9: While not necessarily formulaic, real trends of critical performance parameters exist across VF. August 2015, Rev. 0 www.onsemi.com 7 DN05079/D Performance Decreasing VF Increasing VF Decreasing VAC Increasing VAC IRMS(IN) (mA) Small Increase Small Decrease Decrease Increase PF Small Increase Small Decrease Small Decrease Small Increase THD (IRMS, %) Decrease Increase Increase Decrease PIN (W) Increase Decrease Decrease Increase POUT (W) Non-linear Non-linear Non-linear Non-linear Efficiency (%) Decrease Increase Increase Decrease Min. Dimming Level (%) Decrease Increase No effect No effect Effective Duty Cycle (%) Increase Decrease Decrease Increase Flicker Index Decrease Increase Increase Decrease CCR Temperature (°C) Increase Decrease Decrease Increase Table 1 – General trends for the circuit shown in Figure 1. Preferred/improved results indicated in shaded boxes. Critical Load Voltage v. AC Mains Voltage Straight Circuit Topologies, 10 V Margin Using 120 V CCR 450 Using 45/50 V CCR Critical LED Load Voltage (V) 400 VIN = 305, VLED = 396 VIN = 277, VLED = 357 350 VIN = 305, VLED = 321 VIN = 240, VLED = 304 300 VIN = 277, VLED = 282 VIN = 220, VLED = 276 250 VIN = 240, VLED = 229 VIN = 220, VLED = 201 200 VIN = 132, VLED = 152 VIN = 120, VLED = 135 VIN = 108, VLED = 118 150 100 VIN = 90, VLED = 92 VIN = 132, VLED = 77 VIN = 120, VLED = 60 VIN = 108, VLED = 43 50 VIN = 90, VLED = 17 0 0 50 100 150 200 AC Line Voltage (RMS) 250 300 350 Figure 10: Below the critical LED load voltage, protective circuitry will be needed to keep CCRs within their safe operating regions. The figure above incorporates a 10 V margin from the maximum CCR voltage rating. Source equation is given by Eq. 3 in this technical note. August 2015, Rev. 0 www.onsemi.com 8 DN05079/D Case 1: 6 W, 120 VAC Driver Design Case 1 is a driver design of about 6 W input power, intended for 120 VAC mains. This design does not employ any OVP on the CCR. Depending on the load design, this may be acceptable—use Eq. 3 to determine if OVP is necessary on this circuit. If so, refer to the design in “Case 4” for further guidance. Figure 11 – Schematic of straight circuit without over-voltage protection (OVP). Bill of Materials Designator Manufacturer Part No. Qty Description Value Tolerance CCR1 ON Semi NSIC2050JB 1 Constant Current Regulator 120 V, 50 mA ±15% CCR2 F1 MOV1 D1 – D4 LED ON Semi Any Any ON Semi Any NSIC2030JB MRA4004 - 1 1 1 4 * Constant Current Regulator Fuse Varistor Diode Light-Emitting Diode 120 V, 30 mA 200 V, 1 A 150 VAC 400 V, 1 A 120 V, 90 mA ±15% - * The LED bank design may be composed of a few COB implementations or many single-junction 3V LEDs. Table 2 – Bill of materials for the circuit shown in Figure 11. Circuit Data 108 VAC 114 VAC 120 VAC 126 VAC 132 VAC IRMS(IN) (mARMS) PF THD (IRMS, %) PIN (W) POUT (W) Efficiency (%) 58.33 0.9296 39.5 % 5.88 W 4.74 W 80.6 % 58.67 0.9421 35.5 % 6.33 W 4.89 W 77.2 % 57.99 0.9521 32.0 % 6.65 W 4.91 W 73.7 % 57.67 0.9589 29.6 % 6.99 W 4.98 W 71.2 % 57.09 0.9649 27.3 % 7.28 W 4.990 W 68.5 % Min. Dimming Level (%) Effective Duty Cycle (%) Flicker Index 3.9 % 50.8 % 0.464 3.7 % 54.1 % 0.434 3.8 % 57.0 % 0.411 3.8 % 59.5 % 0.388 3.8 % 61.6 % 0.373 Table 3 – Electrical characteristics for the circuit shown in Figure 11. August 2015, Rev. 0 www.onsemi.com 9 DN05079/D Case 2: 10 W, 120 VAC Driver Design Case 2 is a driver design of about 10 W input power, intended for 120 VAC mains. This design does not employ any OVP for the CCR. Depending on the load design, this may be acceptable—use Eq. 3 to determine if OVP is necessary on this circuit. If so, refer to Case 4 for further guidance. Figure 12 – Schematic of straight circuit without over-voltage protection (OVP). Bill of Materials Designator Manufacturer Part No. Qty Description Value Tolerance CCR1 – 2 CCR3 F1 MOV1 D1 – D4 LED ON Semi ON Semi Any Any ON Semi Any NSIC2050JB NSIC2030JB MRA4004 - 2 1 1 1 4 * Constant Current Regulator Constant Current Regulator Fuse Varistor Diode Light-Emitting Diode 120 V, 50 mA 120 V, 30 mA 200 V, 1 A 150 VAC 400 V, 1 A 120 V, 130 mA ±15% ±15% - * The LED bank design may be composed of a few COB implementations or many single-junction 3V LEDs. Table 4 – Bill of materials for the circuit shown in Figure 12. Circuit Data 108 VAC 114 VAC 120 VAC 126 VAC 132 VAC IRMS(IN) (mA) 93.37 94.16 93.13 92.65 91.81 PF THD (IRMS, %) PIN (W) POUT (W) Efficiency (%) Min. Dimming Level (%) 0.9298 39.40 9.391 7.887 84.0 2.8 % 0.9424 35.33 10.122 8.156 80.6 2.8% 0.9533 31.57 10.704 8.107 75.7 2.4 % 0.9603 28.96 11.220 8.239 73.4 2.8% 0.9657 26.80 11.716 8.293 70.8 2.9 % Effective Duty Cycle (%) Flicker Index 51.23 0.46 53.36 0.43 56.69 0.41 59.90 0.38 62.15 0.37 Table 5 – Electrical characteristics for the circuit shown in Figure 12. August 2015, Rev. 0 www.onsemi.com 10 DN05079/D Case 3: 14 W, 120 VAC Driver Design Case 3 is a driver design with roughly 14 W nominal input power, intended for 120 VAC mains. This design does not employ any OVP on the CCR. Depending on the load design, this may be acceptable—use Eq. 3 to determine if OVP is necessary on this circuit. If so, refer to Case 4 for further guidance. Figure 13 – Schematic of straight circuit without over-voltage protection (OVP). Bill of Materials Designator Manufacturer Part No. Qty Description Value Tolerance CCR1 – 3 CCR4 F1 MOV1 D1 – D4 LED ON Semi ON Semi Any Any ON Semi Any NSIC2050JB NSIC2030JB MRA4004 - 3 1 1 1 4 * Constant Current Regulator Constant Current Regulator Fuse Varistor Diode Light-Emitting Diode 120 V, 50 mA 120 V, 30 mA 200 V, 1 A 150 VAC 400 V, 1 A 120 V, 180 mA ±15% ±15% - * The LED bank design may be composed of a few COB implementations or many single-junction 3V LEDs. Table 6 – Bill of materials for the circuit shown in Figure 13. Circuit Data 108 VAC 114 VAC 120 VAC 126 VAC 132 VAC IRMS(IN) (mA) 124.20 124.95 124.30 122.72 120.77 PF THD (IRMS, %) PIN (W) POUT (W) Efficiency (%) Min. Dimming Level (%) 0.924 41.3 % 12.49 W 10.33 W 82.7 % 2.6 % 0.9381 36.8 % 13.36 W 10.62 W 79.4 % 2.5 % 0.949 33.2 % 14.13 W 10.76 W 76.2 % 2.4 % 0.9567 30.32 % 14.787 W 10.768 W 72.8 % 2.4 % 0.9628 27.95 15.324 10.734 70.0 % 2.4 % Effective Duty Cycle (%) Flicker Index 49.97 % 0.47 53.53 % 0.44 55.18 % 0.42 58.10 % 0.39 61.10 % 0.38 Table 7 – Electrical characteristics for the circuit shown in Figure 13. August 2015, Rev. 0 www.onsemi.com 11 DN05079/D Case 4: 6 W, 230 VAC Driver Design Case 4 is a driver design of about 6 W input power, intended for 220 – 240 VAC mains. This driver design employs OVP to safely interface the LEDs and CCRs with high line voltages. Depending on the load design, this may or may not be needed—use Eq. 3 to determine if OVP is necessary when driving any LED load. Figure 14 – Schematic of straight circuit LED driver with over-voltage protection (OVP). Bill of Materials Designator Manufacturer Part No. Qty Description Value Tolerance CCR1 R1 R2 R3 R4 Q1 Q2 F1 MOV1 D1 – D4 LED ON Semi Any Any Any Any ON Semi ON Semi Any Any ON Semi Any NSIC2030JB MMBT3904L NSS1C201L MRA4007 - 1 1 1 1 1* 1 1 1 1 4 ** Constant Current Regulator Resistor Resistor Resistor Resistor NPN Transistor Low VCE,Sat NPN Transistor Fuse Varistor Diode Light-Emitting Diode 120 V, 20 mA 1 MΩ, 1/8 W 6.8 kΩ, 1/8 W 100 kΩ, 1/8 W 3.0 kΩ, ½ W 40 V, 100 mA 100 V, 2.0 A 200 V, 1 A 300 VAC 1000 V, 1 A 120 V, 20 mA ± 15% ± 1% ± 1% ± 10% ± 5% - * The power resistor may be a single resistor or multiple series/parallel components to optimize cost, space, etc. ** The LED bank design may be composed of a few COBs or many single-junction 3V LEDs. Table 8 – Bill of materials for the circuit shown in Figure 14. Circuit Data IRMS(IN) (mA) PF THD (IRMS, %) PIN (W) POUT (W) Efficiency (%) Effective Duty Cycle (%) Flicker Index 190 VAC 220 VAC 240 VAC 264 VAC 277 VAC 25.61 0.946 34.4 % 4.616 W 3.366 W 72.9 % 54.7 % 0.42 27.42 0.961 28.4 % 5.82 W 4.569 W 78.6 % 62.7 % 0.36 28.25 0.967 26.1 % 6.57 W 5.32 W 80.9 % 66.1 % 0.33 28.56 0.975 22.6 % 7.36 W 5.68 W 77.2 % 69.4 % 0.29 28.43 0.978 20.9 7.71 W 5.75 W 74.6 71.0 % 0.28 Table 9 – Electrical characteristics for the circuit shown in Figure 14. August 2015, Rev. 0 www.onsemi.com 12 DN05079/D Case 5: 10 W, 230 VAC Driver Design Case 1 is a driver design of about 10 W input power, intended for 220 – 240 VAC mains. This design employs a simple OVP scheme to protect the CCR. Depending on the load design, this may not be needed—use Eq. 3 to determine if OVP is necessary on this circuit. Figure 15 – Schematic of straight circuit with over-voltage protection (OVP). Bill of Materials Designator Manufacturer Part No. Qty Description Value Tolerance CCR1 – 2 R1 R2 R3 R4 Q1 Q2 F1 MOV1 D1 – D4 LED ON Semi Any Any Any Any ON Semi ON Semi Any Any ON Semi Any NSIC2030JB MMBT3904L NSS1C201L MRA4007 - 2 1 1 1 1* 1 1 1 1 4 ** Constant Current Regulator Resistor Resistor Resistor Resistor NPN Transistor Low VCE,Sat NPN Transistor Fuse Varistor Diode Light-Emitting Diode 120 V, 30 mA 1 MΩ, 1/8 W 6.8 kΩ, 1/8 W 100 kΩ, 1/8 W 1.5 kΩ, 1 W 40 V, 100 mA 100 V, 2.0 A 200 V, 1 A 300 VAC 1000 V, 1 A 120 V, 60 mA ± 15% ± 1% ± 1% ± 10% ± 5% - * The power resistor may be a single resistor or multiple series/parallel components to optimize cost, space, etc. ** The LED bank design may be composed of a few COBs or many single-junction 3V LEDs. Table 10 – Bill of materials for the circuit shown in Figure 14. Circuit Data IRMS(IN) (mA) PF THD (IRMS, %) PIN (W) POUT (W) Efficiency (%) Effective Duty Cycle (%) Flicker Index 190 VAC 220 VAC 240 VAC 264 VAC 277 VAC 49.57 0.941 35.8 % 8.88 W 6.73 75.8 % 53.8 % 0.4104 52.78 0.959 29.5 % 11.1 W 9.10 W 82.0 % 61.9 % 0.3480 53.79 0.968 25.9 % 12.53 W 9.96 W 79.5 % 65.9 % 0.3190 53.90 0.976 22.4 % 13.89 W 10.46 W 75.3 % 69.0 % 0.2889 53.26 0.979 20.9 % 14.44 W 10.48 W 72.6 % 70.8 % 0.2763 Table 11 – Electrical characteristics for the circuit shown in Figure 15. August 2015, Rev. 0 www.onsemi.com 13 DN05079/D Case 6: 14 W, 230 VAC Driver Design Case 6 is a driver design of about 14 W input power, intended for 220 – 240 VAC mains. This design employs a simple OVP scheme to protect the CCR. Depending on the load design, this may not be needed—use Eq. 3 to determine if OVP is needed on this circuit. Figure 16 – Schematic of straight circuit with over-voltage protection (OVP). Bill of Materials Designator Manufacturer Part No. Qty Description Value Tolerance CCR1 – 2 R1 R2 R3 R4 Q1 Q2 F1 MOV1 D1 – D4 LED ON Semi Any Any Any Any ON Semi ON Semi Any Any ON Semi Any NSIC2050JB MMBT3904L NSS1C201L MRA4007 - 2 1 1 1 1* 1 1 1 1 4 ** Constant Current Regulator Resistor Resistor Resistor Resistor NPN Transistor Low VCE,Sat NPN Transistor Fuse Varistor Diode Light-Emitting Diode 120 V, 50 mA 1 MΩ, 1/8 W 6.8 kΩ, 1/8 W 100 kΩ, 1/8 W 910 Ω, ½ W 40 V, 100 mA 100 V, 2.0 A 200 V, 1 A 300 VAC 1000 V, 1 A 120 V, 100 mA ± 15% ± 1% ± 1% ± 10% ± 5% - * The power resistor may be a single resistor or multiple series/parallel components to optimize cost, space, etc. ** The LED bank design may be composed of a few COBs or many single-junction 3V LEDs. Table 12 – Bill of materials for the circuit shown in Figure 14. Circuit Data IRMS(IN) (mA) PF THD (IRMS, %) PIN (W) POUT (W) Efficiency (%) Effective Duty Cycle (%) Flicker Index 190 VAC 220 VAC 240 VAC 264 VAC 277 VAC 59.01 0.942 35.7 % 10.59 W 8.06 W 76.2 % 54.4 % 0.4276 62.73 0.960 29.0 % 13.29 W 10.68 W 80.4 % 61.7 % 0.3445 62.67 0.969 25.4 % 14.60 W 11.40 W 78.1 % 65.6 % 0.3107 61.06 0.976 22.2 % 15.74 W 11.53 W 73.3 % 68.8 % 0.2831 59.33 0.979 20.6 % 16.07 W 11.32 W 70.4 % 70.4 % 0.2712 Table 13 – Electrical characteristics for the circuit shown in Figure 16. August 2015, Rev. 0 www.onsemi.com 14 DN05079/D Further Reference For similar designs and related material, see the following ON Semiconductor technical publications. • Design Note – DN05013/D: Simple ENERGY STAR ® Compliant LED Driver Retrofit in a T5 Tube using 160mA CCR http://www.onsemi.com/pub_link/Collateral/DN05013-D.PDF • Application Note – AND9179/D: In-Driver High Voltage Protection Techniques for Constant Current Regulators http://www.onsemi.com/pub_link/Collateral/AND9179-D.PDF • Application Note – AND9203/D: Optimizing CCR Protection for Minimal Part Count http://www.onsemi.com/pub_link/Collateral/AND9203-D.PDF © 2015 ON Semiconductor. Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its products at any time, without notice. Design note created by Travis Alexander, e-mail: [email protected] August 2015, Rev. 0 www.onsemi.com 15