NCP3065SOBCKGEVB

NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB High Intensity LED Drivers Using NCP3065/NCV3065 Evaluation Board User's Manual Introduction http://onsemi.com EVAL BOARD USER’S MANUAL High brightness LEDs are a prominent source of light and have better efficiency and reliability than conventional light sources. Improvements in high brightness LEDs present the potential for creative new lighting solutions that offer an improved lighting experience while reducing energy demand. LEDs require constant current driver solutions due to their wide forward voltage variation and steep V/I transfer function. For applications that are powered from low voltage AC sources typically used in landscape lighting or low voltage DC sources that may be used in automotive applications, high efficiency driver that can operate over wide range of input voltages to drive series strings of one to several LEDs. Figure 1. NCP3065 3A Buck Evaluation Board Figure 2. NCP3065 Buck Evaluation Board NCP3065/NCV3065 EVALUATION BOARD NCP3065/NCV3065 can operate as a switcher or as a controller. These options are shown bellow. The brightness of the LEDs or light intensity is measured in Lumens and is proportional to the forward current flowing through the LED. The light efficiency can vary with the current flowing through the LED string. The NCP3065 is rated for commercial/industrial temperature ranges and the NCV3065 is automotive qualified. This evaluation board user’s manual describes a DC−DC converter circuits that can easily be configured to drive LEDs at several different output currents and can be configured for either AC or DC input. The NCP3065/NCV3065 can be configured in a several driver topologies to a drive string of LEDs: be it traditional low power LEDs or high brightness high power LEDs such as the Lumileds Luxeon K2 and Rebel series, the CREE XLAMP 4550 or XR series, the OSRAM OSTAR, TopLED and Golden Dragon. Configurations like this are found in 12 VDC track lighting applications, automotive applications, and low voltage AC landscaping applications as well as track lighting such as under-cabinet lights and desk lamps that might be powered from standard off-the-shelf 5 VDC and 12 VDC wall adapters. The  Semiconductor Components Industries, LLC, 2012 November, 2012 − Rev. 1 Evaluation Board Design Versions The evaluation boards are designed to display the full functionality and flexibility of NCP3065 as a driver to drive various LEDs at the low voltage AC and DC sources. The components are selected for the 15 W LED driver 1 Publication Order Number: EVBUM2155/D NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB solutions. Each application is described by the schematic and the bill of material and it has the option of LED dimming by using an external PWM signal. application. Based on this circuit, there are many possible configurations with different input voltages and output power levels that could be derived by making some minor components changes. Table 1 shows these different circuit Table 1. COMPONENTS CHANGES FOR DIFFERENT CONFIGURATIONS LED Driver VIN ILED VF L COUT R8 Application (V) (mA) (V) (mH) (mF) (W) 12 VDC 1 W LED 10 − 14 350 3.6 47 150 100 0 12k 3k3 12 VDC 3 W LED 10 − 14 700 or 350 3.6 or 7.2 47 150 100 0 16k 12k 12 VDC 5 W LED 10 − 14 700 or 1,000 7.2 or 3.6 47 150 100 0 12k 12k 24 VDC 5 W LED 21 − 27 350 14 68 220 100 0 160k 39k 24 VDC 10 W LED 21 − 27 700 14 68 220 100 0 150k 100k 12 VAC 1 W LED 14 − 20 350 3.6 47 220 100 0 7k5 7k5 12 VAC 3 W LED 14 − 20 700 or 350 3.6 or 7.2 47 220 100 0 22k 22k 12 VAC 5 W LED 14 − 20 700 or 1,000 7.2 or 3.6 47 220 100 0 36k 100k/16k 12 VAC 5 W 14 − 20 350 14 47 220 100 0 NU NU 12 VAC 15 W 21 − 27 1,000 14 47 100 82k BUCK COMPONENT SELECTION Inductor ripple current specification to allow higher peak to peak values. This is achieved by configuring the NCP3065 in a continuous conduction buck configuration with low peak to peak ripple thus eliminating the need for an output filter capacitor. The important design parameter is to keep the peak current below the maximum current rating of the LED. Using 15% peak-to-peak ripple results in a good compromise between achieving max average output current without exceeding the maximum limit. This saves space and reduces part count for applications that require a compact footprint. For the common LED currents such as the 350 mA, 700 mA, 1,000 mA we setup inductor ripple current to the 52.5 mA, 105 mA, 150 mA. With respect these requirements we are able to select inductor value (Equation 1). When selecting an inductor there is a trade off between inductor size and peak current. In normal applications the ripple current can range from 15% to 100%. The trade off being that with small ripple current the inductance value increases. The advantage is that you can maximize the current out of the switching regulator. With Output Capacitor Operation A traditional buck topology includes an inductor followed by an output capacitor which filters the ripple. The capacitor is placed in parallel with the LED or array of LEDs to lower LED ripple current. With this approach the output inductance can be reduced which makes the inductance smaller and less expensive. Alternatively, the circuit could be run at lower frequency with the same inductor value which improves the efficiency and expands the output voltage range. Equation 2 is used to calculate the capacitor size based on the amount of LED ripple. L+ V IN * V OUT DI MAX T ON (eq. 1) Output Capacitor No Output Capacitor Operation When you choose output capacitor we have to think about its value, ESR and ripple current. A constant current buck regulator such as the NCP3065 focuses on the control of the current through the load, not the voltage across it. The switching frequency of the NCP3065 is in the range of 100 kHz − 300 kHz which is much higher than the human eye can detect. This allows us to relax the C OUT + http://onsemi.com 2 V IN * (1 * D) * D DI + DV * 8 * f 8 * L * f 2 * DV OUT (eq. 2) NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Current Feedback Loop the NCP3065 with dimming you can see in Figures 17 and 18 and dimming linearity in the Figure 19. As you can see in these figures there aren’t any delays in the rise or fall edges, which give us the required dimming linearity. To drive LEDs in a constant current mode, the feedback for the regulator is taken by sensing the voltage drop across the sensing resistor R12, see Figures 3 or 9. The RC circuit (R10 & C5) between the sense resistor and the feedback pin improves converter transient response. The low feedback reference voltage of 235 mV allows the use of low power and lower cost sense resistor. Equation 3 calculates the sense resistor value. I OUT + LED Current (mA) V REF R sense + 0.235 V R sense [A ] NCP3065 +VIN (eq. 3) 350 680 1/4W 700 330 1/4W 1000 220 1/4W Comp GND IPK 0R10 VCC C2 GND COMP J5 R11 ON/OFF 1k2 Q2 BC817−LT1G R9 10k Vout NCP3065 + J3 Sensing Resistor Value (mW) NC R1 J2 R10 1k 0805 R12 Rsense 1% Figure 4. NCP3065 Dimming Solution A I = 350 mA 700 mA, 1000 mA NCP3065 Rsense J2 +VIN + NC R1 R9 0R10 10k VCC C2 J3 GND Figure 3. NCP3065 Current Feedback COMP J5 Dimming Possibility R11 Q2 BC817−LT1G ON/OFF 1k2 The emitted LED light is proportional to average output (LED) current. The NCP3065 is capable of analog and digital PWM dimming. For the dimming we have three possibilities how to create it. We basically use a PWM signal with variable duty cycle for the managing output current value. The COMP or IPK pin of the NCP3065 is used to provide dimming capability. In digital input mode the PWM input signal inhibits switching of the regulator and reducing the average current through the LEDs. In analog input mode a PWM input signal is RC filtered and the resulting voltage is summed with the feedback voltage thus reduces the average current through the LEDs Figure 6. The component value of the RC filter are dependent on the PWM frequency. Due to this, the frequency has to be higher. Figure 19 illustrates the linearity of the digital dimming function with a 200 Hz digital PWM. The dimming frequency range for digital input mode is basically from 200 Hz to 1 kHz. For frequencies below 200 Hz the human eye will see the flicker. The low dimming frequencies are EMI convenient and an impact to it is small. The Figure 4 shows us an example of solution A, which uses the COMP pin to perform the dimming function and Figure 5 show us an example of solution B. The behavior of IPK R10 1k 0805 R12 Rsense 1% Figure 5. NCP3065 Dimming Solution B NCP3065 R1 J2 +VIN 0R10 + IPK VCC C2 J3 NC GND COMP J5 R11 ON/OFF R19 1k C9 R10 1k 0805 J5 LED R12 Rsense 1% Figure 6. NCP3065 Dimming Solution C http://onsemi.com 3 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB BOARD LAYOUT The layout of the evaluation board and schematic is shown below in Figure 7 and Figure7. Figure 7. Evaluation Board Layout Top (Not in Scale) Figure 8. Evaluation Board Silk Screen Top http://onsemi.com 4 5 http://onsemi.com R11 Figure 9. NCP3065 3A Buck Evaluation Board Schematic R11 ON/OFF 1k2 0805 J6 ON/OFF 1k2 0805 J6 +VAUX J4 GND J3 +VIN J2 0R04 R1 R3 R4 R5 R6 R7 220 mF/50 V 0.1mF Q1 BC807−LT1G C2 + C4 + C7 C8 IPK NC SWC SWE 1k C5 6k8 R13 NU 1k 0805 100pF 1.8nF C3 10k 0805 CT R8 MMSD4148T1G D2 R10 R14 NU NCP3065 SOIC8 VCC TCAP COMP COMP GND VCC IPK NC U1 R15 R9 Q2 BC817−LT1G 1mF/50V 0.1mF 1206 12061206 1206 1206 1206 R2 6 1R0 1%R Q5 MMBT3904LT1G Q4 MTB30P06VT4G R16 0R15 1% 0.1mF 1206 C1 R12 0R15 1% D1 MBRS540LT3G DO5040H−223MLB L1 + GND J7 −LED J5 C6 220 mF/50 V +LED J1 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB 6 http://onsemi.com Figure 10. NCP3065 Buck Evaluation Board Schematic R11 R11 ON/OFF 1k2 J6 ON/OFF 1k2 J6 +VAUX J4 GND J3 +VIN J2 R3 R4 R5 R6 R7 220mF/50V 0.1mF Q1 IPK NC SWC SWE 1k C5 R13 NU 1k 0805 100pF 1.8nF C3 15k 10k CT R8 MMSD4148 D2 R10 R14 NU NCP3065 SOIC8 VCC TCAP COMP COMP GND VCC IPK NC U1 R9 Q2 BC817−LT1G C2 + C4 1206 12061206 1206 1206 1206 R2 BC807−LGT1G 0R10 R1 6x 1R0 $1%R R15 Q5 MMBT3904LT1G Q4 NTF2955T1G C1 R12 Rsense $1% MBRS140LT3G 0.1mF 1206 D1 L1 GND J7 −LED J5 +LED C6 NU + J1 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Table 2. BILL OF MATERIAL FOR THE NCP3065 3A BUCK EVALUATION BOARD* Designator Qty. Description Value Tolerance Footprint Manufacturer Manufacturer Part Number Substitution Allowed U1 1 DC-DC Controller NCP3065 − SOIC8 ON Semiconductor NCP3065DR2G No C1, C4 2 Ceramic Capacitor 100 nF 10% 1206 Kemet C1206F104K1RAC Yes C2, C6 2 Electrolytic Capacitor 220 mF/50 V 10% G, 1010.2 Panasonic EEEVFK1H221P Yes C3 1 Ceramic Capacitor 1.8 nF 10% 0805 AVX 08055F182K4Z2A Yes C5 1 Ceramic Capacitor 100 pF 5% 0805 AVX 08051A101JAT2A Yes D1 1 Schottky Rectifier 5 A, 40 V − SMC ON Semiconductor MBRS540LT3G No D2 1 Switching Diode MMSD4148 − SOD123 ON Semiconductor MMSD4148T1G No L1 1 Surface Mount Power Inductor 22 mH 20% − Coilcraft DO5040H−223MLB Yes Q4 1 Power MOSFET, P-channel MTB30P06V − D2PAK ON Semiconductor MTB30P06VT4G No Q5 1 General Purpose Transistor MMBT3904 − SOT23 ON Semiconductor MMBT3904LT1G No R1 1 Resistor 40 mW, 0.5 W 1% 2010 Vishay/Dale WSL−2010.04 1% EB E3 Yes R8 1 Resistor 12 kW 1% 0805 Phycomp 232273461202 Yes R9 1 Resistor 10 kW 1% 0805 Phycomp 232273461003 Yes R10, R15 2 Resistor 1 kW 1% 0805 Phycomp 232273461002 Yes R11 1 Resistor 1.2 kW 1% 0805 Phycomp 232273461202 Yes R12, R16 2 Resistor 150 mW 1% 2010 Vishay/Dale WSL−2010.15 1% EB E3 Yes VIN, GND, ON/OFF, VAUX, LED+, LED− 7 Test Post − − − Vector Electronics K24C/M Yes Q1 1 Transistor PNP BC807 − SOT23 ON Semiconductor BC807−40LT1G Yes Q2 1 Transistor NPN BC817 − SOT23 ON Semiconductor BC817−40LT1G Yes Manufacturer Part Number Substitution Allowed *All devices are Pb-free. Table 3. BILL OF MATERIAL FOR THE NCP3065 BUCK EVALUATION BOARD* Designator Qty. Description Value U1 1 DC−DC Controller NCP3065 C2 1 Capacitor 220 uF/50 V C3 1 Ceramic Capacitor 1.8 nF C5 1 Ceramic Capacitor 100 pF C6 1 Electorlytic Capacitor D1 1 D2 1 L1 Tolerance Footprint Manufacturer − SOIC8 ON Semiconductor NCP3065DR2G No 20% G, 1010.2 Panasonic EEEVFK1H221P Yes 10% 0805 AVX 08055F182K4Z2A Yes 5% 0805 AVX 08051A101JAT2A Yes 100 mF, 50 V 20% F, 810.2 Panasonic EEEVFK1H101P Yes Schottky Rectifier 1 A, 40 V − SMB ON Semiconductor MBRS140LT3G No Switching Diode MMSD4148 − SOD123 ON Semiconductor MMSD4148T1G No 1 Surface Mount Power Inductor 47 mF 20% − Coilcraft DO3316P−473MLD Yes Q4 1 Power MOSFET, P-channel NTF2955 − SOT223 ON Semiconductor NTF2955T1G No Q5 1 General Purpose Transistor MMBT3904 − SOT23 ON Semiconductor MMBT3904LT1G No R1 1 Resistor 100 mW, 0.5 W 1% 2010 VISHAY DALE WSL−2010.1 1% EB E3 Yes R8 1 Resistor 12 kW 1% 0805 PHYCOMP 232273461202 Yes R9 1 Resistor 10 kW 1% 0805 PHYCOMP 232273461003 Yes R10, R15 2 Resistor 1 kW 1% 0805 PHYCOMP 232273461002 Yes R11 1 Resistor 1.2 kW 1% 0805 PHYCOMP 232273461202 Yes R12 1 Resistor 680 mW 1% 1206 PHYCOMP 235051916807 Yes *All devices are Pb-free. http://onsemi.com 7 CON3 J2 D3 D5 8 http://onsemi.com 1k2 0805 R3 SWC SWE C5 R2 1k 0805 100pF 1.8nF C2 10k 0805 CT R5 NCP3065 SOIC8 COMP VCC TCAP COMPGND IPK NC U1 Q1 BC817−LT1G R4 VCC MBRS2040LT3 MBRS2040LT3 D4 + 100nF C3 220mF/35V MBRS2040LT3 MBRS2040LT3 C4 D2 VCC 0.15R/0.5W R1 R6 0.68W 1206 J4 LED C1 1mF 1206 R7 0.68W 1206 R8 0.68W 1206 Jumper1 Jumper2 J3 MBRS2040LT3 D1 L1 OUTPUT J1 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Figure 11. Schematic NCP3065 as Switcher in the AC Input LED Driver Application NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Table 4. 12 VDC INPUT 1 W LED DRIVER WITHOUT OUTPUT CAPACITOR BILL OF MATERIALS Qty Reference Part Description Mfg P/N 2 C1, C4 100 nF, Ceramic Capacitor − 1 C2 220 mF/50 V, Electrolytic Capacitor EEEVFK1H221P 1 C3 1.8 nF, Ceramic Capacitor − 1 C5 100 pF, Ceramic Capacitor − 1 D1 1 A, 40 V Schottky Rectifier MBRS140LT3G 1 D2 Switching Diode MMSD4148T1G 1 L1 Surface Mount Power Inductor 1 Q4 1 Q5 1 R1 1 R8 1 2 1 1 1 U1 Mfg Package Mtg − 1206 SMD Panasonic G, 1010.2 SMD − 0805 SMD − 0805 SMD ON Semiconductor SMB SMD ON Semiconductor SOD123 SMD DO3340P−154MLD Coilcraft − SMD Power MOSFET, P-channel NTF2955T1G ON Semiconductor SOT223 SMD General Purpose Transistor MMBT3904LT1G ON Semiconductor SOT23 SMD 100 mW, 0.5 W − − 2010 SMD 3k3, Resistor − − 0805 SMD R9 10 kW, Resistor − − 0805 SMD R10, R15 1 kW, Resistor − − 0805 SMD R11 1.2 kW, Resistor − − 0805 SMD R12 680 mW, 1% − − 1206 SMD DC−DC Controller NCP3065 ON Semiconductor SOIC8 SMD Package Mtg Table 5. 12 VDC INPUT 1 W LED DRIVER WITH OUTPUT CAPACITOR BILL OF MATERIALS Qty Reference Part Description Mfg P/N 2 C1, C4 100 nF, Ceramic Capacitor − − 1206 SMD 1 C2 220 mF/50 V, Electrolytic Capacitor EEEVFK1H221P Panasonic G, 1010.2 SMD 1 C3 1.8 nF, Ceramic Capacitor − − 0805 SMD 1 C5 100 pF, Ceramic Capacitor − − 0805 SMD 1 C6 100 mF/50 V, Electrolytic Capacitor EEEVFK1H101P Panasonic F, 810.2 SMD 1 D1 1 A, 40 V Schottky Rectifier MBRS140LT3G ON Semiconductor SMB SMD 1 D2 Switching Diode MMSD4148T1G ON Semiconductor SOD123 SMD 1 L1 Surface Mount Power Inductor DO3316P−473MLD Coilcraft − SMD 1 Q4 Power MOSFET, P-channel NTF2955T1G ON Semiconductor SOT223 SMD 1 Q5 General Purpose Transistor MMBT3904LT1G ON Semiconductor SOT23 SMD 1 R1 100 mW, 0.5 W − − 2010 SMD 1 R8 12k, Resistor − − 0805 SMD 1 R9 10 kW, Resistor − − 0805 SMD 2 R10, R15 1 kW, Resistor − − 0805 SMD 1 R11 1.2 kW Resistor − − 0805 SMD 1 R12 680 mW, 1% − − 1206 SMD 1 U1 DC−DC Controller NCP3065 ON Semiconductor SOIC8 SMD Table 6. 12 VDC INPUT 1 W LED DRIVERS TEST RESULTS Test Result Efficiency With Output Cap Without Output Cap 74% 72% Line regulation 3% Output Current Ripple With Output Cap Without Output Cap < 50 mA < 100 mA http://onsemi.com 9 Mfg NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Table 7. 12 VDC INPUT 3 W LED DRIVER WITHOUT OUTPUT CAPACITOR BILL OF MATERIALS Qty Reference Part Description Mfg P/N 2 C1, C4 100 nF, Ceramic Capacitor − 1 C2 220 mF/50 V, Electrolytic Capacitor EEEVFK1H221P 1 C3 1.8 nF, Ceramic Capacitor − 1 C5 100 pF, Ceramic Capacitor − 1 D1 2 A, 40 V Schottky Rectifier MBRS240LT3G 1 D2 Switching Diode MMSD4148T1G 1 L1 Surface Mount Power Inductor 1 Q4 1 Q5 1 R1 1 R8 1 2 1 1 1 U1 Mfg Package Mtg − 1206 SMD Panasonic G, 1010.2 SMD − 0805 SMD − 0805 SMD ON Semiconductor SMB SMD ON Semiconductor SOD123 SMD DO3340P−154MLD Coilcraft − SMD Power MOSFET, P-channel NTF2955T1G ON Semiconductor SOT223 SMD General Purpose Transistor MMBT3904LT1G ON Semiconductor SOT23 SMD 100 mW, 0.5 W − − 2010 SMD 12k, Resistor − − 0805 SMD R9 10 kW, Resistor − − 0805 SMD R10, R15 1 kW, Resistor − − 0805 SMD R11 1.2 kW, Resistor − − 0805 SMD R12 330 mW, 1% − − 1206 SMD DC−DC Controller NCP3065 ON Semiconductor SOIC8 SMD Package Mtg Table 8. 12 VDC INPUT 3 W LED DRIVER WITH OUTPUT CAPACITOR BILL OF MATERIALS Qty Reference Part Description Mfg P/N 2 C1, C4 100 nF, Ceramic Capacitor − − 1206 SMD 1 C2 220 mF/50 V, Electrolytic Capacitor EEEVFK1H221P Panasonic G, 1010.2 SMD 1 C3 1.8 nF, Ceramic Capacitor, − − 0805 SMD 1 C5 100 pF, Ceramic Capacitor, − − 0805 SMD 1 C6 100 mF/50 V, Electrolytic Capacitor EEEVFK1H101P Panasonic F, 8x10.2 SMD 1 D1 2 A, 40 V Schottky Rectifier MBRS240LT3G ON Semiconductor SMB SMD 1 D2 Switching Diode MMSD4148T1G ON Semiconductor SOD123 SMD 1 L1 Surface Mount Power Inductor DO3316P−473MLD Coilcraft − SMD 1 Q4 Power MOSFET, P-channel NTF2955T1G ON Semiconductor SOT223 SMD 1 Q5 General Purpose Transistor MMBT3904LT1G ON Semiconductor SOT23 SMD 1 R1 100 mW, 0.5 W − − 2010 SMD 1 R8 16k, Resistor − − 0805 SMD 1 R9 10 kW, Resistor − − 0805 SMD 2 R10, R15 1 kW, Resistor − − 0805 SMD 1 R11 1.2 kW, Resistor − − 0805 SMD 1 R12 330 mW, 1% − − 1206 SMD 1 U1 DC−DC Controller NCP3065 ON Semiconductor SOIC8 SMD Table 9. 12 VDC INPUT 3 W LED DRIVERS TEST RESULTS Test Result Efficiency With Output Cap Without Output Cap 76% 76% Line regulation 5% Output Current Ripple With Output Cap Without Output Cap < 50 mA < 90 mA http://onsemi.com 10 Mfg NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Table 10. 12 VDC INPUT 5 W LED DRIVER WITHOUT OUTPUT CAPACITOR BILL OF MATERIALS Qty Reference Part Description Mfg P/N 2 C1, C4 100 nF, Ceramic Capacitor − 1 C2 220 mF/50 V, Electrolytic Capacitor EEEVFK1H221P 1 C3 1.8 nF, Ceramic Capacitor − 1 C5 100 pF, Ceramic Capacitor − 1 D1 2 A, 40 V Schottky Rectifier MBRS240LT3G 1 D2 Switching Diode MMSD4148T1G 1 L1 Surface Mount Power Inductor 1 Q4 1 Q5 1 R1 1 R8 1 2 1 1 1 U1 Mfg Package Mtg − 1206 SMD Panasonic G, 1010.2 SMD − 0805 SMD − 0805 SMD ON Semiconductor SMB SMD ON Semiconductor SOD123 SMD DO3340P−154MLD Coilcraft − SMD Power MOSFET, P-channel NTF2955T1G ON Semiconductor SOT223 SMD General Purpose Transistor MMBT3904LT1G ON Semiconductor SOT23 SMD 100 mW, 0.5 W − − 2010 SMD 12k, Resistor − − 0805 SMD R9 10 kW, Resistor − − 0805 SMD R10, R15 1 kW, Resistor − − 0805 SMD R11 1.2 kW, Resistor − − 0805 SMD R12 220 mW, 1% − − 1206 SMD DC−DC Controller NCP3065 ON Semiconductor SOIC8 SMD Package Mtg Table 11. 12 VDC INPUT 5 W LED DRIVER WITH OUTPUT CAPACITOR BILL OF MATERIALS Qty Reference Part Description Mfg P/N 2 C1, C4 100 nF, Ceramic Capacitor − − 1206 SMD 1 C2 220 mF/50 V, Electrolytic Capacitor EEEVFK1H221P Panasonic G, 1010.2 SMD 1 C3 1.8n F, Ceramic Capacitor, − − 0805 SMD 1 C5 100 pF, Ceramic Capacitor, − − 0805 SMD 1 C6 100 mF/50 V, Electrolytic Capacitor EEEVFK1H101P Panasonic F, 810.2 SMD 1 D1 2 A, 40 V Schottky Rectifier MBRS240LT3G ON Semiconductor SMB SMD 1 D2 Switching Diode MMSD4148T1G ON Semiconductor SOD123 SMD 1 L1 Surface Mount Power Inductor DO3316P−473MLD Coilcraft − SMD 1 Q4 Power MOSFET, P Channel NTF2955T1G ON Semiconductor SOT223 SMD 1 Q5 General Purpose Transistor MMBT3904LT1G ON Semiconductor SOT23 SMD 1 R1 100 mW, 0.5 W − − 2010 SMD 1 R8 15k, resistor − − 0805 SMD 1 R9 10 kW, resistor − − 0805 SMD 2 R10, R15 1 kW, resistor − − 0805 SMD 1 R11 1.2 kW, resistor − − 0805 SMD 1 R12 220 mW, 1% − − 1206 SMD 1 U1 DC−DC controller NCP3065 ON Semiconductor SOIC8 SMD Table 12. 12 VDC INPUT 5 W LED DRIVERS TEST RESULTS Test Result Efficiency 75% Line regulation 4% Output Current Ripple With Output Cap Without Output Cap < 50 mA < 110 mA http://onsemi.com 11 Mfg 400 800 390 780 380 760 370 740 360 720 IOUT (mA) IOUT (mA) NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB 350 340 700 680 330 660 320 640 310 620 300 600 9 10 11 12 13 14 15 14 15 16 17 VIN (V) Figure 12. Current Regulation, 12 VDC Input 1 W LED Driver 20 21 95 1100 90 EFFICIENCY (%) 1050 IOUT (mA) 19 Figure 13. Current Regulation, 12 VAC Input 3 W LED Driver 1150 1000 950 85 80 75 900 850 10 18 VIN (V) 11 12 VIN (V) 13 14 70 14 Figure 14. Current Regulation, 12 VDC Input 5 W LED Driver 15 16 17 VIN (V) 18 19 Figure 15. 12 VAC Input 5 W LED Driver Efficiency http://onsemi.com 12 20 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Figure 16. 12 VDC, IOUT = 350 mA Input Inductor Ripple Without Output Capacitor, C1 Inductor Input, C4 Inductor Current Table 13. BUCK EFFICIENCY RESULTS FOR DIFFERENT RIPPLE WITH NO OUTPUT CAPACITOR Efficiency 1 LED, Vf = 3.6 V 2 LEDs, Vf = 3.6 V 4 LED, Vf = 14.4 V IOUT = 350 mA > 74% > 83% − IOUT = 700 mA > 76% > 83% − IOUT = 1,000 mA > 75% − − IOUT = 350 mA > 70% > 80% > 87% IOUT = 700 mA > 72% > 82% − IOUT = 1,000 mA > 70% − − IOUT = 350 mA − − > 82% IOUT = 700 mA − − > 86% IOUT = 1,000 mA − − > 87% VIN = 12 VDC VIN = 12 VAC VIN = 24 VDC http://onsemi.com 13 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Figure 17. NCP3065 Behavior with Dimming, Frequency is 200 Hz, Duty Cycle 50% Figure 18. NCP3065 Dimming Behavior, Frequency 1 kHz, Duty Cycle 50% 800 24 VIN, VF 3.6 V 700 ILED (mA) 600 500 400 12 VIN, VF 3.6 V 300 200 24 VIN, VF 7.2 V 100 0 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) Figure 19. Output Current Dependency on the Dimming Duty Cycle Pulse Feedback Design circuit will reduce this overshoot. This will result in a stabilized switching frequency and reduce the overshoot and output ripple. The pulse feedback circuit is implemented by adding an external resistor R8 between the CT pin and inductor input as shown in the buck schematic Figure 9. The resistor value is dependent on the input/output conditions and switching frequency. The typical range is 3k to 200k. Table 1 contains a list of typical applications and the recommended value for the pulse feedback resistor. Using an adjustable resistor in place of R8 when evaluating an application will allow the designer to optimize the value and make a final selection. The NCP3065 is a burst-mode architecture product which is similar but not exactly the same as a hysteretic architecture. The output switching frequency is dependent on the input and output conditions. The NCP3065 oscillator generates a constant frequency that is set by an external capacitor. This output signal is then gated by the peak current comparator and the oscillator. When the output current is above the threshold voltage the switch turns off. When the output current is below the threshold voltage the switch is turned on and gated with the oscillator. A simplified schematic is shown in Figure 20. This may cause possible overshoots on the output. Using the pulse feedback http://onsemi.com 14 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Oscillator Output from Peak Current Comparator LED Vref + − VSENSE Figure 20. Burst-Mode Architecture Figures 21 and 22 show the effect of the pulse feedback resistor on the switching waveforms and load current ripple. This results in a fixed frequency switching with constant duty cycle, which is only dependent upon the input and output voltage ratio. When the ratio (VOUT/VIN) is near 1 (high duty cycle) over the entire input voltage range, the pulse feedback is not needed. Figure 21. Switching Waveform Without Pulse Figure 22. Switching Waveform With Pulse Feedback Feedback BOOST CONVERTER EVALUATION BOARD Boost Converter Topology The Boost converter schematic is illustrated in Figure 24. When the low side power switch is turned on, current drawn from the input begins to flow through the inductor and the current Iton rises up. When the low side switch is turned off, the current Itoff circulates through diode D1 to the output capacitor and load. At the same time the inductor voltage is added with the input power supply voltage and as long as this is higher than the output voltage, the current continues to flow through the diode. Provided that the current through the inductor is always positive, the converter is operating in continuous conduction mode (CCM). On the next switching cycle, the process is repeated. Figure 23. NCP3065 Boost Evaluation Board http://onsemi.com 15 16 http://onsemi.com Figure 24. NCP3065 Boost Evaluation Board Schematic R10 ON/OFF 1k2 J7 +VAUX J6 GND J4 +VIN J2 0R15 R1 Q1 NU R11 Q2 BC817−40LT1G 100 mH 330 mF/25 V R6 0.1mF R5 C5 R3 R4 C3 + R2 6x 1R0 $1% R7 SWC SWE 1k0 R8 NCP3065 VCC TCAP COMP GND IPK NC U1 L1 R9 Rsense MM3Z36VT1G D2 2.2nF C4 D1 MBRS140LT3G 0.1mF C2 C1 100mF/ 50V + −LED J5 GND J3 +VOUT J1 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB When the pin voltage is higher than 0.235 V the switch transistor is off. You could connect an external PWM signal to pin ON/OFF and a power source to pin +VAUX to realize the PWM dimming function. When the dimming signal exceeds the turn on threshold of the external PNP or NPN transistor, the comp pin will be pulled up. A TTL level input can also be used for dimming control. The range of the dimming frequency is from 100 Hz to 1 kHz, but it is recommended to use frequency around 200 Hz as this is safely above the frequency where the human eye can detect the pulsed behavior, in addition this value is convenient to minimize EMI. There are two options to determine the dimming polarity. The first one uses the NPN switching transistor and the second uses a PNP switching transistor. The switch on/off level is dependent upon the chosen dimming topology. The external voltage source (VAUX) should have a voltage ranging from +5 VDC to +VIN. Figure 19 illustrates average LEDs current dependency on the dimming input signal duty cycle. For cycle by cycle switch current limiting a second comparator is used which has a nominal 200 mV threshold. The value of resistor R1 determines the current limit value and is configured according to the following equation. When operating in CCM the output voltage is equal to V OUT + V IN @ 1 1*D (eq. 4) The duty cycle is defined as D+ t ON t ON ) t OFF + t ON T (eq. 5) The input ripple current is defined as DI + V IN D f*L (eq. 6) The load voltage must always be higher than the input voltage. This voltage is defined as V load + V sense ) n * V f (eq. 7) where Vf = LED forward voltage, Vsense is the converter reference voltage, and n = number of LED’s in cluster. Since the converter needs to regulate current independent of load voltage variation, a sense resistor is placed across the feedback voltage. This drop is calculated as V sense + I load ) n * R sense (eq. 8) The Vsense corresponds to the internal voltage reference or feedback comparator threshold. I pk(SW) + Simple Boost 350 mA LED Driver I OUT + R sense (eq. 10) The maximum output voltage is clamped with an external zener diode, D2 with a value of 36 V which protects the NCP3065 output from an open LED fault. The evaluation board has a few options to configure it to your needs. You can use one 150 mW (R1) or a combination of parallel resistors such as six 1 W resistors (R2 − R7) for current sense. To evaluate the functionality of the board, high power LEDs with a typical Vf = 3.42 V @ 350 mA were connected in several serial combinations (4, 6, 8 LED’s string) and 4 chip and 6 chip LEDs with Vf = 14 V respectively Vf = 20.8 V @ 700 mA. The NCP3065 boost converter is configured as a LED driver is shown in Figure 24. It is well suited to automotive or industrial applications where limited board space and a high voltage and high ambient temperature range might be found. The NCP3065 also incorporates safety features such as peak switch current and thermal shutdown protection. The schematic has an external high side current sense resistor that is used to detect if the peak current is exceeded. In the constant current configuration, protection is also required in the event of an open LED fault since current will continue to charge the output capacitor causing the output voltage to rise. An external zener diode is used to clamp the output voltage in this fault mode. Although the NCP3065 is designed to operate up to 40 V additional input transient protections might be required in certain automotive applications due to inductive load dump. The main operational frequency is determined by the external capacitor C4. The ton time is controlled by the internal feedback comparator, peak current comparator and main oscillator. The output current is configured by an internal feedback comparator with negative feedback input. The positive input is connected to an internal voltage reference of 0.235 V with 10% precision over temperature. The nominal LED current is setup by a feedback resistor. This current is defined as: 0.235 0.2 + 1.33 A 0.15 Number of LEDs String Forward Voltage at 255C Min Typ Max 4 11.16 13.68 15.96 6 16.74 20.52 23.94 8 22.32 27.36 31.92 The efficiency was calculated by measuring the input voltage and input current and LED current and LED voltage drop. The output current is dependent on the peak current, inductor value, input voltage and voltage drop value and of course on the switching frequency. I OUT + (D * D 2) * (eq. 9) There are two approaches to implement LED dimming. Both use the negative comparator input as a shutdown input. D+ http://onsemi.com 17 ǒ I pk(SW) D * Ǔ V IN * V SWCE 2*L*f V OUT ) V F * V IN V OUT ) V F * V SWCE [*] [A] (eq. 11) (eq. 12) NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Where: VOUT VIN VF VSWCE Ipk(SW) D L f the regulated current to drop, Region2 is where the current is flat and represents normal operation, Region 3 occurs when VIN is greater than VOUT and there is no longer constant current regulation. Region 3 and 1 are included here for illustrative purposes as this is not a normal mode of operation. Figure 11 illustrates the additional circuitry required to support 12 VAC input signal which includes the addition of a bridge rectifier and input filter capacitor. The rectified dc voltage is Output Voltage Input Voltage Schottky Diode Forward Voltage Switch Voltage Drop Peak Switch Current Duty Cycle Inductor Value Switching Frequency Line regulation curve in Figure 26 illustrates three distinct regions; in the first region, the peak current to the switch is exceeded tripping the overcurrent protection and causing V INDC + Ǹ2 * V AC [ 17 V DC 95 (eq. 13) 400 390 380 Boost 6LED 350 mA 370 85 ILOAD (mA) EFFICIENCY (%) 90 Boost 4LED 350 mA 80 Boost 6LED 350 mA Boost 4LED 350 mA 360 350 340 330 320 75 310 70 6 8 10 14 12 16 18 20 300 22 6 8 10 12 14 16 18 20 22 VIN (V) VIN (V) Figure 25. Boost Converter Efficiency for 4 or 6 LEDs and Output Current 350 mA Figure 26. Line Regulation for 4 or 6 LEDs and Output Current 350 mA Table 14. BILL OF MATERIAL FOR THE NCP3065 BOOST EVALUATION BOARD* Designator Qty. Description Value U1 1 DC-DC Controller NCP3065 C1 1 Electrolytic Capacitor 100 mF/50 V C2, C5 2 Ceramic Capacitor 100 nF C3 1 Electrolytic Capacitor C4 1 D1 1 D2 Tolerance Manufacturer Part Number Substitution Allowed Footprint Manufacturer − SOIC8 ON Semiconductor NCP3065DR2G No 20% F, 810.2 Panasonic EEEVFK1H101P Yes 10% 1206 Kemet C1206F104K1RAC Yes 220 mF/50 V 20% G, 1010.2 Panasonic EEEVFK1H221P Yes Ceramic Capacitor 2.2 nF 10% 0805 AVX 08055F222KAT2A Yes Schottky Rectifier 1 A, 40 V − SMB ON Semiconductor MBRS140LT3G No 1 Zener Diode 36 V − SOD123 ON Semiconductor MM3Z36VT1G No L1 1 Surface Mount Power Inductor 100 mH 20% − Coilcraft DO3340P−104MLD Yes Q2 1 General Purpose Transistor BC817 − SOT23 ON Semiconductor BC817−40LT1G No R1 1 Resistor 150 mW, 0.5 W 1% 2010 VISHAY DALE WSL−2010.15 1% EB E3 Yes R8 1 Resistor 1 kW 1% 0805 PHYCOMP 232273461002 Yes R9 1 Resistor 680 mW 1% 1206 PHYCOMP 235051916807 Yes R10 1 Resistor 1.2 kW 1% 0805 PHYCOMP 232273461202 Yes *All devices are Pb-free. http://onsemi.com 18 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB Conclusion configured for a variety of constant current buck and boost LED driver applications. In addition there is an EXCEL tool at the ON Semiconductor website for calculating inductor and other passive components if the design requirements differ from the specific application voltages and currents illustrated in these example. LEDs are replacing traditional incandescent and halogen lighting sources in architectural, industrial, residential and the transportation lighting. The key challenge in powering LED’s is providing a constant current source. The evaluation board for the NCP3065/NCV3065 can be easily TEST PROCEDURE FOR THE NCP3065 3A BUCK EVALUATION BOARD + − A REGULATED DC SUPPLY V ELECTRONIC LOAD V − A + Figure 27. Test Setup for the NCP3065 3A Buck Evaluation Board Required Equipment     Test Procedure 1. Connect the test setup as shown in Figure 27. 2. Apply VOUT = 3.6 V load. 3. Apply an input voltage, VCC = 12 V. 4. Check that IOUT is 3,000 mA. 5. Power down the VCC. 6. Power down the load. 7. End of test. DC Voltage Supply, Up to 35 V, 4 A Voltage Meter Current Meter Electronic Load TEST PROCEDURE FOR THE NCP3065 BUCK EVALUATION BOARD + REGULATED DC SUPPLY − A V ELECTRONIC LOAD V − A + Figure 28. Test Setup for the NCP3065 Buck Evaluation Board Required Equipment     Test Procedure 1. Connect the test setup as shown in Figure 28. 2. Apply VOUT = 3.6 V load. 3. Apply an input voltage, VCC = 12 V. 4. Check that IOUT is 350 mA. 5. Power down the VCC. 6. Power down the load. 7. End of test. DC Voltage Supply, Up to 35 V, 3 A Voltage Meter Current Meter Electronic Load http://onsemi.com 19 NCP30653ABCKGEVB, NCP3065SOBCKGEVB, NCP3065SOBSTGEVB TEST PROCEDURE FOR THE NCP3065 BOOST EVALUATION BOARD + A − REGULATED DC SUPPLY V ELECTRONIC LOAD V − A + Figure 29. Test Setup for the NCP3065 Boost Evaluation Board Required Equipment     Test Procedure 1. Connect the test setup as shown in Figure 29. 2. Apply VOUT = 20 V load. 3. Apply an input voltage, VCC = 12 V. 4. Check that IOUT is 350 mA. 5. Power down the VCC. 6. Power down the load. 7. End of test. DC Voltage Supply, Up to 35 V, 3 A Voltage Meter Current Meter Electronic Load LUXEON is a registered trademark of Philips Lumileds Lighting Company and Royal Philips Electronics of the Netherlands. OSTAR, TopLED, and Golden DRAGON LED are registered trademarks of OSRAM Opto Semiconductors, Inc. XLamp is a registered trademark of Cree, Inc ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. SCILLC reserves the right to make changes without further notice to any products herein. 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