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| NCL30100 Fixed Off Time Switched Mode LED Driver Controller The NCL30100 is a compact switching regulator controller intended for space constrained constant current high-brightness LED driver applications where efficiency and small size are important. The controller is based on a peak current, quasi fixed-off time control architecture optimized for continuous conduction mode step-down (buck) operation. This allows the output filter capacitor to be eliminated. In this configuration, a reverse buck topology is used to control a cost effective N-type MOSFET. Moreover, this controller employs negative current sensing thus minimizing power dissipation in the current sense resistor. The off time is user adjustable through the selection of a small external capacitor, thus allowing the design to be optimized for a given switching frequency range. The control loop is designed to operate up to 700 kHz allowing the designer the flexibility to use a very small inductor for space constrained applications. The device has been optimized to provide a flexible inductive step-down converter to drive one or more high power LED(s). The controller can also be used to implement non-isolated buck-boost driver topologies. Features http://onsemi.com MARKING DIAGRAM TSOP-6 (SOT23- SC59-6, -6) XXXAYWG G SN SUFFIX CASE 318G 1 XXX A Y W G = Specific Device Code =Assembly Location = Year = Work Week = Pb--Free Package 1 PIN CONNECTIONS TSOP-6 CS GND CT 1 2 3 (Top View) 6 5 4 Gate VCC IVC Quasi-Fixed OFF Time, Peak Current Control Method N-FET Based Controller Architecture Up to 700 kHz Switching Frequency Up to >95% Efficiency No Output Capacitor Needed VCC Operation from 6.35 - 18 V Adjustable Current Limit with Negative Sensing Inherent Open LED Protected Very Low Current Consumption at Startup Undervoltage Lockout Compact Thin TSOP- Pb-6 -Free Package - to + 125C Operating Temperature Range -40 This is a Pb-Free Device Low Voltage Halogen LED Replacement (MR-16) LED Track Lighting Landscape Lighting Solar LED Applications Transportation Lighting 12 V LED Bulb Replacement Outdoor Area Lighting LED Light Bars ORDERING INFORMATION Device NCL30100SNT1G Package TSOP--6 (Pb--Free) Shipping 3000 / Tape & Reel Typical Applications For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. Semiconductor Components Industries, LLC, 2010 June, 2010 - Rev. 0 - 1 Publication Order Number: NCL30100/D NCL30100 6.5 - 24 V + C1 R1 R2 LED1 D1 LEDX L1 LED2 R3 IC1 NCL30100 CS DRV GND VCC CT IVC -C2 C3 R4 D2 Q1 Figure 1. Typical Application Example of the LED Converter PIN FUNCTION DESCRIPTION Pin N 1 2 3 4 5 Pin Name CS GND CT IVC VCC Function Current sense input Ground Timing capacitor Input voltage compensation Input supply Pin Description A resistor divider consisting of R3 and R4 is used to set the peak current sensed through the MOSFET switch Power ground. Capacitor to establish the off time duration The current injected into the input varies the switch off time and IPK allowing for feedforward compensation. Supply input for the controller. The input is rated to 18 V but as illustrated Figure 1, a simple zener diode and resistor can allow the LED string to be powered from a higher voltage Output drive for an external power MOSFET 6 DRV Driver output http://onsemi.com 2 NCL30100 IVC Input Voltage Regulator VOffset VDD Iref OFF Time Comparator Reference Regulator Undervoltage Lockout VCC 6.35/5.85 V 0--3.9 V CT 50 mA CS 12.5--50 mA Set S Gate Driver SET CLR Q Q DRV R Reset GND Current Sense Comparator Figure 2. Simplified Circuit Architecture MAXIMUM RATINGS Rating Power Supply Voltage IVC Pins Voltage Range CS and CT Pin Voltage Range Thermal Resistance, Junction--to--Air Junction Temperature Storage Temperature Range ESD Voltage Protection, Human Body Model (HBM) ESD Voltage Protection, Machine Model (MM) Symbol VCC IVC Vin RJA TJ Tstg VESD--HBM VESD--MM Value 18 --0.3 to 18 --0.3 to 10 178 150 --60 to +150 2 200 Unit V V V C/W C C kV V Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. 1. This device(s) contains ESD protection and exceeds the following tests: Human Body Model 2000 V per JEDEC Standard JESD22--A114E Machine Model 200 V per JEDEC Standard JESD22--A115--A 2. This device meets latchup tests defined by JEDEC Standard JESD78. 3. Moisture Sensitivity Level (MSL) 1. http://onsemi.com 3 NCL30100 ELECTRICAL CHARACTERISTICS (VCC = 12 V, for typical values TJ = 25C, for min/max values TJ = --40C to +125C, unless otherwise noted) SUPPLY SECTION Parameter INPUT VOLTAGE COMPENSATION Offset Voltage CT Pin Voltage CT Pin Voltage IVC pin internal resistance (Note 4) CT PIN - OFF TIME CONTROL Source Current Source Current Source Current Maximum Voltage Capability (Note 4) Minimum CT Pin Voltage (Note 4) Pin to ground capacitance (Note 4) Propagation Delay (Note 4) CURRENT SENSE Minimum Source Current Minimum Source Current Maximum Source Current Maximum Source Current Comparator Threshold Voltage (Note 4) Propagation Delay GATE DRIVER Sink Resistance Source Resistance POWER SUPPLY Startup Threshold Minimum Operating Voltage Vcc Hysteresis (Note 4) Startup Current Consumption Steady State Current Consumption (Note 4) Steady State Current Consumption 4. Guaranteed by design VCC = 6 V CDRV = 0 nF, fSW = 100 kHz, IVC = open, VCC = 7 V CDRV = 1 nF, fSW = 100 kHz, IVC = open, VCC = 7 V VCC increasing VCC decreasing VCC(on) VCC(off) VCC(hyst) ICC1 ICC1 ICC2 0.5 -5.45 --6.35 5.85 0.5 22 300 1 1.15 6.65 --35 V V V mA mA mA Isink = 30 mA Isource = 30 mA ROL ROH 5 20 15 60 40 100 CS Falling Edge to Gate Output IVC = 180 mA, CT Pin Grounded, 0 TJ 85C IVC = 180 mA, CT Pin Grounded, --40 TJ 125C IVC = 0 mA, CT Pin Grounded, 0 TJ 85C IVC = 0 mA, CT Pin Grounded, --40 TJ 125C ICS(min) ICS(min) ICS(max) ICS(max) Vth CSdelay 11. 75 11.35 47.25 45.25 --12.5 12.5 50 50 38 215 13.25 13.25 52.75 52.75 -310 mA mA mA mA mV ns CT Reach VCT Threshold to Gate Output Pin Unloaded, Discharge Switch Turned on CT Pin Grounded, 0 TJ 85C CT Pin Grounded, --40 TJ 125C ICT ICT VCT(max) VCT(min) CCT CTdelay 47.25 45.25 ----50 50 4.3 -8 220 52.75 52.75 -20 --mA mA V mV pF ns IVC Current = 25 mA (Including V(offset)) IVC Current = 50 mA (Including V(offset)) V(offset) VCT--25m VCT--50mA RIVC 1.10 1.69 2.12 1.30 2.08 2.6 17 1.45 2.47 3.05 V V V k Conditions Symbol Min Typ Max Unit http://onsemi.com 4 NCL30100 6.260 6.255 VCC(on) (V) 6.250 6.245 6.240 6.235 30 28 26 24 ICC1 (mA) --40 --20 0 20 40 60 80 100 120 22 20 18 16 14 12 10 --40 --20 0 20 40 60 80 100 120 TEMPERATURE (C) TEMPERATURE (C) Figure 3. Vstartup Threshold vs. Junction Temperature 5.780 5.775 5.770 VCC(off) (V) 5.765 5.760 5.755 5.750 5.745 --40 --20 0 20 40 60 80 TEMPERATURE (C) 100 120 5.740 Figure 4. Startup Current Consumption vs. Junction Temperature 12.6 12.5 12.4 12.3 ICS(min) (mA) 12.2 12.1 12.0 11.9 11.8 11.7 11.6 --40 --20 0 20 40 60 80 TEMPERATURE (C) 100 120 Figure 5. Minimum Source Current vs. Junction Temperature 1.10 50.0 49.5 1.05 ICS(max) (mA) 49.0 48.5 48.0 47.5 0.90 --40 47.0 --40 ICC2 (mA) Figure 6. Minimum Operating Voltage Threshold vs. Junction temperature 1.00 0.95 --20 0 20 40 60 80 TEMPERATURE (C) 100 120 --20 0 20 40 60 80 TEMPERATURE (C) 100 120 Figure 7. Steady State Current Consumption vs. Junction Temperature Figure 8. Maximum Source Current vs. Junction Temperature http://onsemi.com 5 NCL30100 55 50 45 40 35 30 25 --40 V(offset) (V) Vth (mV) 1.350 1.345 1.340 1.335 1.330 1.325 1.320 --40 --20 0 20 40 60 80 100 120 --20 0 20 40 60 80 100 120 TEMPERATURE (C) TEMPERATURE (C) Figure 9. Comparator Threshold Voltage vs. Junction Temperature 85 75 65 RESISTANCE () 55 45 35 25 15 5 --40 --20 0 20 ROL ROH ICT (mA) 51.0 50.5 50.0 49.5 49.0 48.5 48.0 47.5 60 80 100 120 47.0 --40 Figure 10. Offset Voltage vs. Junction Temperature 40 --20 0 20 40 60 80 100 120 TEMPERATURE (C) TEMPERATURE (C) Figure 11. Drive Sink and Source Resistance vs. Junction Temperature Figure 12. CT Source Current vs. Junction Temperature 2.60 2.55 CURRENT (mA) 2.50 2.45 2.40 2.35 2.30 --40 --20 0 20 40 60 80 100 120 TEMPERATURE (C) 50 45 40 35 30 25 20 15 10 5 0 0 20 40 60 80 100 120 140 CURRENT (mA) 160 180 200 VCT--50mA (V) Figure 13. CT Pin Voltage vs. Input Voltage Compensation Current Figure 14. IVC on ICT Dependence http://onsemi.com 6 NCL30100 APPLICATION INFORMATION The NCL30100 implements a peak current mode control scheme with a quasi-fixed OFF time. An optional input feedforward voltage control is provided to enhance regulation response with widely varying input voltages. Only a few external components are necessary to implement the buck converter. The NCL30100 incorporates the following features: Very Low Startup Current: The patented internal supply block is specially designed to offer a very low current consumption during startup. Negative Current Sensing: By sensing the total current, this technique does not impact the MOSFET driving voltage (VGS) during switching. Furthermore, the programming resistor together with the pin capacitance forms a residual noise filter which blanks spurious spikes. This approach also supports a flexible resistor selection. Finally unlike a positive sensing approach, there is virtually no power dissipation in the current sense resistor thus improving efficiency. Controller architecture supports high brightness LED drive current requirements: Selection of the external n-channel MOSFET can be easily optimized based on operation voltage, drive current and size giving the designer flexibility to easily make design tradeoffs. Typical 5.5% Current Regulation: The ICS pin offers 5.5% from 0 to 85C (+5.5% -9.5% across -40C to 125C) accuracy of the current typically, so the LED peak current is precisely controlled No output capacitor is needed: By operating the controller in continuous conduction mode, it is possible to eliminate the bulky output filter capacitor. The following section describes in detail each of the control blocks Current Sensing Block the switch and the inductor. This approach offers several benefits over traditional positive current sensing. Maximum peak voltage across the current sense resistor is user controlled and can be optimized by changing the value of the shift resistor. The gate drive capability is improved because the current sense resistor is located out of the gate driver loop and does not deteriorate the switch on and also switch off gate drive amplitude. Natural leading edge blanking is filter switching noise at FET turn-in The CS pin is not exposed to negative voltage, which could induce a parasitic substrate current within the IC and distort the surrounding internal circuitry. The current sensing circuit is shown in Figure 15. IVC Input Voltage Regulator 12.5--50 mA CS To Latch Vshift Rshift RCS GND Iprimary VCS The NCL30100 utilizes a technique called negative current sensing which is used to set the peak current through Figure 15. Primary Current Sensing http://onsemi.com 7 NCL30100 Once the external MOSFET is switched on, the inductor current starts to flow through the sense resistor RCS. The current creates a voltage drop VCS on the resistor RCS, which is negative with respect to GND. Since the comparator connected to CS pin requires a positive voltage, a voltage Vshift is developed across the resistor Rshift by a current source which level-shifts the negative voltage VCS. The level-shift current is in the range from 12.5 to 50 mA depending on the optional input voltage compensation loop control block signal (see more details in the input voltage compensation section). The peak inductor current is equal to: I pk = I CS R shift - V th R CS (eq. 1) GND From Input Voltage Compensation Block VOffset VOffset to VDD CT To Latch's Set Input CT 50 mA To Latch's Output To achieve the best Ipk precision, higher values of ICS should be used. The Equation 1 shows the higher drop on RCS reduces the influence of the Vth tolerance. Vth is the comparator threshold which is nominally 38 mV. A typical CS pin voltage waveform for continuous condition mode is shown in Figure 16. V Figure 17. OFF Time Control Ishift = 50 mA During the switch-on time, the CT capacitor is kept discharged by an internal switch. As soon as the latch output changes to a low state, the Isource is enabled and the voltage across CT starts to ramp-up until its value reaches the threshold given by the Voffset. The current injected into IVC can change this threshold. The IVC operation will be discussed in the next section. V VDD IVC Goes Up IVC Goes Down Ishift = 12.5 mA 0 Switch Turn on t CT pin Voltage Voffset Figure 16. CS Pin Voltage 0 I1 toff--min I2 I3 Figure 16 also shows the effect of the inductor current based on the range of control possible via the IVC input. OFF Time Control t Figure 18. CT Pin Voltage The internal current source, together with an external capacitor, controls the switch-off time. In addition, the optional IVC control signal can modulate the off time based on input line voltage conditions. This block is illustrated in Figure 17. The voltage that can be observed on CT pin is shown in Figure 18. The bold line shows the minimum IVC current when the off time is at its minimum. The amount of current injected into the IVC input can increase the off time by changing the turn off comparator switching threshold. I1, I2, http://onsemi.com 8 NCL30100 and I3 represent different delays depending on the magnitude of IVC. Gate Driver VCC The Gate Driver consists of a CMOS buffer designed to directly drive a power MOSFET. It features unbalanced source and sink capabilities to optimize switch on and off performance without additional external components. The power MOSFET is switched off at high drain current, to minimize its switch off losses the sink capability of the gate driver is increased for a faster switch off. On the other hand, the source capability of the driver is reduced to slow-down the power MOSFET at switch on in order to reduce EMI generation. Whenever the IC supply voltage is lower than the under voltage threshold, the Gate Driver is low, pulling down the gate to ground thus eliminating the need for an external resistor. Input Voltage Compensation: Current Mirror 1:1 17 k IVC Current Mirror 1:1 45 k VOffset To OFF Time Comparator Figure 19. Input Voltage Compensation, OFF Time Control The Input Voltage Compensation block gives the user optional flexibility to sense the input voltage and modify the current sense threshold and off time. This function provides a feed forward mechanism that can be used when the input voltage of the controller is loosely regulated to improve output current regulation. If the input voltage is well regulated, the IVC input can also be used to adjust the offset of the off time comparator and the current sense control to achieve the best current regulation accuracy. An external resistor connected between IVC and the input supply results in a current being injected into this pin which has an internal 17 k resistor connected to a current mirror. This current information is used to modify Voffset and ICS. By changing Voffset the off time comparator threshold is modified and the off time is increased. A small capacitor should be connected between the IVC pin and ground to filter out noise generated during switching period. Figure 19 shows the simplified internal schematic: OFF Time Comparator Input Voltage V VDD Voffset 0 IVC Pin Sink Current mA Figure 20. IVC Loop Transfer Characteristic The transfer characteristic (output voltage to input current) of the input voltage compensation loop control block can be seen in Figure 20. VDD refers to the internal stabilized supply. If no IVC current is injected, the off time comparator is set to Voffset. The value of the current injected into IVC also change Ics. This is accomplished by changing the voltage drop on Rshift. The corresponding block diagram of the IVC pin can be seen in Figure 21. To Current Sense Comparator 17 k IVC Current Mirror 4:3 CS 37.5 mA 12.5 mA Figure 21. Input Voltage Compensation Loop - Current Sense Control http://onsemi.com 9 NCL30100 The current sense characteristic can be seen in Figure 22. As illustrated, by varied the IVC current between 0 - 50 mA, the sourcing current can range from 12.5 to 50 mA. V 50 mA CS Pin Source Current 12.5 mA 0 mA 50 mA 100 mA IVC Pin Sink Current 140 mA mA Figure 22. Current Sense Regulation Characteristic Biasing the controller I pk V in The NCL30010 Vcc input can range up to 18 V. For applications that have an input voltage that is greater than that level, an external resistor should be connected between Vin and the VCC supply capacitor. The value of the resistor can be calculated as follows: R2 = V in - V CC I CC2 (eq. 2) t on = L + CS delay (eq. 4) Where: VCC - Voltage at which IC operates (see spec.) ICC2 - Current at steady state operation Vin - Input voltage The ICC current is composed of two components: The quiescent current consumption (300 mA) and the switching current consumption. The driver consumption depends on the MOSFET selected and the switching frequency. Total current consumption can be calculated using following formula: I CC = 300 10 --6 + C MOSFET V CC f switching (eq. 3) Where: L - Inductor inductance Ipk - Peak current As seen from the above equation, the turn on time depends on the input voltage. In the case of a low voltage AC input where there is ripple due to the time varying input voltage and input rectifier, natural frequency dithering is produced to improve the EMI signature of the LED driver. The turn off time is determined by the charging of the external capacitor connected to the CT pin. The minimum toff value can be computed as: t off = C T V offset I CT + CT delay (eq. 5) In applications where the input voltage Vin is varying dramatically, a zener can be used to limit the voltage going into VCC, thus reducing the switching current contribution. Switching Frequency Where: Voffset - Offset voltage (see parametric table) ICT - CT pin source current (see parametric table) Finally, the switching frequency then can be evaluated by: F SW = 1 = LI t on + t off pk V 1 + C V (eq. 6) in offset + 435 10 --9 5010 --6 T The switching frequency varies with the output load and input voltage. The highest frequency appears at highest input voltage. Since the peak inductor current is fixed, the on-time portion of the switching period can be calculated: The sum of the nominal CSdelay and CTdelay is approximately 435 nsec. http://onsemi.com 10 NCL30100 Reverse Buck Operating Description Figure 23 illustrates a typical application schematic and Figure 24 displays simplified waveforms illustrate the converter in steady state operation for critical circuit nodes. Imag Vin ICS Rshift ICT VCS Vsense CT VCT VDRV IC1 NCL30100 DRV VCC IVC 6 5 4 D1 Idemag L1 Q1 LED 1 CS 2 GND 3 CT Rsense Figure 23. Simplified Application Schematic http://onsemi.com 11 NCL30100 Vcc VDRV 0 Ipk Imag 0 Idemag Imin 0 I LED 0 50 uA ICT 0 VCT 0 0 V Sense I CS 0 VCS 38 mV 0 Figure 24. Voltage and Current Nodes in the Application Circuit The current follows the red line in Figure 23 when Q1 is turned on. The converter operates in continuous conduction mode therefore the current through the inductor never goes to zero. When the switch is on, the current creates a negative voltage drop on the Rsense resistor. This negative voltage can not be measured directly by the IC so an Rshift resistor is connected to CS pin. Inside the IC there is a current source connected to this pin. This current source creates constant voltage drop on resistor Rsense which shifts the negative voltage drop presented on Rsense positive. The magnetizing current Imag increases linearly, the negative voltage on Rsense increased as well. Thus the voltage on CS pin approaching zero. On the CS pin there is a comparator with a reference level of 38 mV. Once the voltage on the CS pin reaches this reference level, the DRV output is turned off and current path Imag disappears. Energy stored in the inductor as a magnetic field keeps current flowing in the same direction. The current path is now closed via diode D1 (green line). Once the DRV is turned off, the internal current source starts to charge the CT capacitor and the voltage on this node increases. Once the CT capacitor voltage reaches the VCT level, Q1 is turned on and an internal switch discharges the CT capacitor to be ready for the next switching cycle. http://onsemi.com 12 NCL30100 Application Design Example: A typical step down application will be used to illustrate the basic design process based on nominal design parameters: Input voltage: Vin - 12 Vac (12 V dc after the bridge) - Nominal LED current: LEDripple: VLED: Freewheel diode Vf: 700 mA (rms) 120 mA (peak- -peak) -to3.2 V 0.5 V Target Switching Frequency: 450 kHz Dimming using PWM signal 1 kHz with duty cycle 0 - 99% Vac 12 V D4 D5 C1 D6 D7 R3 R5 R2 R1 D1 D3 L3 Q1 A NCL30100 IC1 CS DRV GND VCC CT IVC Vac K Q2 C2 C5 R4 C3 D2 DIMM 0/5 V R9 R8 Figure 25. Example Design Schematic Note this simplified step- -step design process neglects -byany parasitic contribution of the PCB. First, we need to determine the nominal tON/tOFF ratio: V LED + V f 3.2 + 0.5 3.7 t on = = = t off 12 - 3.2 8.8 V in - V LED (eq. 7) Now all the parameters are defined to calculate inductor value: V= di L dt L= V IN - V LED t ON I ripple (12 - 3.2) 658 10 --9 0.12 (eq. 11) Next the typical duty cycle (DC) will be calculated: DC = t ON t ON + t OFF = 3.7 = 0.296 3.7 + 8.8 (eq. 8) = 48.3 mH Target switching frequency is set at 450 kHz, now we need to determine the period: T= 1 f op = 1 450 10 3 = 2.222 ms (eq. 9) A standard value 47 mH is chosen. Next the CT capacitor can be calculated, but we need to first determine the IVC current which can be simply calculated. I IVC = V 12 = 7.91 mA 6 + 17 10 3 R + R IVC 1.5 10 (eq. 12) Combination the previous equation we can calculate the tON and tOFF durations: t ON = DC T = 0.296 2.222 10 --6 = 658 ns (eq. 10) t OFF = (1 - DC) T = (1 - 0.296) 2.222 10 --6 = 1.564 ms The IVC current controls the dependence of the peak current to the input voltage. If the input voltage is well regulated, the IVC pin should be grounded. The value for IVC resistor should be chosen based on graphs below. Note as well that the IVC can be used to implement analog dimming since increasing the current into IVC pin will decrease the Ipeak of the LED). http://onsemi.com 13 NCL30100 1000 900 800 700 ILED (mA) 600 500 400 300 200 100 7 8 Rivc = 300k Rivc = 510k Rivc = 1 Meg Rivc = 1.5 Meg Rivc = 2.2 Meg Rivc = 3.7 Meg Rivc = infinity 600 500 400 ILED (mA) 300 200 100 0 Rivc = 300k Rivc = 510k Rivc = 1 Meg Rivc = 1.5 Meg Rivc = 2.2 Meg Rivc = 3.7 Meg Rivc = infinity 9 10 11 12 13 14 15 INPUT VOLTAGE (V) 16 17 18 7 8 9 10 11 12 13 14 15 INPUT VOLTAGE (V) 16 17 18 Figure 26. Rivc Impact versus Vin for ILED = 700 mA Nominal Figure 27. Rivc Impact versus Vin for ILED = 350 mA Nominal A value 1.5 M was used since the input voltage has a sinusoidal component due to the low voltage AC input and desires to have a small bulk capacitance, thus compensating for part of this variation. The dependence of VCT on IVC current is described by the following equation: V CT = --0.26 IVC 2 + 45.5 IVC + 1625 [V] (eq. 13) 1250 Using the result from Equation 12 and put it to Equation 13 the VCT threshold will be calculated: V CT = --0.26 7.91 10 --6 + 45.5 7.91 10 --6 + 1625 1250 (eq. 14) 2 subtracted from the calculated value in Equation 15. The calculated value is not standard, so the nearest value 33 pF has been selected. Now we can calculate the IPK of LED. The average value is set to 700 mA and the target ripple is set at 120 mA, the IPK equals 760 mA. Rshift has been chosen to be as small a voltage drop as possible to minimize power dissipation so an Rshift of 100 m has been selected. Before calculation of Rshift we need to know the ICS current, which affects the offset on Rshift. The ICS value dependents on the IVC current and for IVC currents between 0 - 50 mA, it can be described by this formula: I CS = --0.75 IVC + 50 10 --6 [mA] (eq. 16) 1.3 V Therefore: I CS = --0.75 IVC + 50 10 --6 = --0.75 7.91 10 --6 + 50 10 --6 44.07 mA (eq. 17) The CT capacitance can be calculated using the equations above: I= dv C dt C CT = I CT t OFF - CT delay V CT 1.3 (eq. 15) = 50 10 --6 1.654 10 --6 - 220 10 --9 55.1 pF The intrinsic pin capacitance CT pin (~8 pF) in conjunction with the dimming transistor (~10 pF) in this schematic approximately 18 pF so this value must be To calculate Rshift it is necessary to know the Ipk current through the inductor. From the time that the current sense comparator detects that the peak current threshold has been crossed to the time that the external MOSFET switch is turned off there is a propagation delay. Depending on the value of the inductor selected (which is based on the target switching frequency), there is a current error between the intended peak current and the actual peak current, this is illustrated in Figure 28. http://onsemi.com 14 NCL30100 Ipeak Ics ILED td (Vin-VLED) L -VLED - Vdiode L iL ton toff Figure 28. A Current Error Between the Intended Peak Current and the Actual Peak Current V= di L dt I delay = Vt L = 8.8 215 10 --9 47 10 --6 (eq. 18) Using the PDIE, we can calculate junction temperature: Temp IC = T A + P DIE R JA = T A + 0.0399 178 = T A + 7.1 C (eq. 21) 0.0402 A V/L is simply the slew rate through the inductor and td is the internal propagation delay so the current overshoot from target is approximately 40 mA as calculated in Equation 18. All values necessary for Rshift calculation are known, the Rshift value is described by this formula: R shift = = R sense I pk - I delay + V th I CS 0.1 (0.76 - 0.0402) + 0.038 44.07 10 --6 (eq. 19) 2496 This value of resistance can be a parallel combination of 2.7 k and 30 k. To understand the operating junction temperature, we calculate the die power dissipation: P DIE = V CC 300 10 --6 + C MOSFET V CC f switching = 12 300 10 --6 + 560 10 --12 12 450 10 3 = 39.8 mW (eq. 20) A design spreadsheet to aid in calculating the external components necessary for a specific set of operating conditions is available for download at the ON Semiconductor website. For a low voltage AC input diode D3 is placed into the Vcc line. Since Capacitor C3 is charged from a sinusoidal voltage. If the input voltage approaches zero, the IC is still supplied from C3. Due to this diode, the IC keeps the LED driver operating even if the sinusoidal voltage is lower than VCC(min) until Vin is lower than VLED. The use of this diode make sense only if a single LED is used and the converter is supplied by sinusoidal voltage 12 Vac. For two LEDs in series their forward voltage is almost as high as VCC(min) of the IC. Parasitic capacitance and inductance are presented in real applications which will have an influence on the circuit operation. They are depending on the PCB design which is user dependent. The BOM, PCB and some plots are enclosed for better understanding of the system behavior. http://onsemi.com 15 NCL30100 Figure 29. PCB Design the Circuit Calculated Above. Only Single Layer PCB is Used for the Application. Figure 30. The Component Side (Several Transistor Packages are Possible to Use) BILL OF MATERIALS FOR THE NCL30100 Designator C1 C2 C3 C5 D1 Qty 1 1 1 1 1 Description Capacitor Capacitor Capacitor Capacitor Surface Mount Schottky Power Rectifier Zener Diode Schottky Diode Schottky Diode Value 2.2 mF / 25 V 33 pF 4.7 mF / 25 V 1 nF MBR130T3G Tol 10% 5% 10% 10% -Footprint 0805 0603 0805 0603 SOD--123 Manufacturer AVX Kemet AVX Kemet ON Semiconductor Manufacturer Part Number 08053C225KAT2A C0603C330J5GACTU 08053D475KAT2A C0603C104K5RACTU MBR130T3G Substitution Allowed Yes Yes Yes Yes No Pb-Free Yes Yes Yes Yes Yes Comments D2 D3 D4, D5, D6, D7 IC1 L3 Q1 Q2 Q2 Q2 Q2 Q3 1 1 4 16 V NSR0520V2T1G NSR0340HT1G 5% --- SOD--523 SOD--523 SOD--323 ON semiconductors ON semiconductors ON semiconductors MM5Z16VT1G NSR0520V2T1G NSR0340HT1G No No No Yes Yes Yes 1 1 1 1 1 1 1 1 LED Driver Inductors Power MOSFET Power MOSFET Power MOSFET Power MOSFET Power MOSFET General Purpose Transistor NPN NCL30100 47 mH NTGS4141NT1G NU NU NU NU BC817--16 -10% ------- TSOP--6 WE--PD2_M TSOP--6 SOT--223 DPAK SOT--363 SOT--23 SOT--23 ON semiconductors Wurth Electronik ON semiconductors ON semiconductors ON semiconductors ON semiconductors ON semiconductors ON semiconductors NCL30100SNT1G 744774147 NTGS4141NT1G NTF3055--100T1G NTD23N03RT4G NTJS4160NT1G NTR4170NT1G BC817--16LT1G No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Option Option Option Option http://onsemi.com 16 NCL30100 BILL OF MATERIALS FOR THE NCL30100 Designator Q3 R1 R2 R3 R4 R5 R8 R9 Qty 1 1 1 1 1 1 1 1 Description Power MOSFET Resistor Resistor Resistor Resistor Resistor Resistor Resistor Value NU 1.5 M 300 R 30 k 0.1 R 2.7 k 10 k 5.6 k Tol -1% 1% 1% 1% 1% 1% 1% Footprint SOT--23 0603 0603 0603 0805 0603 0603 0603 Manufacturer ON semiconductors Rohm Semiconductor Rohm Semiconductor Rohm Semiconductor Welwyn Rohm Semiconductor Rohm Semiconductor Rohm Semiconductor Manufacturer Part Number NTS4001NT1G MCR03EZPFX1504 MCR03EZPFX3000 MCR03EZPFX3002 LRCS0805--0R1FT5 MCR03EZPFX2701 MCR03EZPFX1002 MCR03EZPFX5601 Substitution Allowed No Yes Yes Yes Yes Yes Yes Yes Pb-Free Yes Yes Yes Yes Yes Yes Yes Yes Comments Option Figure 31. Completed PCB with Devices Figure 32. Snapshot of CT Pin Voltage, Driver and ILED Figure 33. Voltage Measured on RCS (R4) http://onsemi.com 17 NCL30100 Figure 34. Current Through LED if 50% Dimming at 1 kHz is Applied Figure 35. The Dimming Detail at 95%. No Overshoot in LED Current is Observed Figures 36 and 37 illustrate leading edge and trailing edge waveforms from a chopped AC source. For proper dimming control, the bulk capacitance must be reduced to a relatively small value to achieve best dimming range. Performance in real world application is dependent on the characteristics of the actual dimmer and the electronic transformer used to generated to chopped AC waveform Figure 36. Trailing Edge Dimming Figure 37. Leading Edge (Triac) Regulation. Small Overshoot is Seen on the Leading Edge, this is Based on the Abrupt Chopping of the Low Voltage AC Waveform http://onsemi.com 18 NCL30100 Figure 38. ILED and Vin Waveform if No Dimming is Used 84 83 EFFICIENCY (%) 82 81 80 79 78 77 7 8 9 10 11 12 13 INPUT VOLTAGE (V) 14 15 16 DC Voltage Efficiency (No Bridge Rectifier) CURRENT (mA) 690 680 670 660 650 640 630 620 7 8 9 LED Current Variation 10 11 12 13 INPUT VOLTAGE (V) 14 15 16 Figure 39. Efficiency Measurement for the Demoboard (Vf = 3.2 Nominal) Figure 40. ILED Current Dependence on Input DC Voltage (No Bridge Rectifier is Used) Figure 39 represents the efficiency of the converter driving a single LED at a nominal current of 690 mA. The addition of the AC bridge rectifier contributes addition losses into the circuit and it is recommended to us low forward voltage schottky rectifiers to minimize power dissipation in the AC rectification stage. A specific two sided demo board was designed to fit with the MR- form factor. The schematic is almost the same -16 for both, but the PWM dimming control circuitry has been removed. If the same components are used, the operation frequency will be slightly higher due to the lower pin capacitance because the dimming transistor contribution is removed. http://onsemi.com 19 NCL30100 X2 D3 D7 D4 C1 D5 R1 R2 R3 R5 D1 12 V A X3 D6 NCL30100 CS DRV GND VCC CT IVC L1 Q1 K C2 C4 R4 C3 D2 Figure 41. Schematic MR 16 Application Figure 42. PCB Top Side MR 16 Application Figure 43. PCB Top Side Devices Placement Figure 44. PCB Bottom Side MR 16 Application http://onsemi.com 20 NCL30100 Figure 45. PCB Bottom Side Devices Placement Figure 46. Top Side Photo Figure 47. Bottom Side Photo http://onsemi.com 21 NCL30100 BILL OF MATERIALS FOR THE NCL30100 MR 16 APPLICATION Designator C1 C2 C3 C4 D1 Qty 1 1 1 1 1 Description Capacitor Capacitor Capacitor Capacitor Surface Mount Schottky Power Rectifier Zener Diode Schottky Diode Value 2.2 mF / 25 V 33 pF 4.7 mF / 25 V 1 nF MBR130T3G Tol 10% 5% 10% 10% -Footprint 0805 0603 0805 0603 SOD--123 Manufacturer AVX Kemet AVX Kemet ON Semiconductor Manufacturer Part Number 08053C225KAT2A C0603C330J5GACTU 08053D475KAT2A C0603C104K5RACTU MBR130T3G Substitution Allowed Yes Yes Yes Yes No Pb-Free Yes Yes Yes Yes Yes Comments D2 D3, D4, D5, D6 D7 IC1 L1 Q1 Q1 Q1 Q1 R1 R2 R3 R4 R5 1 4 16 V NSR0340HT1G 5% -- SOD--523 SOD--323 ON Semiconductor ON Semiconductor MM5Z16VT1G NSR0340HT1G No No Yes Yes 1 1 1 1 1 1 1 1 1 1 1 1 Schottky Diode LED Driver Inductors Power MOSFET Power MOSFET Power MOSFET Power MOSFET Resistor Resistor Resistor Resistor Resistor NSR0520V2T1G NCL30100 47 mH NTGS4141NT1G NU NU NU 1.5 M 300 R 30 k 0.1 R 2.7 k --10% ----1% 1% 1% 1% 1% SOD--523 TSOP--6 WE--PD2_M TSOP--6 SOT--223 SOT--363 SOT--23 0603 0603 0603 0805 0603 ON Semiconductor ON Semiconductor Wurth Electronik ON Semiconductor ON Semiconductor ON Semiconductor ON Semiconductor Rohm Semiconductor Rohm Semiconductor Rohm Semiconductor Welwyn Rohm Semiconductor NSR0520V2T1G NCL30100SNT1G 744774147 NTGS4141NT1G NTF3055--100T1G NTJS4160NT1G NTR4170NT1G MCR03EZPFX1504 MCR03EZPFX3000 MCR03EZPFX3002 LRCS0805--0R1FT5 MCR03EZPFX2701 No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Option Option Option Application Design Example for an Offline (115 Vac) Buck Application: In addition to traditional DC-DC applications, the NCL30100 can also be used in offline applications, a schematic and PCB layout are provided to illustrate a typical circuit configuration. Input voltage: Vin - 115 Vac - Nominal LED current: LEDripple: VLED: Freewheel diode Vf: 700 mA (rms) 120 mA (peak- -peak) -to3.2 V 0.5 V Target Switching Frequency: 50 kHz Dimming using PWM signal 1 kHz with duty cycle 0 - 99% In this application example, there is schematic and PCB only. The design steps are the same as above mentioned. http://onsemi.com 22 NCL30100 Vac CX1 2.2n D4 MRA4003 D1 MRA4003 L1 100u C1 D3 MRA4003 C2 47n A R1 24k R2 24k D2 MURA130 2.2u Vac D6 MRA4003 R3 150k IC1 NCL30100 CS DRV GND VCC D5 1N4148 Q1 MTD6N20ET L2 1mH K R4 5.6k R5 R33 C3 10p C4 560p CT IVC C5 1u R6 5.6k D7 16V DIMM 0/5 V Q2 BC817--16L GND R7 10k Figure 48. Design Example Schematic of 115 Vac Converter The input voltage in range 85-140 Vac is rectified by bridge rectifier D1, D3, D4 and D6. To limit current peaks generated during on time period, capacitor C1 is used. CX1, C2 and L1 are an EMI filter to protect mains against current spikes mainly generated by D2 if Q1 is turned on. The NCL30100 is powered through resistors R1 and R2. The Vcc voltage is limited by D7. Maximum LED current is set by resistors R3, R4 and R5. In this case Rsense is 0.33 to reach higher accuracy. A small capacitor C3 is used to filter out spikes which are generated during the turn off of diode D2. It is recommended to use L2 with low series resistance since current is flowing through the inductor continuously and D2 should be selected for low forward voltage drop and fast reverse recovery time. Figure 49. Component Side Figure 50. Single Layer PCB Design for this Application http://onsemi.com 23 NCL30100 Figure 51. ILED and Vin Waveform Figure 52. ILED at the Peak of Sinusoidal Voltage http://onsemi.com 24 NCL30100 Figure 53. Input Voltage and Input Current BILL OF MATERIALS FOR THE NCL30100 115 Vac Designator C1 C2 C3 C4 C5 D1, D3, D4, D6 D2 Qty 1 1 1 1 1 4 Description Capacitor Capacitor Capacitor Capacitor Capacitor Standard Recovery Power Rectifier Ultrafast Power Rectifier Standard Diode Zener Diode LED Driver Inductors Inductors Power MOSFET General Purpose Transistor NPN Power MOSFET Resistor Resistor Value 2.2 mF / 200 V 47 nF 10 pF 560 pF 1 mF / 25 V MRA4003T3G Tol 10% 10% 5% 5% 10% -Footprint E3.5--8 1206 0603 0603 0805 SMA Manufacturer Koshin Yageo Kemet Kemet AVX ON Semiconductor Manufacturer Part Number KR1 2.2u 200V 8X11.5 CC1206KKX7RABB473 C0603C100J5GACTU C0603C561J5GACTU 08053D105KAT2A MRA4003T3G Substitution Allowed Yes Yes Yes Yes Yes No Pb-Free Yes Yes Yes Yes Yes Yes Comments 1 MURA130T3G -- SMA ON Semiconductor MURA130T3G No Yes D5 D7 IC1 L1 L2 Q1 Q2 1 1 1 1 1 1 1 MMSD4148 16 V NCL30100 100 mH 1 mH MTD6N20 BC817--16 -5% -10% 10% --- SOD--123 SOD--123 TSOP--6 WE--PD4_L WE--PD_XXL DPAK SOT--23 ON Semiconductor ON Semiconductor ON Semiconductor Wurth Electronik Wurth Electronik ON Semiconductor ON Semiconductor MMSD4148T1G MMSZ16VT1G NCL30100SNT1G 7445620 7447709102 MTD6N20ET4G BC817--16LT1G No No No No No No No Yes Yes Yes Yes Yes Yes Yes Q2 R1, R2 R3 1 2 1 NU 24 k 150 k -1% 1% SOT--23 0806 0603 ON Semiconductor Rohm Semiconductor Rohm Semiconductor NTS4001NT1G MCR06EZPFX2402 MCR03EZPFX1503 No Yes Yes Yes Yes Yes Option http://onsemi.com 25 NCL30100 BILL OF MATERIALS FOR THE NCL30100 115 Vac Designator R4, R6 R5 R7 CX1 Qty 2 1 1 1 Description Resistor Resistor Resistor EMI Suppression Capacitor Value 5.6 k 0.33 R 10 k 2.2 nF / 300 V Tol 1% 1% 1% 20% Footprint 0603 0805 0603 XC10B5 Manufacturer Rohm Semiconductor Welwyn Rohm Semiconductor Epcos Manufacturer Part Number MCR03EZPFX5601 LRCS0805--0R33FT5 MCR03EZPFX1002 B32021A3222M289 Substitution Allowed Yes Yes Yes Yes Pb-Free Yes Yes Yes Yes Comments http://onsemi.com 26 NCL30100 PACKAGE DIMENSIONS TSOP-6 CASE 318G--02 ISSUE U D H 6 5 4 NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. MAXIMUM LEAD THICKNESS INCLUDES LEAD FINISH. MINIMUM LEAD THICKNESS IS THE MINIMUM THICKNESS OF BASE MATERIAL. 4. DIMENSIONS D AND E1 DO NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURRS. MOLD FLASH, PROTRUSIONS, OR GATE BURRS SHALL NOT EXCEED 0.15 PER SIDE. DIMENSIONS D AND E1 ARE DETERMINED AT DATUM H. 5. PIN ONE INDICATOR MUST BE LOCATED IN THE INDICATED ZONE. DIM A A1 b c D E E1 e L L2 M MIN 0.90 0.01 0.25 0.10 2.90 2.50 1.30 0.85 0.20 0 MILLIMETERS NOM MAX 1.00 1.10 0.06 0.10 0.38 0.50 0.18 0.26 3.00 3.10 2.75 3.00 1.50 1.70 0.95 1.05 0.40 0.60 0.25 BSC 10 -- L2 E GAUGE PLANE E1 1 NOTE 5 2 3 L b M C e c DETAIL Z SEATING PLANE 0.05 A1 A DETAIL Z RECOMMENDED SOLDERING FOOTPRINT* 0.60 6X 3.20 0.95 6X 0.95 PITCH DIMENSIONS: MILLIMETERS *For additional information on our Pb--Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303--675--2175 or 800--344--3860 Toll Free USA/Canada Fax: 303--675--2176 or 800--344--3867 Toll Free USA/Canada Email: orderlit@onsemi.com N. American Technical Support: 800--282--9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81--3--5773--3850 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative http://onsemi.com 27 NCL30100/D |
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