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NCL30105DR2G

NCL30105DR2G

  • 厂商:

    ONSEMI(安森美)

  • 封装:

    SOIC8

  • 描述:

    LED DRIVER, 2-SEGMENT, PDSO8

  • 数据手册
  • 价格&库存
NCL30105DR2G 数据手册
NCL30105 Constant Off Time PWM Current-Mode Controller for LED Applications The NCL30105 is a peak current controlled fixed off time controller designed for LED driver applications in which the LEDs are operated in deep Continuous Conduction Mode (CCM) without requiring slope compensation. Featuring an adjustable off time generator, the controller can drive a MOSFET up to a 500 kHz switching frequency. A dedicated dimming pin enables the use of a pulse−width modulated logic signal to dim the LEDs directly. The soft−start pin creates a startup sequence that slowly ramps up the peak current and enables the adjustment of the peak current setpoint for analog dimming control. The device features robust protection features to detect switch overcurrent faults and to detect maximum on time events. http://onsemi.com 8 1 SOIC−8 D SUFFIX CASE 751 MARKING DIAGRAM 8 Features • • • • • • • • L0105 ALYW G Constant Off Time Current−Mode Control Operation Adjustable Off Time (0.5 ms to 10 ms) Internal Leading Edge Blanking Source 250 mA / Sink 500 mA Peak Drive Capability ±3.2% Current Sense Accuracy at 25°C Internal Startup Delay 3.3 V Logic Level Dimming Input This is a Pb−Free Device 1 L0105 A L Y W G Safety Features = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package PIN CONNECTIONS • Thermal Shutdown • Maximum On Time Protection • Overcurrent Protection DIM SSTART Typical Application VCC GND CS DRV • • • • toff LED Backlight Drivers for LCD Panels LED Light Bars LED Street Lighting LED Bulbs 1 NC (Top View) ORDERING INFORMATION Device NCL30105DR2G Package Shipping† SOIC−8 2500 / Tape & Reel (Pb−Free) †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, 2012 May, 2012 − Rev. 2 1 Publication Order Number: NCL30105/D NCL30105 Vin LED1 CLED LEDN D L NCL30105 toff DIM VCC Rtoff NC DIM SSTART VCC GND CS DRV Soft−Start / Ipeak Adjustment CSSTART M Rsense CVCC Figure 1. Typical Application Diagram http://onsemi.com 2 NCL30105 Vcc VCC UVLO Von = VCC(on) Voff = VCC(off) Vtoff(open) NC ok = 1, else 0 ref 1 = reset 1 = reset tstart(delay) VSSTART(open) set current high = rst toff SET start pulse Q R S Q Q R Q / Iratio OVRI + ton > ton(MAX) VILIM VILIM(fault) tLEB(fault) GND − + + OVRI − S Q RDIM DIM SSTART SET toff generator Q VDIM(open) ISSTART Vcc tLEB down Nfault up count to Nfault CS DRV Figure 2. Internal Circuit Architecture Table 1. PIN FUNCTION DESCRIPTION Pin Number Pin Name Function 1 toff Adjusts the Off Time Duration 2 DIM Dimming Input 3 VCC Supplies the Controller 4 CS Current Sense Input 5 DRV Driver Output 6 GND − 7 SSTART Soft−start / Peak Current Adjustment 8 NC Non−connected Pin Pin Description A resistor to ground sets the off time duration. This pin is used for PWM dimming or to enable/disable the controller. An external auxiliary voltage connected to this pin supplies the controller. This pin monitors the peak current. When the peak current reaches the internal threshold, the DRV is turned off. The output of the driver is connected to an external MOSFET gate. The controller ground. A capacitor connected to this pin sets the soft−start duration. The voltage of this pin adjusts the peak current set point for analog dimming. Non−connected pin http://onsemi.com 3 NCL30105 Table 2. MAXIMUM RATINGS TABLE (Notes 1 – 4) Symbol Value Unit toff Voltage Vtoff −0.3 to 5.5 V toff Current Itoff ±10 mA DIM Voltage VDIM −0.3 to 7 V Rating DIM Current IDIM ±10 mA SSTART Voltage VSSTART −0.3 to 5.5 V SSTART Current ISSTART ±10 mA CS Voltage VCS −0.3 to 7 V CS Current ICS ±10 mA VDRV −0.3 to VCC V DRV Voltage DRV Sink Current IDRV(sink) 500 mA IDRV(source) 250 mA Supply Voltage VCC −0.3 to 22 V Supply Current ICC ±20 mA Power Dissipation (SO−8) (TA = 70°C, 2.0 Oz Cu, 55 mm2 Printed Circuit Copper Clad) PD 450 mW DRV Source Current Thermal Resistance Junction−to−Ambient (SO−8) (2.0 Oz Cu, 55 mm2 Printed Circuit Copper Clad) Junction−to−Air, Low conductivity PCB (Note 3) Junction−to−Air, High conductivity PCB (Note 4) RqJA Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 s) 178 168 127 °C/W TJ −40 to 150 °C TSTG −60 to 150 °C TL 300 °C 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 series contains ESD protection and exceeds the following tests: Pins 1 − 8: Human Body Model 2000 V per JEDEC Standard JESD22−A114E. Pins 1 − 8: Machine Model Method 200 V per JEDEC Standard JESD22−A115−A. Pins 1 − 8: Charged Device Model 2000 V per JEDEC Standard JESD22−C101C. 2. This device contains Latch−Up protection and exceeds ± 100 mA per JEDEC Standard JESD78. 3. As mounted on a 40x40x1.5 mm FR4 substrate with a single layer of 80 mm2 of 2 oz copper traces and heat spreading area. As specified for a JEDEC 51 low conductivity test PCB. Test conditions were under natural convection or zero air flow. 4. As mounted on a 40x40x1.5 mm FR4 substrate with a single layer of 650 mm2 of 2 oz copper traces and heat spreading area. As specified for a JEDEC 51 high conductivity test PCB. Test conditions were under natural convection or zero air flow. http://onsemi.com 4 NCL30105 Table 3. ELECTRICAL CHARACTERISTICS (Rtoff = 40.2 kW, VDIM = 3 V, CSSTART = 100 nF, VCS = 0 V, CDRV = 1 nF, VCC = 12 V, unless otherwise specified (For typical values, TJ = 25°C. For min/max values, TJ = −40°C to 125°C, unless otherwise specified)) Test Conditions Symbol Min Typ Max Unit Startup Voltage Threshold VCC Increasing VCC(on) 9 10 11 V Minimum Operating Voltage VCC Decreasing VCC(off) 8 8.8 10 V Supply Voltage Hysteresis VCC(on) − VCC(off) VCC(HYS) 1 1.2 1.5 V ICC(latch) − 510 900 mA VCC < VCC(on) − 500 mV ICC1 − 250 390 mA Device Disabled Current Consumption VDIM = 0 V ICC2 − 0.71 1.7 mA Device Switching Current Consumption fSW = 60 kHz ICC3 − 1.84 2.49 mA Drive Sink Resistance ISNK = 25 mA RSNK − 6.0 13.2 W Drive Source Resistance ISRC = 25 mA RSRC − 24 44 W Rise Time VDRV = 10% to 90% tr − 80 140 ns Fall Time VDRV = 90% to 10% tf − 25 60 ns Current Sense Voltage Threshold TJ =−40°C to 125°C TJ =25°C VILIM 0.95 0.977 1.01 1.01 1.05 1.042 V Current Sense Propagation Delay VCS = 0 V to 1.2 V Step, dV/dt = 10 V/ms VCS = VILIM to VDRV = 10% tILIM − 60 150 ns tLEB 470 545 670 ns Characteristic STARTUP AND SUPPLY CIRCUITS Current Consumption in Latch Mode Startup Current Consumption GATE DRIVE CURRENT SENSE Leading Edge Blanking Duration CONSTANT OFF TIME GENERATOR (Note 5) Off Time (Note 6) Rtoff = 5 kW Recommended Off Time Resistor Range toff1 0.87 1.02 1.13 ms Rtoff(range) 2.5 − 60 kW Minimum Off Time Rtoff = 0 W toff(MIN) 0.3 0.37 0.5 ms Maximum Off Time Rtoff = open toff(MAX) 10 11.77 14.5 ms Vtoff(REG) 0.95 1 1.05 V Rtoff = 0 W f(MAX) 500 − − kHz VSSTART = 3 V ISSTART 17 20 23 mA VSSTART = VILIM * Iratio Iratio 2.85 3 3.15 − VSSTART(open) 4.5 5 5.5 V ISSTART = 5 mA RDS(on)SSTART 200 350 500 W Dimming Enable Voltage Threshold VDIM Increasing VDIM(H) 1.8 2 2.2 V Dimming Disable Voltage Threshold VDIM Decreasing VDIM(L) 0.8 1 1.2 V VDIM(open) 4 4.5 5.5 V VDIM = 0 V RDIM 50 90 150 kW VDIM = 0 V to 3 V Step, dV/dt = 10 V/ms VDIM = VDIM(H) to VDRV = 90% twake − 0.28 1 ms toff Pin Regulated Voltage Maximum Switching Frequency (Note 7) SOFT−START Soft−Start Charge Current Soft−Start Voltage to Peak Current Set Point Ratio Soft−Start Pin Open Voltage Soft−Start Internal Discharge Switch Resistance DIMMING INPUT DIM Pin Open Voltage DIM Pin Internal Pull−Up Resistor Dimming Wake−Up Time 5. See Figure 17. 6. The tolerance of toff is guaranteed by design. 7. The thermal limitation of the device specified by the Maximum Ratings Table must not be exceeded. http://onsemi.com 5 NCL30105 Table 3. ELECTRICAL CHARACTERISTICS (Rtoff = 40.2 kW, VDIM = 3 V, CSSTART = 100 nF, VCS = 0 V, CDRV = 1 nF, VCC = 12 V, unless otherwise specified (For typical values, TJ = 25°C. For min/max values, TJ = −40°C to 125°C, unless otherwise specified)) Characteristic Test Conditions Symbol Min Typ Max Unit ton(MAX) 29.8 34 42.1 ms Nfault − 8 − − VILIM(fault) 1.5 1.6 1.7 V tILIM(fault) 10 70 150 ns tLEB(fault) 170 220 280 ns tLEB(fault)/tLEB tLEB(ratio) 0.3 0.4 0.8 − VCC = VCC(on) to VDRV = 90% tstart(delay) 100 130 172 ms Thermal Shutdown TJ = Increasing TSHDN 155 °C Thermal Shutdown Hysteresis TJ = Decreasing TSHDN(HYS) 40 °C TSHDN(delay) 75 ms PROTECTION Maximum On Time Number of Consecutive Maximum On Time Events or Overcurrent Events Overcurrent Current Sense Voltage Threshold Overcurrent Propagation Delay VCS = 0 V to 2 V Step, dV/dt = 10 V/ms VCS = VILIM(fault) to VDRV = 10% Overcurrent Leading Edge Blanking Duration Leading Edge Blanking Duration Ratio Startup Delay Thermal Shutdown Delay 5. See Figure 17. 6. The tolerance of toff is guaranteed by design. 7. The thermal limitation of the device specified by the Maximum Ratings Table must not be exceeded. http://onsemi.com 6 NCL30105 TYPICAL CHARACTERISTICS 9.8 VCC(off), MINIMUM OPERATING VOLTAGE (V) 10.0 VCC(on), STARTUP VOLTAGE THRESHOLD (V) 11.0 10.8 10.6 10.4 10.2 10.0 9.8 9.6 9.4 9.2 9.0 −50 −25 0 25 50 75 100 125 150 9.6 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 −50 −25 TJ, JUNCTION TEMPERATURE (°C) 310 1.3 ICC1, STARTUP CURRENT CONSUMPTION (mA) VCC(HYS), SUPPLY VOLTAGE HYSTERESIS (V) 330 1.4 1.2 75 100 125 150 1.1 1.0 0.9 0.8 0.7 290 270 250 230 210 190 170 0.6 −25 0 25 50 75 100 125 150 150 −50 −25 TJ, JUNCTION TEMPERATURE (°C) 0 25 50 75 100 125 150 TJ, JUNCTION TEMPERATURE (°C) Figure 5. Supply Voltage Hysteresis vs. Junction Temperature Figure 6. Startup Current Consumption vs. Junction Temperature 2.6 1.0 0.9 ICC3, DEVICE SWITCHING CURRENT CONSUMPTION (mA) ICC2, DEVICE DISABLED CURRENT CONSUMPTION (mA) 50 Figure 4. Minimum Operating Voltage vs. Junction Temperature 1.5 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 −50 25 TJ, JUNCTION TEMPERATURE (°C) Figure 3. Startup Voltage Threshold vs. Junction Temperature 0.5 −50 0 −25 0 25 50 75 100 125 150 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 −50 TJ, JUNCTION TEMPERATURE (°C) −25 0 25 50 75 100 125 TJ, JUNCTION TEMPERATURE (°C) Figure 7. Device Disabled Current Consumption vs. Junction Temperature Figure 8. Device Switching Current Consumption vs. Junction Temperature http://onsemi.com 7 150 NCL30105 1.10 600 1.08 590 tLEB, LEADING EDGE BLANKING DURATION (ns) VILIM, CURRENT SENSE VOLTAGE THRESHOLD (V) TYPICAL CHARACTERISTICS 1.06 1.04 1.02 1.00 0.98 0.96 0.94 0.92 0.90 −50 −25 0 25 50 75 100 125 580 570 560 550 540 530 520 510 500 −50 150 −25 TJ, JUNCTION TEMPERATURE (°C) 50 75 100 125 150 Figure 10. Leading Edge Blanking Duration vs. Junction Temperature 100 24 90 ISSTART, SOFT−START CHARGE CURRENT (mA) tILIM, CURRENT SENSE PROPAGATION DELAY (ns) 25 TJ, JUNCTION TEMPERATURE (°C) Figure 9. Current Sense Voltage Threshold vs. Junction Temperature 80 70 60 50 40 30 20 −50 −25 0 25 50 75 100 125 23 22 21 20 19 18 17 16 −50 150 −25 TJ, JUNCTION TEMPERATURE (°C) 0 25 50 75 100 125 150 TJ, JUNCTION TEMPERATURE (°C) Figure 11. Current Sense Propagation Delay vs. Junction Temperature Figure 12. Soft−Start Charge Current vs. Junction Temperature 3.15 1.15 Rtoff = 5 kW 3.10 1.10 toff, OFF TIME (ms) Iratio, SOFT−START VOLTAGE TO PEAK CURRENT SET POINT RATIO 0 3.05 3.00 2.95 2.90 1.05 1.00 0.95 0.90 2.85 −50 −25 0 25 50 75 100 125 150 0.85 −50 TJ, JUNCTION TEMPERATURE (°C) −25 0 25 50 75 100 125 150 TJ, JUNCTION TEMPERATURE (°C) Figure 13. Soft−Start Voltage to Peak Current Set Point Ratio vs. Junction Temperature Figure 14. Off Time vs. Junction Temperature http://onsemi.com 8 NCL30105 TYPICAL CHARACTERISTICS 14.0 toff(MAX), MAXIMUM OFF TIME (ms) 0.6 0.5 0.4 0.3 0.2 −25 0 25 50 75 100 13.0 12.5 12.0 11.5 11.0 10.5 10.0 9.0 −50 150 125 9.5 −25 0 25 50 75 100 125 TJ, JUNCTION TEMPERATURE (°C) TJ, JUNCTION TEMPERATURE (°C) Figure 15. Minimum Off Time vs. Junction Temperature Figure 16. Maximum Off Time vs. Junction Temperature 13 12 11 10 9 8 7 6 5 4 3 2 1 0 2.5 VILIM(fault), OVERCURRENT CURRENT SENSE VOLTAGE THRESHOLD (V) 150 50 ton(MAX), MAXIMUM ON TIME (ms) toff, OFF TIME (ms) 0.1 −50 13.5 12.5 22.5 32.5 42.5 52.5 45 40 35 30 25 20 −50 62.5 −25 0 25 75 100 125 TJ, JUNCTION TEMPERATURE (°C) Figure 17. Off Time vs. toff Pin Resistor Figure 18. Maximum On Time vs. Junction Temperature 1.80 150 2.5 1.75 1.70 1.65 1.60 1.55 1.50 1.45 1.40 −50 50 Rtoff, toff PIN RESISTOR (kW) VDIM, DIMMING VOLTAGE THRESHOLDS (V) toff(MIN), MINIMUM OFF TIME (ms) 0.7 −25 0 25 50 75 100 125 150 VDIM(H) 2.0 1.5 VDIM(L) 1.0 0.5 0.0 −50 TJ, JUNCTION TEMPERATURE (°C) −25 0 25 50 75 100 125 150 TJ, JUNCTION TEMPERATURE (°C) Figure 19. Overcurrent Current Sense Voltage Threshold vs. Junction Temperature Figure 20. Dimming Thresholds vs. Junction Temperature http://onsemi.com 9 NCL30105 TYPICAL CHARACTERISTICS 3.0 toff, OFF TIME (ms) 2.5 2.0 1.5 1.0 0.5 0.0 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 Rtoff, toff PIN RESISTOR (kW) Figure 21. Zoomed In Off Time vs. toff Pin Resistor http://onsemi.com 10 10.5 NCL30105 Application Information Introduction NCL30105 implements a current−mode architecture operated with a constant off time. The internal current set point and the external sense resistor determine the on time duration. The off time duration is adjusted with a resistor connected from the toff pin to ground. The constant off time operation enables deep continuous conduction mode operation without requiring slope compensation. The DIM pin enables the use of a PWM signal to modulate the switching pattern and adjust the average luminosity. The SSTART pin creates a soft−start that reduces the stress on the power components during startup and enables the use of an analog dimming signal to set the peak current by adjusting the SSTART pin voltage. • Constant Off Time Peak Current−Mode Operation: The constant off time technique enables the controller to operate a converter in deep continuous conduction mode without requiring slope compensation. The constant off time technique is inherently immune to sub−harmonic oscillations. • Off Time Adjustment: A pull−down resistor connected to the toff pin sets the off time duration. • Maximum On Time Protection: an internal circuit monitors the drive signal on time duration. If the drive on time duration reaches ton(MAX), the fault up/down counter is incremented by 1. If the drive on time duration reaches ton(MAX) during the next clock cycle, the counter is incremented again. If the drive on time duration does not reach ton(MAX) due to the current comparator being triggered during the next drive on time, the counter is decremented by 1. This sequence continues until the counter reaches 8. If the counter reaches 8, the NCL30105 is immediately latched off. When VCC is forced below VCC(off) and then above VCC(on), the latch is reset. • LED Short−Circuit Protection: If the CS pin voltage increases above VILIM(fault), the overcurrent comparator is triggered, which turns off the drive and increments the fault up/down counter by 1. If the overcurrent comparator is triggered again during the next drive on time, the counter is incremented again. If the overcurrent comparator is not triggered due to the current comparator being triggered during the next drive on time, the counter is decremented by 1. This sequence continues until the counter reaches 8. If the counter reaches 8, the part is immediately latched off. When VCC is forced below VCC(off) and then above VCC(on), the latch is reset. • Power On Delay: When VCC reaches VCC(on), the tstart(delay) timer begins counting, during which the drive is disabled. When tstart(delay) elapses, the SSTART • • • • • pin current source is enabled and the soft−start sequence begins. Soft−Start Operation: A capacitor connected to the SSTART pin is charged by an internal current source after the tstart(delay) timer period has elapsed. The soft−start period is completed when the SSTART pin voltage reaches VILIM*Iratio. The soft−start capacitor is discharged during the tstart(delay) to ensure the SSTART pin voltage begins charging from zero. Peak Adjustment: Analog dimming is achieved by forcing the SSTART pin below VILIM*Iratio, which lowers the peak current set point. Note: even if the SSTART pin is forced to 0 V, there is still a minimum on time every switching cycle. Under this condition, the minimum on time is the current sense leading edge blanking time plus the propagation delay to turn off the MOSFET and the off time is determined by the toff resistor value. Leading Edge Blanking: an internal circuit blinds the current sense comparator for a few hundred nanoseconds when the output drive goes high. The LEB ensures that controller remains insensitive to the turn−on voltage spikes observed on the CS pin due to the free−wheel diode recovery time. Dimming Input: a dedicated pin is provided to PWM modulate the LED current to reduce the LED luminosity. The circuit is driven on and off via a 3.3−V logic level signal. The DIM pin can also be used as an enable/disable pin, since the switching is disabled when there is a logic low signal applied to this pin. Thermal Shutdown: if the junction temperature of the controller exceeds an internal threshold, the drive is disabled. The drive remains disabled until the junction temperature decreases below the internal hysteresis threshold. The disabling of the drive protects the controller from destruction due to overheating. Startup Sequence When VCC reaches VCC(on), the NCL30105 maintains the drive low and the soft−start capacitor (CSSTART, connected to the SSTART pin) remains pulled to ground by the internal pull−down switch until the startup delay (tstart(delay)) elapses. Once the tstart(delay) period has elapsed, the drive is enabled and a soft−start sequence begins. The internal current source begins charging CSSTART and the voltage on the SSTART pin (VSSTART) begins increasing. The peak current set point is equal to VSSTART divided by Iratio. When VSSTART reaches the voltage that sets the maximum peak current (VSSTART = VILIM*Iratio), the soft−start sequence is complete and the peak current set point is equal to VSSTART divided by Iratio. Figure 22 describes a typical start−up sequence. http://onsemi.com 11 NCL30105 VCC VCC(on) VCC(off) Internal timer tstart(delay) reset reset VDRV VSSTART VSSTART(open) VSSTART = VILIM * Iratio User changes the setpoint VCS Soft−Start Sequence VILIM Constant Peak Soft−Start Sequence Variable Peak Figure 22. A Typical Startup Sequence Soft−Start Pin source, the current into the SSTART pin must be limited to ensure that the maximum current rating is not exceeded. It is recommended to set VSSTART by connecting a diode as shown in Figure 23. Using this configuration, the SSTART capacitor value to set a 15 ms soft−start duration (tSSTART) is calculated using Equation 1: The soft−start internal section is shown in Figure 23. The soft−start sequence is implemented using a current source that charges an external capacitor. The relationship between the capacitor voltage and the peak current voltage set point is Iratio. The maximum peak current set point is VSSTART/Iratio. For luminosity balancing purposes, it is possible to force the voltage on the SSTART pin from an external source. When forcing VSSTART with an external (eq. 1) I @t 20 m @ 15 m C SSTART + SSTART SSTART + + 0.1 mF 3 I ratio http://onsemi.com 12 NCL30105 latch reset VSSTART(open) Current comparator ISSTART − + SSTART / Iratio sensed current D2 1N4148 peak current setpoint control CSSTART VILIM tstart(delay) Timer reset UVLO reset Figure 23. The Soft−start Block Configuration to Set the Peak Current Setpoint Constant Off time Generator peak current threshold, the inductor value, and the input voltage. Unlike traditional peak current mode control, the fixed off time technique is not susceptible to sub−harmonic instability as shown in Figure 24: The controller operates with a constant off time technique. The off time technique is implemented by forcing a constant off time with the on time being set by the combination of the IL(t) constant DIL constant on off Figure 24. The Constant Off Time Technique is Immune to Sub−Harmonic Instabilities without Ramp Compensation The constant off time generator follows the principle sketched in Figure 25 where an internal timer is started at the end of each on time. Once the off time generator has elapsed, it begins the next DRV pulse. The off time is programmed by connecting a resistor from the toff pin to ground. The off time range is from 0.5 ms to 10 ms. In Figure 24, the perturbation is corrected in one switching cycle, despite a duty ratio greater than 50%. This benefit enables the designer to exclude slope compensation when operating the inductor in a deep continuous conduction mode. http://onsemi.com 13 NCL30105 on Drive off Internal timer adjustable constant Figure 25. A Timer is Started at the End of the On Time Duration Protection ton(MAX). The maximum on time limitation may occur if the input voltage is too low or if the CS pin is shorted to ground. After 8 consecutive maximum on times events, the controller is latched as shown in Figure 26. The NCL30105 includes several methods of protection. One of the protection features is the maximum on time limitation, which protects the system if the CS pin does not receive a signal. The on time is internally limited to Fault occurs here ton(MAX) Count 1 Controller is latched after the 8th event Smaller pulse: countdown 2 1 2 3 4 5 6 7 8 Figure 26. The Protection Feature Limits the Maximum On Time and Disables the Controller During a Fault in the circuit. The LEB circuit “blanks” the noise to ensure that the current and overcurrent comparators are not inadvertently triggered. If the LEB circuit is omitted, the noise causes the DRV to turn off before the required peak current is reached as shown in Figure 28. This causes the system to operate erratically. When the LEB circuit is included, the noise is “blanked” by blinding the current comparator for the LEB duration (tLEB) and the required peak current is reached as shown in Figure 29. The inclusion of the LEB circuits prevents the erratic operation of the system. Another protection feature is the overcurrent detection. The overcurrent detection activates when a short−circuit occurs in the inductor and LED string. To prevent false In latched mode, the controller consumes a low current and waits for a complete VCC cycle (VCC decreases to less than VCC(off) and then increased to greater than VCC(on)) to resume operation. The tracking of the fault events is implemented with an up/down counter. The counter is incremented by 1 when the ton(MAX) duration ends the driving pulse. The counter is decremented by 1 when a normal reset occurs via the current comparator. When the counter reaches 0, it stores this value and waits for an up pulse to change state. The NCL30105 includes Leading Edge Blanking (LEB) circuits to prevent inadvertent triggering of the current and overcurrent comparators. When the DRV pin goes high, noise is generated on the CS pin due to the parasitic elements http://onsemi.com 14 NCL30105 detection during surge tests, the controller uses the same counter as the maximum on time limitation. Due to the two different LEB circuits (tLEB and tLEB(fault)) configuration, if there is a severe overload, the overcurrent comparator is triggered first and the counter is incremented. If the overcurrent comparator is not triggered during the next clock cycle, the counter is decremented by the current comparator. Figure 27 depicts the logical arrangement inside the controller. In the presence of a fast rising signal, the overcurrent comparator is triggered first since tLEB(fault) VILIM < tLEB. When the overcurrent comparator output goes high, it resets the PWM latch and increments the counter. The counter can no longer increment or decrement until the next switching cycle. If during the time the overcurrent comparator output is high, tLEB elapses and causes the current comparator output to go high, the output of the current comparator is ignored due to the AND gate connection. Figure 30 illustrates the operation of the CS logic during an overcurrent fault. Only one up count or one down count is made per switching cycle. Current Comparator − latch off + CS tLEB tLEB(fault) Overcurrent Comparator + down Nfault up Count to Nfault − VILIM(fault) ton > ton(MAX) Q PWM reset Figure 27. CS Internal Logic VCS(t) VCS(t) Required peak current Noise “blanked” tILIM VILIM tILIM t VILIM Comparator Output DRV t down Inadvertant trigger tLEB VILIM VILIM Comparator Output t DRV DRV turned off before required peak current is reached down tLEB t t t Figure 29. Circuit with Leading Edge Blanking Figure 28. Circuit without Leading Edge Blanking http://onsemi.com 15 NCL30105 VCS(t) VILIM(fault) tILIM(fault) VILIM tILIM t VILIM(fault) Comparator up tLEB(fault) VILIM Comparator t Ignored down tLEB tLEB t DRV off t Figure 30. The Overcurrent Comparator Increments the Counter during a Fault Minimum Dimming Duty Cycle combination. The minimum dimming duty cycle is described in Figure 31 shown below. The first DRV pulse during the dimming duty cycle reaches the maximum on time, but the second DRV pulse does not and is turned off by the current comparator. If the dimming on time (duty cycle) is reduced, the second DRV pulse is turned off by the DIM pin voltage, the current comparator is not triggered, and the NCL30105 latches after 8 dimming cycles. During each DIM cycle if the max on time limit is reached a certain number of times, the current comparator must be triggered the same number of times to reset the fault counter. For each DIM cycle, if the maximum on time limit is reached a greater number of times than the number of times the current comparator is triggered, the fault counter is not reset and is incremented each DIM cycle until the fault count is reached (Nfault = 8). This results in a minimum dimming duty cycle for a particular LED string voltage and inductor Figure 31. Minimum Dimming Duty Cycle http://onsemi.com 16 NCL30105 Example Calculation R toff [kW] + The design begins with the system requirements. The following are the system requirements of an example system: Input Voltage (Vin) = 80 V Number of LEDs = 18 LED forward Voltage = 3.33 V LED string Voltage (VLED) = 60 V LED average current (ILED) = 350 mA Where toff is entered in ms and Rtoff is calculated in kW. R toff + 2.5 * 0.1214 + 12.76 kW 0.1864 Rtoff is selected as 12.7 kW. The inductor value is calculated using the off time: L+ LED ripple current (DILED) = 150 mA (±75 mA) Operating frequency = 100 kHz The switching period is calculated using the target operating frequency: T SW + 1 f SW L+ (eq. 1) Ǔ ǒ (eq. 3) 60 @ 2.5 m + 1 mH 150m I LED(peak) + I LED ) dILED 2 (eq. 4) I LED(peak) + 350m ) 150m + 425 mA 2 The off time (toff) is calculated using the LED string voltage, input voltage, and switching period: ǒ V LED @ t off dILED The LED peak current (ILED(peak)) is also the inductor peak current and is calculated using the average LED current and the LED ripple current: T SW + 1 + 10 ms 100k V t off + 1 * LED @ T SW V in t off [ms] * 0.1214 0.1864 It is critical that the inductor saturation current is greater than the peak current. Sufficient margin is generally set to 20%. For 20% margin, the inductor should be selected to have a saturation current greater than 510 mA. The sense resistor (Rsense) value is calculated using the peak current: (eq. 2) Ǔ t off + 1 * 60 @ 10 ms + 2.5 ms 80 R sense + To set toff, the following calculation is used based on the on the approximation of the linear region of the toff vs. Rtoff transfer function as shown in Figure 17: R sense + http://onsemi.com 17 V ILIM I LED(peak) 1 + 2.35 W 0.425 (eq. 5) NCL30105 Typical Application Schematic: Figure 32. Typical Application Schematic http://onsemi.com 18 NCL30105 Thermal Considerations: Layout Tips: The designer must ensure that the junction temperature of the NCL30105 remains less than the value of the maximum operating junction temperature in the Maximum Ratings Table for the worst−case operating conditions. The maximum junction temperature is calculated using the estimated current consumption. The estimated current consumption is calculated using the following assumptions: 1. The switching frequency is at the maximum of 500 kHz (fSW(MAX)). 2. The Vcc is at the maximum of 22 V (VCC(MAX)) 3. The gate of the MOSFET is modeled using a 1 nF capacitor (Cg) 4. The non−switching bias current is at the maximum of 1.56 mA (ICC2) Using these assumptions, the current consumption is calculated: Careful layout is critical for all switch−mode power supply design. Successful layout includes special consideration for noise sensitive pins of the controller IC. For the NCL30105 the following pins should be carefully routed: 1. Vcc: This pin requires a ceramic decoupling capacitor (typically 100 nF) and a electrolytic capacitor (typically 10 mF) to ensure that IC supply is constant and decoupled from high frequency noise generated by switching currents. 2. toff: This pin requires a resistor connected to ground to set the off time. It is not recommended to leave this pin open or shorted to ground to set the off time. The connection from the toff pin to the resistor and from the resistor to ground must be made as short as possible and connected directly to the NCL30105 GND pin. High noise nodes and traces must be routed as far away from this pin as possible. 3. SSTART: A capacitor is connected to this pin to set the Soft−Start time. The connection from the SSTART pin to the capacitor and from the capacitor to ground must be made as short as possible. 4. DIM: A decoupling capacitor may need to be connected to this pin if it coupled to high noise traces. The connection from the DIM pin to the capacitor and from the capacitor to ground must be made as short as possible. The addition of the capacitor may affect the response of time of the DIM signal to the DRV output. 5. CS: If LEB period is not long enough to ensure predictable operation, a small RC filter may need to be connected to this pin. The addition of the RC filter affects the current set point accuracy. 6. DRV: The trace that connects the DRV pin to the MOSFET must be made as short as possible to reduce the parasitic inductance of the trace. The DRV pin switches high currents and the parasitic inductance can cause higher than expected voltages to be applied to the gate of the MOSFET. A small resistor is recommended to be connected in series with the DRV pin to the gate. The resistor reduces the effect of the parasitic inductance. The addition of the resistor may affect the switching losses of the MOSFET. I CC(TJMAX) + ǒC g @ V CC @ f SW(MAX)Ǔ ) I CC2 I CC(TJMAX) + (1 n @ 22 @ 500 k) ) 1.56 m + 12.56 mA The power dissipation of the NCL30105 is calculated: P (TJMAX) + I CC(TJMAX) @ V CC(MAX) P (TJMAX) + 12.56 m @ 22 + 276 mW The junction temperature is calculated using the maximum thermal resistance (RqJA(MAX)) with the minimum PCB copper area from the maximum ratings table: T J(rise) + P (TJMAX) @ R qJA(MAX) T J(rise) + 0.276 @ 178 + 40 oC Assuming a maximum ambient temperature of 70°C (Tambient), the maximum junction temperature is calculated: T J(MAX) + T J(rise) ) T ambient T J(MAX) + 49 ) 70 + 119 oC Since this is less than the TSHDN parameter with sufficient margin, the design is acceptable. http://onsemi.com 19 NCL30105 Recommended Layout: Figure 33. Top Layout Figure 34. Bottom Layout http://onsemi.com 20 NCL30105 The critical components for layout are the following: 1. R2 (Rtoff): This resistor sets the off time. The placement of this resistor is such that the distance to the pin and IC ground is minimized. The footprints R1 and R3 are optional to increase the precision of the resistance value. 2. C5 (CVCC): This is the Vcc supply decoupling capacitor. The placement of this capacitor is such that the distance to the pin and IC ground is minimized. The recommended minimum value for this capacitor is 100 nF. 3. C8 (CSSTART): This capacitor sets the soft−start time. The placement of this capacitor is such that the distance to the pin and IC ground is minimized. The layout includes options to use a surface mount inductor (footprint L2) and MOSFET (footprint M2). http://onsemi.com 21 MECHANICAL CASE OUTLINE PACKAGE DIMENSIONS SOIC−8 NB CASE 751−07 ISSUE AK 8 1 SCALE 1:1 −X− DATE 16 FEB 2011 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. 6. 751−01 THRU 751−06 ARE OBSOLETE. NEW STANDARD IS 751−07. A 8 5 S B 0.25 (0.010) M Y M 1 4 −Y− K G C N X 45 _ SEATING PLANE −Z− 0.10 (0.004) H M D 0.25 (0.010) M Z Y S X J S 8 8 1 1 IC 4.0 0.155 XXXXX A L Y W G IC (Pb−Free) = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package XXXXXX AYWW 1 1 Discrete XXXXXX AYWW G Discrete (Pb−Free) XXXXXX = Specific Device Code A = Assembly Location Y = Year WW = Work Week G = Pb−Free Package *This information is generic. Please refer to device data sheet for actual part marking. Pb−Free indicator, “G” or microdot “G”, may or may not be present. Some products may not follow the Generic Marking. 1.270 0.050 SCALE 6:1 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0 _ 8 _ 0.010 0.020 0.228 0.244 8 8 XXXXX ALYWX G XXXXX ALYWX 1.52 0.060 0.6 0.024 MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0_ 8_ 0.25 0.50 5.80 6.20 GENERIC MARKING DIAGRAM* SOLDERING FOOTPRINT* 7.0 0.275 DIM A B C D G H J K M N S mm Ǔ ǒinches *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. STYLES ON PAGE 2 DOCUMENT NUMBER: DESCRIPTION: 98ASB42564B SOIC−8 NB Electronic versions are uncontrolled except when accessed directly from the Document Repository. Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red. PAGE 1 OF 2 onsemi and are trademarks of Semiconductor Components Industries, LLC dba onsemi or its subsidiaries in the United States and/or other countries. onsemi reserves the right to make changes without further notice to any products herein. onsemi makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does onsemi 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. onsemi does not convey any license under its patent rights nor the rights of others. © Semiconductor Components Industries, LLC, 2019 www.onsemi.com SOIC−8 NB CASE 751−07 ISSUE AK DATE 16 FEB 2011 STYLE 1: PIN 1. EMITTER 2. COLLECTOR 3. COLLECTOR 4. EMITTER 5. EMITTER 6. BASE 7. BASE 8. EMITTER STYLE 2: PIN 1. COLLECTOR, DIE, #1 2. COLLECTOR, #1 3. COLLECTOR, #2 4. COLLECTOR, #2 5. BASE, #2 6. EMITTER, #2 7. BASE, #1 8. EMITTER, #1 STYLE 3: PIN 1. DRAIN, DIE #1 2. DRAIN, #1 3. DRAIN, #2 4. DRAIN, #2 5. GATE, #2 6. SOURCE, #2 7. GATE, #1 8. SOURCE, #1 STYLE 4: PIN 1. ANODE 2. ANODE 3. ANODE 4. ANODE 5. ANODE 6. ANODE 7. ANODE 8. COMMON CATHODE STYLE 5: PIN 1. DRAIN 2. DRAIN 3. DRAIN 4. DRAIN 5. GATE 6. GATE 7. SOURCE 8. SOURCE STYLE 6: PIN 1. SOURCE 2. DRAIN 3. DRAIN 4. SOURCE 5. SOURCE 6. GATE 7. GATE 8. SOURCE STYLE 7: PIN 1. INPUT 2. EXTERNAL BYPASS 3. THIRD STAGE SOURCE 4. GROUND 5. DRAIN 6. GATE 3 7. SECOND STAGE Vd 8. FIRST STAGE Vd STYLE 8: PIN 1. COLLECTOR, DIE #1 2. BASE, #1 3. BASE, #2 4. COLLECTOR, #2 5. COLLECTOR, #2 6. EMITTER, #2 7. EMITTER, #1 8. COLLECTOR, #1 STYLE 9: PIN 1. EMITTER, COMMON 2. COLLECTOR, DIE #1 3. COLLECTOR, DIE #2 4. EMITTER, COMMON 5. EMITTER, COMMON 6. BASE, DIE #2 7. BASE, DIE #1 8. EMITTER, COMMON STYLE 10: PIN 1. GROUND 2. BIAS 1 3. OUTPUT 4. GROUND 5. GROUND 6. BIAS 2 7. INPUT 8. GROUND STYLE 11: PIN 1. SOURCE 1 2. GATE 1 3. SOURCE 2 4. GATE 2 5. DRAIN 2 6. DRAIN 2 7. DRAIN 1 8. DRAIN 1 STYLE 12: PIN 1. SOURCE 2. SOURCE 3. SOURCE 4. GATE 5. DRAIN 6. DRAIN 7. DRAIN 8. DRAIN STYLE 13: PIN 1. N.C. 2. SOURCE 3. SOURCE 4. GATE 5. DRAIN 6. DRAIN 7. DRAIN 8. DRAIN STYLE 14: PIN 1. N−SOURCE 2. N−GATE 3. P−SOURCE 4. P−GATE 5. P−DRAIN 6. P−DRAIN 7. N−DRAIN 8. N−DRAIN STYLE 15: PIN 1. ANODE 1 2. ANODE 1 3. ANODE 1 4. ANODE 1 5. CATHODE, COMMON 6. CATHODE, COMMON 7. CATHODE, COMMON 8. CATHODE, COMMON STYLE 16: PIN 1. EMITTER, DIE #1 2. BASE, DIE #1 3. EMITTER, DIE #2 4. BASE, DIE #2 5. COLLECTOR, DIE #2 6. COLLECTOR, DIE #2 7. COLLECTOR, DIE #1 8. COLLECTOR, DIE #1 STYLE 17: PIN 1. VCC 2. V2OUT 3. V1OUT 4. TXE 5. RXE 6. VEE 7. GND 8. ACC STYLE 18: PIN 1. ANODE 2. ANODE 3. SOURCE 4. GATE 5. DRAIN 6. DRAIN 7. CATHODE 8. CATHODE STYLE 19: PIN 1. SOURCE 1 2. GATE 1 3. SOURCE 2 4. GATE 2 5. DRAIN 2 6. MIRROR 2 7. DRAIN 1 8. MIRROR 1 STYLE 20: PIN 1. SOURCE (N) 2. GATE (N) 3. SOURCE (P) 4. GATE (P) 5. DRAIN 6. DRAIN 7. DRAIN 8. DRAIN STYLE 21: PIN 1. CATHODE 1 2. CATHODE 2 3. CATHODE 3 4. CATHODE 4 5. CATHODE 5 6. COMMON ANODE 7. COMMON ANODE 8. CATHODE 6 STYLE 22: PIN 1. I/O LINE 1 2. COMMON CATHODE/VCC 3. COMMON CATHODE/VCC 4. I/O LINE 3 5. COMMON ANODE/GND 6. I/O LINE 4 7. I/O LINE 5 8. COMMON ANODE/GND STYLE 23: PIN 1. LINE 1 IN 2. COMMON ANODE/GND 3. COMMON ANODE/GND 4. LINE 2 IN 5. LINE 2 OUT 6. COMMON ANODE/GND 7. COMMON ANODE/GND 8. LINE 1 OUT STYLE 24: PIN 1. BASE 2. EMITTER 3. COLLECTOR/ANODE 4. COLLECTOR/ANODE 5. CATHODE 6. CATHODE 7. COLLECTOR/ANODE 8. COLLECTOR/ANODE STYLE 25: PIN 1. VIN 2. N/C 3. REXT 4. GND 5. IOUT 6. IOUT 7. IOUT 8. IOUT STYLE 26: PIN 1. GND 2. dv/dt 3. ENABLE 4. ILIMIT 5. SOURCE 6. SOURCE 7. SOURCE 8. VCC STYLE 29: PIN 1. BASE, DIE #1 2. EMITTER, #1 3. BASE, #2 4. EMITTER, #2 5. COLLECTOR, #2 6. COLLECTOR, #2 7. COLLECTOR, #1 8. COLLECTOR, #1 STYLE 30: PIN 1. DRAIN 1 2. DRAIN 1 3. GATE 2 4. SOURCE 2 5. SOURCE 1/DRAIN 2 6. SOURCE 1/DRAIN 2 7. SOURCE 1/DRAIN 2 8. GATE 1 DOCUMENT NUMBER: DESCRIPTION: 98ASB42564B SOIC−8 NB STYLE 27: PIN 1. ILIMIT 2. OVLO 3. UVLO 4. INPUT+ 5. SOURCE 6. SOURCE 7. SOURCE 8. DRAIN STYLE 28: PIN 1. SW_TO_GND 2. DASIC_OFF 3. DASIC_SW_DET 4. GND 5. V_MON 6. VBULK 7. VBULK 8. VIN Electronic versions are uncontrolled except when accessed directly from the Document Repository. Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red. PAGE 2 OF 2 onsemi and are trademarks of Semiconductor Components Industries, LLC dba onsemi or its subsidiaries in the United States and/or other countries. onsemi reserves the right to make changes without further notice to any products herein. onsemi makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does onsemi 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. onsemi does not convey any license under its patent rights nor the rights of others. © Semiconductor Components Industries, LLC, 2019 www.onsemi.com onsemi, , and other names, marks, and brands are registered and/or common law trademarks of Semiconductor Components Industries, LLC dba “onsemi” or its affiliates and/or subsidiaries in the United States and/or other countries. onsemi owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. 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