NCP1246 ONSEMI [ON Semiconductor], NCP1246 Datasheet
NCP1246
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NCP1246 Summary of contents
Page 1
... Fixed Frequency Current Mode Controller for Flyback Converters The NCP1246 is a new fixedïfrequency currentïmode controller featuring the Dynamic SelfïSupply. This function greatly simplifies the design of the auxiliary supply and the V the internal startup current source to supply the controller during startï ...
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... Figure 1. Flyback Converter Application Using the NCP1246 PIN FUNCTION DESCRIPTION Pin No Pin Name Function 1 LATCH LatchïOff Input 2 FB Feedback + Shutdown pin 3 CS Current Sense 4 GND 5 DRV Drive output 6 VCC VCC input 8 HV Highïvoltage pin NCP1246 TYPICAL APPLICATION EXAMPLE Pull the pin up or down to latchïoff the controller. An internal current source allows the direct connection of an NTC for over temperature detection ...
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... NCP1246 SIMPLIFIED INTERNAL BLOCK SCHEMATIC Figure 2. Simplified Internal Block Schematic http://onsemi.com 3 ...
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... JEDEC 51-2 conductivity test PCB. Test conditions were under natural convection or zero air flow mounted 100 x 1.5 mm FR4 substrate with a single layer of 650 mm for a JEDEC 51-3 conductivity test PCB. Test conditions were under natural convection or zero air flow. NCP1246 Symbol pin, continuous voltage ...
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... J only Maximum on time 6. Internal supply current only, currents sourced via FB pin is not included (current is flowing in GND pin only). 7. Guaranteed by design pin source current is a sum of I and I bias NCP1246 = 25°C, for min/max values T J Test Condition Symbol V HV(min ...
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... FB 6. Internal supply current only, currents sourced via FB pin is not included (current is flowing in GND pin only). 7. Guaranteed by design pin source current is a sum of I and I bias NCP1246 = 25°C, for min/max values T J Test Condition Symbol kHz ...
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... TEMPERATURE SHUTDOWN Temperature shutdown Temperature shutdown hysteresis 6. Internal supply current only, currents sourced via FB pin is not included (current is flowing in GND pin only). 7. Guaranteed by design pin source current is a sum of I bias NCP1246 = 25°C, for min/max values T J Test Condition V going down FB ...
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... Figure 5. OffïMode HV Supply Current I 120 118 116 114 112 110 108 106 104 102 100 ï50 ï TEMPERATURE (°C) Figure 7. Brownïout Device Start Threshold V HV(start) NCP1246 TYPICAL CHARACTERISTIC 100 125 ï50 ï25 Figure 4. OffïState Leakage Current I 8.8 8.7 8.6 8.5 8.4 8.3 8 ...
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... TEMPERATURE (°C) Figure 13. Leading Edge Blanking Duaration t LEB NCP1246 TYPICAL CHARACTERISTIC 310 308 306 304 302 300 298 296 294 292 290 75 100 125 ï50 ï25 Figure 10. Frozen Current Setpoint V ...
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... TEMPERATURE (°C) Figure 17. Latch Pin High Threshold V 110 105 100 ï50 ï TEMPERATURE (°C) Figure 19. Current I Sourced from the NTC Latch Pin, Allowing Direct NTC Connection NCP1246 TYPICAL CHARACTERISTIC 5.20 5.15 5.10 5.05 5.00 4.95 4.90 4.85 4.80 4.75 4.70 75 100 125 ï50 ï25 Figure 16. FB Pin Open Voltage V 0.85 0.84 ...
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... TEMPERATURE (°C) Figure 23. Maximum ON Time t 65 kHz Version ï50 ï TEMPERATURE (°C) Figure 25. Maximum Duty Ratio D NCP1246 TYPICAL CHARACTERISTIC 100 100 125 ï50 ï25 Figure 22. Oscillator f 8.4 8.3 8.2 8.1 8.0 7.9 7.8 75 ...
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... TEMPERATURE (°C) Figure 29. FB Pin SkipïIn Level V 2.60 2.55 2.50 2.45 2.40 2.35 2.30 2.25 2.20 2.15 2.10 ï50 ï TEMPERATURE (°C) Figure 31. FB Pin Level V FB(OPCF) Which is the Overpower Compensation Applied NCP1246 TYPICAL CHARACTERISTIC 1.00 0.98 0.96 0.94 0.92 0.90 0.88 0.86 0.84 0.82 0.80 75 100 125 ï50 ï25 Figure 28. FB Pin Voltage Below Which Frequency Foldback Complete V FB(foldS) 0.88 0.86 0.84 0.82 ...
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... TEMPERATURE (°C) Figure 35. V Turnïoff Threshold (UVLO CC(off) 2.0 I CC1(100kHz) 1.9 1.9 I CC1(65kHz) 1.8 1.8 1.7 1.7 ï50 ï TEMPERATURE (°C) Figure 37. Internal Current Consumption when DRV Pin is Unloaded NCP1246 TYPICAL CHARACTERISTIC 11.5 11.3 11.1 10.9 10.7 10.5 10.3 10.1 9.9 9.7 9.5 75 100 125 ï50 ï25 Figure 34. HV Current Source Restart CC 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 75 ...
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... TEMPERATURE (°C) Figure 41. FB Pin Voltage Level Above Which is Entered On Mode V 150 145 140 135 130 125 120 ï50 ï TEMPERATURE (°C) Figure 43. Fault Timer Duration t NCP1246 TYPICAL CHARACTERISTIC 1.10 1.08 1.06 1.04 1.02 1.00 0.98 0.96 0.94 0.92 0.90 75 100 125 ï50 ï25 Figure 40. HV Signal Sampling Period T HV(hyst) ...
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... The NCP1246 is a multimode controller as illustrated in Figure 45. The mode of operation depends upon line and load condition. Under all modes of operation, the NCP1246 terminates the DRV signal based on the switch current. Thus, the NCP1246 always operates in current mode control so that the power MOSFET current is always limited ...
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... V > CCreset (V > V )*Latch +MaxDC)*t ILIM Figure 46. Operating Status Diagram for the Fully Latched Version A of the Device http://onsemi.com NCP1246 fault 16 ...
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... V > CCreset (V > BO MaxDC)*t ILIM Figure 47. Operating Status Diagram for the Autorecovery Version B of the Device http://onsemi.com NCP1246 )*Latch ON autorec fault 17 ...
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... CC brownïout condition prevent the controller from stopping during load transients when the V . The HV(start) The NCP1246 accepts a supply voltage as high with reaches CC(on) an overvoltage threshold V off. HV current ...
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... There is only one condition for which the current source doesn’t turn on when V reaches V CC voltage on HV pin is too low (below V HV Sensing of Rectified AC Voltage The NCP1246 features on its HV pin a true ac line monitoring circuitry. It includes a minimum startï HV(start) ...
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... X2 Cap Discharge Feature The X2 capacitor discharging feature is offered by usage of the NCP1246. This feature save approx – input power depending on the EMI filter X2 capacitors volume and it saves the external components count as well. The discharge feature is ensured via the startïup current source with a dedicated control circuitry for this function ...
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... Figure 50. The ac Line Unplug Detector Structure Used for X2 Capacitor Discharge System Figure 51. The ac Line Unplug Detector Timing Diagram NCP1246 http://onsemi.com 21 ...
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... Figure 52. The ac Line Unplug Detector Timing Diagram Detail with Noise Effects http://onsemi.com NCP1246 22 ...
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... Figure 53. HV Pin ac Input Timing Diagram with X2 Capacitor Discharge Sequence When the Application is Unplugged Under Extremely Low Line Condition NCP1246 http://onsemi.com 23 ...
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... The controller can only CC start, if the FB pin voltage increases above the 2.2 V level. See Figure 55 for timing diagrams. NCP1246 Unplugged Under High Line Condition Only the X2 cap discharge and SelfïSupply features is enabled in the low consumption off mode. The X2 cap discharging feature is enable due the safety reasons and the Selfï ...
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... Figure 55. Startïup, Shutdown and AC Line Unplug Time Diagram Oscillator with Maximum On Time and Frequency Jittering The NCP1246 includes an oscillator that sets the switching frequency 65 kHz or 100 kHz depending on the version. The maximum on time is 12.3 ms (for 65 kHz version (for 100 kHz version) with an accuracy of ± ...
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... When the FB voltage reaches V skip(in) skip mode is activated: the driver stops, and the internal consumption of the controller is decreased. While V NCP1246 frequency foldback mode to provide the natural transformer core antiïsaturation protection. The frequency jittering is still active while the oscillator frequency decreases as well. ...
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... Clamped Driver The supply voltage for the NCP1246 can be as high but most of the MOSFETs that will be connected to the DRV pin cannot accept more than their gate. The driver pin is therefore clamped safely below 16 V. This driver has a typical capability of 500.0 mA for source current and 800 mA for sink current. Currentï ...
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... NCP1246 Figure 60. SoftïStart Feature In order to allow the NCP1246 to operate in CCM with a duty cycle above 50%, the fixed slope compensation is internally applied to the currentïmode control. The slope appearing on the internal voltage setpoint for the PWM comparator is ï ...
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... OUT SW 2 NCP1246 Unfortunately, due to the inherent propagation delay of the logic, the actual peak current is higher at high input voltage than at low input voltage, leading to a significant difference in the maximum output power delivered by the power supply (eq http://onsemi ...
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... But this offset is unwanted to appear when the current sense signal is small, i.e. in light load conditions, where it Figure 64. Overpower Protection Current Relation to Feedback Voltage NCP1246 would be in the same order of magnitude. Therefore the compensation current is only added when the FB voltage is higher than V ...
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... A 3 bit A/D converter with the peak detector senses the ac input, and its output is periodically sampled and reset, in order to follow closely the input voltage variations. The NCP1246 sample and reset events are given by the V comparator used for sampling detection for the ac line input. ...
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... B), the controller tries to restart after t . Other possibilities of the latch autorec Figure 67. Overpower Compensation Timing Diagram NCP1246 release are the brownïout condition or the V reset. The timer is reset when the CS setpoint goes back below V before the timer elapses. The fault timer is also ILIM started if the driver signal is reset by the maximum on time ...
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... CC(ovp) Brownïout HV timer V < HV(stop timer Internal TSD Off mode 150 ms timer V < OFF NCP1246 Next Device Status Release to Normal Operation Mode Latch Latch Latch Latch Latch Latch Device stops (V HV Device stops, HV startï current source stops ...
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... V CC(on) V CC(min) Figure 68. Latched TimerïBased Overcurrent Protection (Option A) NCP1246 http://onsemi.com 34 ...
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... V CC(on) V CC(min) Figure 69. TimerïBased Protection Mode with Autorecovery Release from Latchïoff (Option B) NCP1246 http://onsemi.com 35 ...
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... SSTART min NTC(SSTART) min + C LATCH max V clamp0 min NCP1246 Figure 70. Latch Detection Schematic Reset occurs when a brownïout condition is detected or the V is cycled down to a reset voltage, which in a real CC application can only happen if the power supply is unplugged from the ac line. ...
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... V CC(on) V CC(min) Temperature Shutdown The NCP1246 includes a temperature shutdown protection with a trip point typically at 150°C and the typical hysteresis of 30°C. When the temperature rises above the high threshold, the controller instantaneously, and goes to the off mode with extremely ORDERING INFORMATION Ordering Part No ...
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... G 1.27 BSC 0.050 BSC J H 0.10 0.25 0.004 0.010 J 0.19 0.25 0.007 0.010 K 0.40 1.27 0.016 0.050 0.25 0.50 0.010 0.020 S 5.80 6.20 0.228 0.244 1.270 0.050 mm inches ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative NCP1246/D ...