ncp1251 ON Semiconductor, ncp1251 Datasheet
ncp1251
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ncp1251 Summary of contents
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... Current-Mode PWM Controller for Off-line Power Supplies The NCP1251 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a tiny TSOP−6 package. With a supply range the controller hosts a jittered 65 kHz or 100 kHz switching circuitry operated in peak current mode control ...
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... OPTIONS Controller NCP1251ASN65T1G NCP1251BSN65T1G NCP1251ASN100T1G NCP1251BSN100T1G ORDERING INFORMATION Device Package Marking NCP1251ASN65T1G 5AA NCP1251BSN65T1G 5A2 NCP1251ASN100T1G 5AC NCP1251BSN100T1G 5AD †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/ ...
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OP P Vlatch Up OVP RST gone? 4 VDD R Frequency modulation Frequency foldback Vfold Vskip vdd RFB / 4 LEB Figure 2. Internal Circuit Architecture IpFlag UVLO Vcc and logic management 600 ns time constant vd d ...
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MAXIMUM RATINGS TABLE Symbol V Power Supply voltage Maximum DRV pin voltage when DRV in H state, transient voltage (Note 1) DRVtran Maximum voltage on low power pins CS, FB and OPP IOPP Maximum injected negative ...
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ELECTRICAL CHARACTERISTICS (For typical values T = 25°C, for min/max values T J Symbol CURRENT COMPARATOR V Maximum internal current setpoint – T Limit1 V Maximum internal current setpoint – T Limit2 V Default internal voltage set point for frequency ...
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TEMPERATURE (°C) Figure −50 − TEMPERATURE (°C) Figure 5. ...
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TEMPERATURE (°C) Figure 9. 19.9 19.4 18.9 18.4 17.9 17.4 16.9 16.4 15.9 −50 − TEMPERATURE (°C) Figure 11 ...
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kHz SW 1.5 1 0.5 0 −50 − TEMPERATURE (°C) Figure 15 −50 − TEMPERATURE (°C) Figure 17. 390 340 290 240 ...
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TEMPERATURE (°C) Figure 21. 100 −50 − TEMPERATURE (°C) Figure 23 ...
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TEMPERATURE (°C) Figure 27. 12.9 12.4 11.9 11.4 10.9 10.4 9.9 9.4 8.9 −50 − TEMPERATURE (°C) Figure 29. 1.9 1.8 1.7 1.6 1.5 1.4 1.3 ...
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TEMPERATURE (°C) Figure 33. 390 340 290 240 190 −50 − TEMPERATURE (°C) Figure 35. 160 150 140 130 120 110 100 90 ...
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TYPICAL CHARACTERISTICS 26.9 26.4 25.9 25.4 24.9 24.4 23.9 −50 − TEMPERATURE (°C) Figure 39. http://onsemi.com 12 75 100 125 ...
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... Current−mode operation with internal ramp compensation: Implementing peak current mode control at a fixed 65 kHz or 100 kHz, the NCP1251 offers an internal ramp compensation signal that can easily by summed with the sensed current. Sub harmonic oscillations are eliminated via the inclusion of a single resistor in series with the current− ...
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D2 1N4007 12 input mains D4 1N4007 Figure 40. The Startup Resistor Can Be Connected to the Input Mains for Further Power Dissipation Reduction The first step starts with the calculation of the V capacitor which will supply the controller ...
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SCR won’t remain latched. To build a sufficient design margin, we recommend to keep at least 60 mA flowing at the ...
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RoppU This p oin t will be adjusted to reduce the ref at hi line to the desired level. OPP oppL Figure 42. The OPP Circuitry Affects the Maximum Peak Current Set Point by Summing a ...
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Finally, please note that another comparator internally fixes the maximum peak current set point to 0.8 V even if the OPP pin is inadvertently biased above 0 V. Frequency Foldback The reduction of no−load standby power associated with the need ...
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... Figure 46. Inserting a Resistor in Series with the Current Sense Information Brings Ramp Compensation and In the NCP1251 controller, the oscillator ramp features a 2.5 V swing. If the clock operates kHz frequency, then the available oscillator slope corresponds to: vcc vcc vdrv ...
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In our flyback design, let’s assume that our primary is 770 mH, and the SMPS delivers 19 V with inductance ratio of 1:0.25. The off−time primary current slope thus given by: ...
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V. Under 3 mA and neglecting the series diode forward drop, it requires a series resistor of latch VOP OVP OVP OPPL In nominal conditions, ...
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NT C ROPPU 841k OP P ROPPL 2.5k Vlatch Figure 49. The Internal Circuitry Hooked to Pin 3 Can Be Used to Implement Over Temperature Protection (OTP) Back to our 19 V adapter, we have found that the plateau voltage ...
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... ROPPL 2.5k 5 Vlatch Figure 51. A Small RC Filter Avoids the Fast Rising Spikes from Reaching the Protection Pin of the NCP1251 in Presence of Energetic Perturbations Superimposed on the Input Line D2 1N4148 1 OVP OPP network. Typical values are those given in Figure 51 and must be selected to provide the adequate filtering function without degrading the stand− ...
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... Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5773−3850 http://onsemi.com 23 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° − ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative NCP1251/D ...