PDF NCP1028 Data sheet ( Hoja de datos )

Número de pieza	NCP1028
Descripción	High-Voltage Switcher
Fabricantes	ON Semiconductor
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No Preview Available ! NCP1028 High−Voltage Switcher for Medium Power Offline SMPS Featuring Low Standby Power The NCP1028 offers a new solution targeting output power levels from a few watts up to 15 W in a universal mains flyback application. Our proprietary high−voltage technology lets us include a power MOSFET together with a startup current source, all directly connected to the bulk capacitor. To prevent lethal runaway in low input voltage conditions, an adjustable brown−out circuitry blocks the activity until sufficient input level is reached. Current−mode operation together with an adjustable ramp compensation offers superior performance in universal mains applications. Furthermore, an Over Power Protection pin brings the ability to precisely compensate all internal delays in high input voltage conditions and optimize the maximum output current capability. Protection wise, a timer detects an overload or a short−circuit and stops all operations, ensuring a safe auto−recovery, low duty cycle burst operation. Finally, a great RDS(on) figure makes the circuit an excellent choice for standby/auxiliary offline power supplies or applications requiring higher output power levels. Features • Built−in 700 V MOSFET with Typical RDS(on) of 5.w8wwW.Da,taTShJee=t4U2.co5m°C • Current−Mode Fixed Frequency Operation: 65 kHz and 100 kHz • Fixed Peak Current of 800 mA • Skip−Cycle Operation at Low Peak Currents • Internal Current Source for Clean and Lossless Startup Sequence • Auto−Recovery Output Short Circuit Protection with Timer−Based Detection • Programmable Brown−Out Input for Low Input Voltage Detection • Programmable Over Power Protection • Input to Permanently Latchoff the Part • Internal Frequency Jittering for Improved EMI Signature • Extended Duty Cycle Operation to 80% Typical • No−Load Input Standby Power of 85 mW @ 265 Vac • 500 mW Loaded, Input Power of 715 mW @ 230 Vac • These are Pb−Free Devices** Typical Applications • Medium Power AC−DC Adapters for Chargers • Auxiliary/Standby Power Supplies for ATX and TVS Power Supplies Reference 230 VAC 90−265 VAC NCP1028 − 5.8 W 25 W* 15 W* Typical values, open−frame, 65 kHz version, RqJA < 75°C/W, TA = 50°C. For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. http://onsemi.com MARKING DIAGRAM 8−LEAD PDIP P SUFFIX CASE 626A P1028Pxxx AWL YYWWG xxx = 65 or 100 A = Assembly Location WL = Wafer Lot YY = Year WW = Work Week G = Pb−Free Package PIN CONNECTIONS VCC Ramp Comp. Brown−Out FB GND OPP (Top View) Drain ORDERING INFORMATION Device Package Shipping NCP1028P065G PDIP−8 50 Units / Rail (Pb−Free) NCP1028P100G PDIP−8 50 Units / Rail (Pb−Free) *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. © Semiconductor Components Industries, LLC, 2007 January, 2007 − Rev. 0 1 Publication Order Number: NCP1028/D 1 page NCP1028 ELECTRICAL CHARACTERISTICS (continued) (For typical values TJ = 25°C, for min/max values TJ = 0°C to +125°C, Max TJ = 150°C, VCC = 8.0 V, unless otherwise noted.) Characteristic Pin Symbol Min Typ Max CURRENT COMPARATOR Maximum Internal Current Setpoint, Pin 4 Open, TJ = 25°C, FSW = 65 kHz (Note 3) − Ipeak_27_CS_ 720 65 k 800 880 Final Switch Current with a Primary Slope of 200 mA/ms, FSW = 65 kHz (Note 4) − Ipeak_27_SW_ − 65 k 820 − Maximum Internal Current Setpoint, Pin 4 Open, TJ = 25°C, FSW = 100 kHz (Note 3) − Ipeak_27_CS_ 720 100 k 800 880 Final Switch Current with a Primary Slope of 200 mA/ms, FSW = 100 kHz (Note 4) − Ipeak_27_SW_ − 100 k 820 − Setpoint Decrease for a Pin 7 Injected Current of 40 mA, TJ = 25°C Voltage Level in Pin 7 at which OPP Starts to Operate 7 IOPP − 23 − 7 IOPPtripV − 1.5 − Soft−Start Duration Propagation Delay from Current Detection to Drain OFF State Leading Edge Blanking Duration INTERNAL OSCILLATOR − TSS − 1.0 − − Tprop − 100 − − TLEB − 200 − Oscillation Frequency (Note 5) 65 kHz Version, TJ = 25°C − fOSC 58.5 65 71.5 Oscillation Frequency (Note 5) 100 kHz Version, TJ = 25°C − fOSC 90 100 110 Frequency Jittering in Percentage of fOSC Jittering Swing Frequency − fJitter − "6.0 − − fswing − 300 − Maximum Duty Cycle − Dmax 74 80 87 FEEDBACK SECTION Internal Pullup Resistor 4 Rupp − 16 − Ramp Compensation Level on Pin 1 – Rramp = 100 kW 2 Rlevel − 2.75 − SKIP CYCLE GENERATION Internal Skip Mode Level, in Percentage of Maximum Peak Current − Iskip − 25 − PROTECTIONS Brown−Out Level 3 VBO 510 570 620 Brown−Out Hysteresis Current, TJ = 25°C (Note 3) Brown−Out Hysteresis Current, TJ = 0°C to 125°C Fault Validation further to Error Flag Assertion 3 IBOhyste 10 11.5 13 3 IBOhyste − 10 − − TimerON 40 55 − OFF Phase in Fault Mode − TimerOFF − 440 − Latching Voltage on Brown−Out Pin 3 Vlatch 3.15 3.5 3.85 Latch Input Integrating Filter Time Constant 3 TdelBOL − 20 − TEMPERATURE MANAGEMENT Temperature Shutdown − TSD 160 − − Hysteresis in Shutdown − − − 40 − 3. See characterization curves for full temperature span evolution. 4. The final switch current is: Ipeak_2X_CS + Tprop x Vin / Lp, with Vin the input voltage and Lp the primary inductor in a flyback. 5. Oscillator frequency is measured with disabled jittering. Unit mA mA mA mA % V ms ns ns kHz kHz % Hz % kW V % mV mA mA ms ms V ms °C °C http://onsemi.com 5 5 Page NCP1028 Startup Sequence The NCP1028 includes a high−voltage startup circuitry, directly deriving current from the bulk line to charge the Vbulk VCC capacitor. Figure 23 details the simplified internal arrangement. I1 RVCC 1 ICC1 + IC1 ← 5 I2 Iclamp −+ + CVCC Vz = 8.7 V VCCon VCCoff + 8 Figure 23. Internal Arrangement of the Startup Circuitry When the power supply is first connected to the mains outlet, the internal current source is biased and charges up the VCC capacitor. When the voltage on this VCC capacitor reaches the VCCON level (typically 8.5 V), the current source turns off, reducing the amount of power being dissipated. At this time, the VCC capacitor only supplies the controller, and the auxiliary supply should take over before VCC collapses below VCC(min). This VCC capacitor, CVCC, must therefore be calculated to hold enough energy so that VCC stays above VCC(min) (7.3 V typical) until the auxiliary voltage fully takes over. An auxiliary winding is needed to maintain the VCC in order to self−supply the switcher. The VCC capacitor has only a supply role and its value does not impact other parameters such as fault duration or the frequency sweep period for instance. As one can see in Figure 23, an internal active Zener diode, protects the switcher against lethal VCC runaways. This situation can occur if the feedback loop optocoupler fails, for instance, and you would like to protect the converter against an over voltage event. In that case, the internal current increase incurred by the VCC rapid growth triggers the over voltage protection (OVP) circuit and immediately stops the output pulses for 440 ms. Then a new startup attempt takes place to check whether the fault has disappeared or not. The OVP paragraph gives more design details on this particular section. The VCC capacitor can be calculated knowing a) the amount of energy that needs to be stored; b) the time it takes for the auxiliary voltage to appear, and; c) the current consumed by the controller at that time. For a better understanding, Figure 24 shows how the voltage evolves on the VCC capacitor upon startup. http://onsemi.com 11 11 Page

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