NCP1028 ON Semiconductor, NCP1028 Datasheet
NCP1028
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NCP1028 Summary of contents
Page 1
... Medium Power Offline SMPS Featuring Low Standby Power The NCP1028 offers a new solution targeting output power levels from a few watts 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 ...
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... Feedback Signal Input 5 Drain Drain Connection - - 7 OPP Over Power Protection 8 GND The IC Ground NCP1028 NCP1028 Ramp Comp.* Figure 1. Typical Application This pin is connected to an external capacitor of typically 22 mF. To extend the duty cycle operation in Continuous Conduction Mode (CCM), pin 3 offers the ability to inject ramp compensation in the controller. If unused, short this pin to V ...
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... V CC Reset IBO + VBO 65 kHz or 100 kHz CLOCK Jittering V dd Icomp Ramp Comp. 25 Skip + - V dd RFB FB Figure 2. Internal Block Diagram NCP1028 IC1 UVLOs V CC Mngt 4 V rst Fault LEB Timer Ip Flag UVLO Soft-Start + Max Ip Selection ...
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... Offset Voltage above VCC at which the Internal Clamp Activates ON V Voltage at which the Internal Latch is Reset CC Internal IC Consumption, MOSFET Switching at POWER SWITCH CIRCUIT Power Switch Circuit On-State Resistance NCP1028 (Id = 100 mA 25° 125°C J Power Switch Circuit and Startup Breakdown Voltage = 120 mA, T (ID = 25° ...
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... 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. NCP1028 (For typical values T = 25°C, for min/max values T ...
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... TEMPERATURE (°C) Figure 4. 1.8 1.6 1.4 1.2 1.0 - TEMPERATURE (°C) Figure 6. NCP1028 100 TEMPERATURE (°C) Figure 3. 0.24 0.22 0.20 0.18 0.16 0.14 100 120 140 -20 0 900 850 800 750 700 650 600 550 500 450 400 350 -20 0 100 120 140 http://onsemi.com ...
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... TEMPERATURE (°C) Figure 8. 120 100 -40 - TEMPERATURE (°C) Figure 10. 610 600 590 580 570 560 550 540 530 520 510 - TEMPERATURE (°C) Figure 12. NCP1028 71.0 70.0 69.0 68.0 67.0 66.0 65.0 64.0 63.0 62.0 61.0 60.0 59.0 100 120 140 -20 0 87.0 85.0 83.0 81.0 79.0 77.0 75.0 80 100 120 140 -20 0 13.0 12.5 12.0 11.5 11.0 10.5 10.0 9.5 9.0 100 ...
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... TEMPERATURE (°C) Figure 16. 400 380 360 340 320 300 280 260 240 220 200 - TEMPERATURE (°C) Figure 18. NCP1028 100 120 140 - Ipin 100 120 ...
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... TEMPERATURE (°C) Figure 20. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10 Figure 22. Ipeak Reduction = F(lopp, @ temperature) NCP1028 100 100 120 140 -20 0 85°C 125°C 140°C -40 °C 25°C -20 °C 50 100 150 200 IOPP (mA) http://onsemi ...
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... Introduction The NCP1028 offers a complete current-mode control solution and enhances the NCP101X series. The component integrates everything needed to build a rugged and low-cost Switch-Mode Power Supply (SMPS) featuring low standby power. • Current-Mode Operation: The controller uses a current-mode control architecture, which, together ...
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... Startup Sequence The NCP1028 includes a high-voltage startup circuitry, directly deriving current from the bulk line to charge the Vbulk 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 V capacitor ...
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... V, the source smoothly transitions to IC2 and delivers its nominal value result, in case of short-circuit between V and GND, the power dissipation CC 650 m = 240 mW. Figure 25 portrays will drop to 370 this particular behavior. NCP1028 voltage evolution versus time bring startup ). Therefore, CC1 CC CC Figure 25 ...
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... As soon as the peak current setpoint reaches its maximum (during the startup period but also anytime an overload occurs), an internal error flag is asserted, Ipflag, indicating Figure 26. In case of short-circuit or overload, the NCP1028 protects itself and the power supply via a low frequency burst mode. The V NCP1028 ...
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... Some situations exist where an output short-circuit make the auxiliary winding collapse Figure 27. The auxiliary winding collapses in presence of a short-circuit. Pulses are immediately stopped as V NCP1028 is still alive, before the timer completion. In this particular case, the CC Undervoltage Lock Out (UVLO) circuitry has the priority and safely cuts off all driving pulses ...
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... Figure 28. In this particular case, the output goes low but the timer is not started since the FB pin is still held by the optocoupler. Due to the UVLO circuit, the controller safely stops operation at V NCP1028 reason, the controller becomes un-able to detect a real output short-circuit since Ipflag will never be asserted. ...
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... Fault Condition – Low Input Voltage The NCP1028 includes a brown-out circuitry able to protect the power supply in case of low input voltage conditions. Figure 29 shows how internally the NCP1028 monitors the voltage image of the bulk capacitor. Below a given level, the controller blocks the driving pulses, above it, it authorizes them ...
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... Latchoff Protection There are some situations where the converter shall be fully turned-off and stay latched. This can happen in the NCP1028 2 /3.018 Meg = when V reaches V CC sequence ...
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... In Figure 31 blocked and does not bother the BO measurement as long as the NTC and the optocoupler are not activated. As soon as the secondary optocoupler senses an OVP condition, or the NTC reacts to a high ambient Figure 32. If the BO pin is lifted up to VLATCH, the controller permanently latches off. NCP1028 V Vbulk CC + ...
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... SMPS entering deep standby (output un-loaded). Thus, care must be taken when clamp Figure 33. A more detailed view of the NCP1028 offers better insight on how to properly wire an auxiliary winding. R Since shall not bother the controller in standby, e.g. limit keep V to around 8 ...
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... Clearly speaking, it can take up to 100 ns for the NCP1028 current sense comparator to propagate through the various logical gates before reaching the power switch and finally shutting it off. ...
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... W at high line. Compared to our 735 mA, we need to decrease the V setpoint by 6% roughly when equals 350 Vdc. in The NCP1028 hosts a special circuitry looking at the couple voltage/current present on pin 7. Figure 36 shows how to arrange components around the controller to obtain Over Power Protection. OPP Over Power ...
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... In case no ramp compensation is required, pin 2 must be tied to V (eq. 9) Soft-Start The NCP1028 features a 1.0 ms soft-start, which reduces the power-on stress, but also contributes to lower the output overshoot. Figure 39 shows a typical operating waveform. The NCP1028 features a novel patented structure which offers a better soft-start ramp, almost ignoring the startup pedestal inherent to traditional current-mode supplies ...
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... Jittering Frequency jittering is a method used to soften the EMI signature by spreading the energy in the vicinity of the main switching component. The NCP1028 offers a "6% deviation of the nominal switching frequency. The sweep 61.1kHz Figure 40. Modulation Effects on the Clock Signal by the Skip-Cycle Skip cycle offers an efficient way to reduce the standby power by skipping unwanted cycles at light loads ...
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... V/3.0 A Universal Mains Power Supply Due to its low R , the NCP1028 can be used in DS(on) universal mains SMPS continuous power, provided that the chip power dissipation is well under control. That is to say that average power calculations and measurements have been carried and correlated. The ...
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... MOSFET. After evaluating the leakage inductance, you can compute C with Equation 15. Typical values are between 100 pF and up to 470 pF. Large capacitors increase capacitive losses… NCP1028 If we take the maximum R temperature, i. then conduction losses worse case are: P cond + rms R ds(on) + 571 mW 6 ...
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... The secondary side features an additional LC filter needed NCP1028 Power Dissipation and Heatsinking The NCP1028 hosting a power switch circuit and a controller mandatory to properly manage the heat generated by losses precaution is taken, risks exist to and V are trigger the internal thermal shutdown (TSD) ...
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... NCP1028 Figure 46. 5.0 V-3.0 A Universal Mains Power Supply http://onsemi.com 27 ...
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... Transformer Specifications: Vout = 5.0 V/3.0 A Vaux = 20 V/ 3.8 mH Ip, rms = 280 mA Ip, max = 800 mA Isec, rms = 5.0 A Fsw = 65 kHz Np:Nsec = 1 : 0.052 Np:Naux = 1 : 0.208 NCP1028 http://onsemi.com 28 ...
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... H G 0.13 (0.005) The product described herein (NCP1028), may be covered by one or more of the following U.S. patents: 5,418,410; 5,477,175; 6,271,735; 6,362,067; 6,385,060; 6,429,709; 6,448,625; 6,492,679; 6,597,221; 6,633,193; 6,919,598; 6,940,320. There may be other patents pending. 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 ...