ncp1651 ON Semiconductor, ncp1651 Datasheet
ncp1651
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ncp1651 Summary of contents
Page 1
... NCP1651 can help provide excellent power factor while limiting the peak primary current. Also, the fixed frequency operation eases the input filter design. The NCP1651 uses a proprietary multiplier design that allows for much more accurate operation than with conventional analog multipliers. ...
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... NOTE: Pins 14 and 15 have not been used for clearance considerations due to the potential voltages present on pin 16. In order to maintain proper spacing between the high voltage and low voltage pins, traces should not be placed on the circuit board between pins 16 and 13. NCP1651 Description http://onsemi.com ...
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... A. This device series contains ESD protection and exceeds the following tests: Pins 1−6: Human Body Model 2000 V per MIL−STD−883, Method 3015. Pins 1−6: Machine Model Method 200 V. Pin 8 is the HV startup to the device and is rated to the maximum rating of the part, or 500 V. NCP1651 Symbol V −0 ...
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... Ac Input (p−input) (Note 1) Offset Voltage (a−input) Multiplier Gain ramp pk ) (Note 1) AC INPUT (Pin 5) Input Bias Current (Total bias current for reference multiplier and current compensation amplifier) (Note 1) 1. Verified by design. NCP1651 (Unless otherwise noted volts kW − V ...
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... Line Pin Leakage (pin 16, Startup Circuit Inhibited 400 + +125 C A TOTAL DEVICE Operational Bias Current (C = 1.0 nF, f L(Driver) Bias Current in Undervoltage Mode 2. Verified by design. NCP1651 (continued) (Unless otherwise noted > 0 Increasing) – 100 kHz) osc http://onsemi.com ...
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... V−I CONVERTER A REFERENCE 0.75 V MULTIPLIER AC INPUT REF 4 COMP − AVERAGE CURRENT COMPENSATION GND 2 RAMP COMP NCP1651 16 STARTUP REFERENCE REGULATOR UVLO + − 8 COUNTER SHUTDOWN 0. OVER− TEMPERATURE SENSOR AC REFERENCE BUFFER + line in ref 4 V V−I − ...
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... GND FB/SD 0.5 V GND OSCILLATOR RAMP OSCILLATOR BLANKING PULSE 9.8 V OFF STARTUP ENABLE ON MAX OUTPUT CURRENT 0 FB/SD 0 SHUTDOWN STARTUP Figure 3. Divide−by−Eight Counter Timing Diagram NCP1651 Figure 2. Switching Timing Diagram CURRENT LIMIT http://onsemi.com SHUTDOWN ...
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... V (V) CC Figure 6. Bias Current in Shutdown Mode 100 STARTUP PIN VOLTAGE (V) Figure 8. Startup Current versus High Voltage NCP1651 12 10 PIN 400 500 0 200 Figure 5. FB/SD V−I Characteristics 5.0 − 4 4.0 125 C 3 ...
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... AC INPUT (V) Figure 12. Reference Multiplier Gain 100 1000 100 1 10 FREQUENCY (kHz) Figure 14. C versus Frequency T NCP1651 Typical Performance Characteristics 1.5 TURN−ON 1.0 TURN−OFF 0 100 125 0 Figure 11. FB/SD Clamp Voltage versus V 1000 2.5 V 2.0 V 100 1 1 ...
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... FREQUENCY (kHz) Figure 16. Maximum Duty Cycle versus Frequency 2.0 ms/div Figure 18. Transient Response for 6.5 Volt Reference NCP1651 10,000 FALL TIME 1000 100 250 300 0 50 100 10% TO 90% DRIVE RISE AND FALL TIMES Figure 17. Capacitance versus 10% to 90% Drive Rise and Fall Times ...
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... TND308/D) 4.12 NOTE: Valley Voltage is Zero 4.10 4.08 4.06 4.04 −50 − TEMPERATURE ( C) Figure 20. Peak Ramp Voltage versus Temperature 1 0.8 0.6 0.4 0.2 0 −50 NCP1651 Typical Performance Characteristics 6.52 6.50 6.48 6.46 6.44 75 100 125 0 NO LOAD 10 kW 3.3 kW − TEMPERATURE ( C) Figure 22 Shutdown Condition ref http://onsemi ...
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... NCP1651 FB/SD 9 680 SHUT DOWN 5 AC INPUT (Allows external converters to be synchronized to the switching frequency of this unit.) Figure 23. External Shutdown Circuit 33 k BAS16LT1 MMBT2907AL 0.33 mF Figure 24. Soft−Start Circuit http://onsemi.com 6.5 V 3.8 k V−I CONVERTER A REFERENCE MULTIPLIER V ref 12 AC COMP 11 NCP1651 ...
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... DC−DC converter lower component count which reduces the size and the cost of the power supply. The NCP1651 can operate in either the Continuous or Discontinuous Mode of operation, the following analysis will help to highlight the advantages of Continuous versus Discontinuous Mode of operation ...
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... P = 1.414 85 sin 90 5.18 ms/100 The results show that the peak current for a flyback converter operating in the Continuous Conduction Mode is NCP1651 one half the peak current of a flyback converter operating in the Discontinuous Conduction Mode. input) Continuous Conduction Mode rms A second result of running in DCM can be higher input current distortion, EMI, and a lower Power Factor, in comparison to CCM ...
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... CCM operation. 3. Following key governing equations have been incorporated in the design aid: PFC Operation The basic PWM function of the NCP1651 is controlled by a small block of circuitry, which comprises the DC regulation loop and the PFC circuit. These components are shown in Figure 30. ...
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3.8 k FB/SD 8 680 V−I REFERENCE CONVERTER MULTIPLIER AC INPUT V + line .75 9 − AVERAGE CURRENT COMPENSATION DRIVER 4 V − PWM + Logic PWM V error(ac) AC ERROR AMP V ref V ...
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... Since the input current has a fundamental frequency that is twice that of the line, the output filter must have poles NCP1651 lower than the input current to create a reasonable DC waveform. The DC output voltage is compared to a reference voltage by a secondary side error amplifier, and the error signal out of the secondary side amplifier is fed back into the Feedback input through an optocoupler ...
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... The DC reference is fed into a buffer with a gain of 1.625 which creates a 6.5 volt supply. This is used as an internal voltage to power many of the blocks inside of the NCP1651 and is also available for external use. The 6.5 volt reference is designed to be terminated with at 0.1 mF capacitor for stability reasons ...
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... For a boost inductor with a variable input voltage, this will vary over the AC input cycle, and with changes in the input line. A di/dt chart is included in the design spreadsheet that is available for the NCP1651. For optimum load transient performance, the ramp compensation should equal the falling di/dt at 100% duty + cycle. For optimum line transient response, it should equal − ...
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... Any use of this signal should incorporate a high impedance buffer. NCP1651 Due to the required accuracy of the peak and valley ramp Current voltages, the NCP1651 is not designed to be synchronized Sense AC Ref to the frequency of another oscillator. Buffer ...
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... Set dominant which means that if both R and S are high the S signal will dominate and Q will be high, which will hold the power switch off. The NCP1651 uses a voltage mode Pulse Width Modulation scheme based on a fixed frequency oscillator. The oscillator outputs a ramp waveform as well as a pulse which is coincident with the falling edge of the ramp ...
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... If not, another cycle will begin. The waveforms for overload timeout are shown in Figure 3. Shutdown The NCP1651 has a shutdown circuit that can be used to inhibit the operation of the chip by reducing the FB/SD pin voltage to less than 0.6 volts. When a shutdown signal is issued, the output of the shutdown comparator goes low. This immediately ceases the operation of the unit by OR’ ...
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... If this occurs, the V capacitor value should be increased. CC NCP1651 Soft−Start Circuit The AC error amplifier has been configured such that a low output level will cause the output duty cycle zero. This will have the effect of soft− ...
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... ON Semiconductor provides a spread sheet that incorporates the relevant equations, and will calculate the bias components for a circuit using the schematic shown. Figure 38. Typical Application Schematic NCP1651 DESIGN GUIDELINES http://onsemi.com 24 ...
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... If you are designing your own transformer, the ON Semiconductor spreadsheet (NCP1651_Design.xls) that is available as a design aid for this part can be of help. Enter various values of inductance as well as the turns ratio and observe the variation in duty cycle and peak current vs. ...
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... R This drives more current through the optocoupler, which in turn reduces the output of the converter. An alternate regulator is recommended, which is only slightly more expensive, and offers excellent protection from positive transients, and quick recovery from negative transients. NCP1651 C out 453 FB/SD 422 5.23 k Figure 42 ...
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... T di/dt secondary = di/dt reflected to the primary NCP1651 Simplifies to di/dt primary = di/dt secondary Equation 2) For proper slope compensation, the relationship between R and di/dt (primary ...
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... Where Pin 10 capacitance (F) 10 Where Ref gain pole freq (Hz) pole NCP1651 AC Error Amplifier The AC error amplifier is a transconductance amplifier that is terminated with a series R a pole−zero pair. To determine the values of R look at the two signals that reach the PWM inputs. The non− ...
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... Figure 42 is used, there are four resistors instead determine the gain of this circuit, R dc1 the upper two resistors, 9.31 k and 453 Ohms respectively, and R is the equivalent of the lower two resistors, 422 and dc2 5.23 k respectively. NCP1651 Loop Compensation R V ac1 ac 6 ...
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... The equation for the gain is good for frequencies below the pole. There is a single pole due to the output filter. Since the NCP1651 is a current mode converter, the inductor is not part of the output pole as can be seen in that equation. The modulator and output stage transfer functions have been split into two sets of equations ...
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... This solution will provide a phase margin of close practice the value of capacitance could be NCP1651 cut in half or more and probably remain stable. This can be tested in the circuit, or simulated with a model in SPICE or a similar analysis program ...
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... T M The product described herein (NCP1651), may be covered by U.S. patents including 6,373,734. Other patents may be 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. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC 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. “ ...