an8029 Panasonic Corporation of North America, an8029 Datasheet
an8029
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an8029 Summary of contents
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... Voltage Regulators AN8029 Self-excited RCC pseudo-resonance type AC-DC switching power supply control IC Overview The AN8029 developed for controlling the self-excited switching power supply employing the RCC pseudo-resonance type control method compact, equipped only with the necessary mini- mum functions. The maximum on-period and the minimum off-pe- riod can be set separately by using the external capacitor and resistor respectively ...
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... AN8029 Pin Descriptions Pin No. Symbol 1 TDL Transformer reset detection 2 TOFF Pin for connecting C and R to set minimum off-period 3 TON Pin for connecting C to set minimum on-period 4 CLM Input pin for overcurrent protection detection 5 GND Grounding pin 6 V Output pin OUT 7 V Power supply voltage pin ...
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... OFF TOFF: Terminal for connecting the resistor and capacitor for determining the minimum off-period (low) of the IC output (V OUT An equation for approximate calculation of the minimum off-period ( 2.2 C OFF C: External capacitance R: External resistance AN8029 Min Typ Max Unit 135 110 85 A 0.55 0.7 0.85 V 0.1 0.05 0 ...
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... AN8029 Terminal Equivalent Circuits (continued) Pin No. Equivalent circuit 3 V REF Comp. 0 REF Comp TON Terminal for connecting the capacitor for deter- mining the maximum on-period (high) of the IC output ( equation for approximate cal- OUT culation of the maximum on-period (T ...
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... It is possible to cancel about 180 mA of the dark current of photocoupler. After AC rectification Start resistance OUT GND Before start Start voltage Stop voltage . AN8029 Description I Start Voltage supplied a from bias coil Start condition b c Start failure Figure 1 ...
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... AN8029 Application Notes (continued) [1] Operation descriptions (continued) 1. Start/stop circuit block (continued) Start mechanism (continued) Since the supply voltage continuously decreases during the above period (area b in figure 1), the power supply is not able to start (state c in figure 1), if the stop voltage of the IC is reached before the sufficient supply voltage is supplied from the bias coil ...
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... Figure 4. Feedback current versus charge current characteristics 4. Pseudo-resonance operation (Power MOSFET turn-on delay circuit) For the AN8029, the pseudo-resonance operation becomes possible by making connection as shown in figure 5. The resonance capacitor, and the R9 and C9 constitute the delay circuit for regulating the turn-on of power MOSFET ...
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... AN8029 Application Notes (continued) [1] Operation descriptions (continued) 4. Pseudo-resonance operation (Power MOSFET turn-on delay circuit) (continued) As for the turn-on of power MOSFET, determine the delay time by selecting the constant of the R9 and C9 so that it turns on at 1/2 cycle of the resonance frequency simplified method, select so that the voltage waveform turns on at zero voltage. (Refer to figure 6) ...
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... Since such level fluctuation means the neces- sity for an increase in the withstanding capability of used parts and in the worst case it means the cause of destruction, the accuracy of detection level is increased as much as possible for the AN8029 (approximately 4%). 7. Overvoltage protection circuit (OVP) OVP is an abbreviation of over voltage protection ...
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... AN8029 Application Notes (continued) [1] Operation descriptions (continued) 7. Overvoltage protection circuit (OVP) (continued) Operating supply current characteristics While the OVP is operating, the decrease of the supply current causes the rise of the supply voltage V in the worst case, the guaranteed breakdown voltage of the IC (35 V) can be exceeded. In order to prevent the rise of supply voltage, the IC is provided with such characteristics as that the supply current rises in the constant resistance mode ...
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... GND. OVP V TH Figure 10. Timer latch basic operation 0.1 A (DC) and the current at peak is 1.0 A (Peak). The circuit is is under the stop voltage so that it turns off the CC AN8029 Power supply stop Time Power supply stop Time Power supply stop 7.3 V (typ.) Time ...
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... AN8029 Application Notes (continued) [2] Design reference data How to start the soft start function by external parts The power supply rises under overload condition due to the capacitor connected to the power supply output. In this condition, since the voltage of the power supply output is low, the normal constant voltage control attempts to rise the power supply output at the maximum duty ...
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... Voltage Regulators Application Circuit Example AN8029 GND TON FB TOFF 13 ...