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Moteur de recherche de fiches techniques de composants électroniques |
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Moteur de recherche de fiches techniques de composants électroniques |
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TDA4863G Fiches technique(PDF) 10 Page - Infineon Technologies AG |
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TDA4863G Fiches technique(HTML) 10 Page - Infineon Technologies AG |
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10 / 27 page  TDA4863 Functional Description Data Sheet 10 V1.0, 2003-05 2.4 Overvoltage Regulator Because of the integrator´s low bandwidth fast changes of the output voltage can’t be regulated within an adequate time. Fast output changes occur during initial start-up, sudden load removal, or output arcing. While the integrator´s differential input voltage remains zero during this fast changes a peak current is flowing through the external capacitor into pin VAOUT. If this current exceeds an internal defined margin the overvoltage regulator circuitry reduces the multiplier output voltage. As a result the on time of the MOSFET is reduced. 2.5 Multiplier The one quadrant multiplier regulates the gate driver with respect of the DC output voltage and the AC half wave rectified input voltage. Both inputs are designed to achieve good linearity over a wide dynamic range to represent an AC line free from distortion. Special efforts have been made to assure universal line applications with respect to a 90 to 270 V AC range. The multiplier output is internally clamped to1.3 V. So the MOSFET is protected against critical operating during start up. 2.6 Current Sense Comparator, LEB and RS Flip-Flop The source current of the MOS transistor is transferred into a sense voltage via the external sense resistor. The multiplier output voltage is compared with this sense voltage. Switch on time of the MOS transistor is determined by the comparision result To protect the current comparator input from negative pulses a current source is inserted which sends current out of the ISENSE pin every time when V ISENSE-signal is falling below ground potential. An internal RC-filter is connected at the ISENSE pin which smoothes the switch-on current spike.The remaining switch-on current spike is blanked out via a leading edge blanking circuit with a blanking time of typ. 200 ns. The RS Flip-Flop ensures that only one single switch-on and switch-off pulse appears at the gate drive output during a given cycle (double pulse suppression). 2.7 Zero Current Detector The zero current detector senses the inductor current via an auxiliary winding and ensures that the next on-time of the MOSFET is initiated immediately when the inductor current has reached zero. This reduces the reverse recovery losses of the boost converter diode to a minimum. The MOSFET is switched off when the voltage drop of the shunt resistor exceeds the voltage level of the multiplier output. So the boost current waveform has a triangular shape and there are no deadtime gaps between the cycles. This leads to a continuous AC line current limiting the peak current to twice of the average current. |
Numéro de pièce similaire - TDA4863G |
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Description similaire - TDA4863G |
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