ISOLATED_FEEDBACK_POWER_SUPPLY

Published:2009/7/9 2:37:00 Author:May | From:SeekIC

Figure 73-4 is a power supply circuit using the isolated feedback capabilities of the TL3103 for both current and voltage sensing. This supply is powered from the ac power line and has an output of 5 V at 1.5 A. Both output voltage and current are sensed and the error voltages are applied to the error amplifters of the TL594 PWM control IC. The 24-V transformer produces about 35 V at the 1000-μF filter capacitor. The 20-kHz switching frequency is set by the 6-KΩ resistor and the 0.01-μF capacitor on pins 6 and 5, respectively. The TL594 is set for push-pull operation by typing pin 13 high. The 5-V reference on pin 14 is tied to pin 15, which is the reference or the current error amplifier. The 5-V reference is also tied to pin 2 which is the reference for the output voltage error amplifier. The output voltage and current limit are set by adjustment of the 10-KΩ pots in the TL3103 error-sensing circuits. A pair of TIP31E npn transistors are used as switching transistors in a push-pull circuit.



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