TOPSwitch--Ⅱ

Published:2011/4/21 21:08:00 Author:May | From:SeekIC

Pin arrangement of TOPSwitch --Ⅱ is shown in the diagram. It has three kinds of package. Among them, TO-220 package has heating panel and belongs to typical three-terminal device. Its shape is the same as 7800 series three-terminal linear regulators. DIP - 8 and SMD-8 package both has 8-pin package, but can be reduced to three; difference between the two is DIP-8 can be equipped with 8 pin IC socket, SMD-8 is surface patch and do not need to punch welding. Three pins of TOPSwitch - Ⅱ are control terminal C (Con-trol), source S (Source), drain D (Drain). TOPSwitch - Ⅱ internal block diagram is shown in below, it mainly includes 10 parts: (1) control voltage source; (2) band gap voltage reference; (3) oscillator; (4) shunt regulator / error amplifier; (5) pulse-width modulator; (6) gate driver stage and output stage; (7) over-current protection circuit; (8) Overheat protection and power-on reset circuit; (9) shutdown / auto-restart circuit; (10 ) high-voltage current source. In the diagram, Zc is control side of the dynamic impedance; RE is error voltage detection resistor; RA and CA make up low-pass filter with 7kHz cut off frequecny. The basic principle of TOPSwitch - Ⅱ is to use the feedback current Ic to adjust the duty cycle D, so as to achieve the purpose of regulation.



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