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1、DC Switching Power Supply Protection Technology Posted:2006-2-26 10:57:00 visit:665 chinese Version Related NewsAbstract: The DC switching power supply protection system is proposed to protect the system design principles and machine protection measures, analysis of switching power supply in the ran
2、ge of protected characteristics and design method, introduced several practical protection of circuit. Keywords: switching power supply protection circuit system design 1 Introduction DC switching regulator used in the price of more expensive high-power switching devices, the control circuit is also
3、 more complex, In addition, the load switching regulators are generally used a large number of highly integrated devices installed electronic systems. Transistors and integrated device tolerance of electricity, less heat shocks. Thus switching regulator should take into consideration the protection
4、of voltage regulators and load their own safety. Many different types of protection circuits introduced here polarity protection, program protection, over-current protection, over-voltage protection, under voltage protection and thermal protection circuits. Several protection methods are usually cho
5、sen to be combined to form a comprehensive protection system. 2 Polarity Protection DC switching regulators input are generally not regulated DC power supply. Due to operational errors or unforeseen circumstances will be the wrong polarity, switching power supply will be damaged. Polarity protection
6、 purposes, is to make the switching regulator only when the correct polarity is not regulated to DC power supply when connected to work. The use of a single wizard-pass device can achieve the power supply polarity protection. As the diode D to flow through the switching regulators input total curren
7、t, so this circuit applied in a low-power switching regulators on the more appropriate. Power in the larger occasion, put the polarity protection circuit as a program to protect a link, eliminating the need for high power required for polarity protection diodes, power consumption will be reduced. Fo
8、r convenient operation, easy to identify the polarity right or wrong。3 process protections Switching power supply circuit more complicated, basically can be divided into a low-power control section and power switch part. Belong to high-power switching transistor, in order to protect the switching tr
9、ansistor is turned on or off the power when the security must make the modulators, amplifiers and other small power control circuit. To this end, to ensure that the correct boot process. Switching regulators input generally received a small inductance and large capacitance of the input filter. In th
10、e boot an instant, filter capacitor will flow through the large surge current, the inrush current can be several times the normal input current. Make such a large surge current ordinary power switch contact or relay contact melting, and to enter the fuse fuse. In addition, the surge current can also
11、 damage the capacitor, so that shortened life expectancy, premature damage. To this end, the boot should be access to a current-limiting resistor, through which current-limiting resistor to charge the capacitor. In order not to make the current-limiting resistors consume excessive power, thereby aff
12、ecting the normal operation of switching regulators, and in the boot after the end of the transient process, with an automatic relay shorted it, so that DC power directly to the switching regulator power supply。Switching regulator control circuit of the logic components or operational amplifiers nee
13、d to use auxiliary power supply. For this reason, auxiliary power must be on the switch circuit. This can be the boot process control circuitry to be guaranteed. Normal boot process are: identification of the polarity of input power, voltage protection - the boot process circuit - auxiliary power su
14、pply through current-limiting resistor R of the switching regulators input capacitor C charge - the modulation switching regulator circuit, short-circuit current-limiting resistor - switching regulator stability. In the switching regulator, by just getting on its machines, because of its large outpu
15、t capacitance, charge to the rated output voltage take some time. During this time, the sampling amplifier input and low output voltage sampling, according to the system characteristics of the closed-loop regulation will force the switch transistor conduction time longer, this way, the switching tra
16、nsistor during this period will tend to continuous conduction, and easily damaged. To this end, requests the boot this period of time, switching modulation circuit output to the switching transistor base of the pulse-width modulated drive signals, which would ensure switching transistor deadline to gradually normalize the switching state and therefore I need to create boot protection to meet the soft - Start. 4over-current protecti
