What is the impedance of the switching power supply module
Switch power supply module impedance is refers to the internal resistance, capacitance, and inductance circuit consisting of a block of alternating current (ac).
The impedance of the resistor is itself, capacitance inductance both block called reactance of alternating current (ac).
Capacitance of an alternating current in the circuit block call capacitive reactance, the greater the alternating current frequency, the smaller the capacitive reactance, has a direct hand in the role of isolation.
Inductance of an alternating current in the circuit block is called impedance, the greater the frequency of alternating current (ac), the greater the impedance, with dentsu straight on communication in isolation, filtering can be performed.
Power supply module resistance than convention against work load voltage regulation circuit, any changes will lead to serious load current module output of the ups and downs, ups and downs of the test and the influence of the pulse and the influence of noise is the result of the test.
When the line voltage or load current changes, output voltage of dc power supply module will be ups and downs.
Voltage stability degree by regulating circuit parameters, filter capacitance and the energy release rate are determined, stable size is no load or full load value when the percentage of the output voltage or change.
Transient response and recovery time is in commonly 10% load change, the commonly used output deviation peak output voltage on the number of millivolt calibration deviation, marked by output recovered to normal millivolt used for recovery time.
Power module transient response and recovery time show that the size of the output when a sudden change in load, regulating circuit the size of the normal voltage ability, is generally used when the load suddenly changes the output of the deviation value or output back to the original time used for calibration.
Impedance matching can adjust the load power and suppress reflection signal, the signal source or transmission line and the load to achieve appropriate collocation is called impedance matching.
Or low frequency circuit for a pure resistance, capacitance inductance reactance value of the basic can be ignored, main source impedance circuit resistance.
In the field of high frequency, when the signal wavelength and long transmission lines in the same order of magnitude, the reflected signal and the original signal aliasing, and impedance matching can be eliminated effectively reduce high frequency signal reflection.
PCB line impedance mainly from parasitic capacitance, inductance and resistance, there are material dielectric constant factors, line width, line thickness and the thickness of the bonding pad, etc.
In the field of high frequency signal frequency had a great influence on PCB go line impedance values, when the time is less than 1 ns digital signal edge or analog signal frequency more than 300 m will be thinking about the impedance.
The impedance matching method mainly has change resistance or adjust the transmission line two kinds.
Change resistance refers to by the series of parallel capacitor, inductor and load adjusting load impedance value, to reach the source and load impedance matching.
Adjust the transmission line is lengthen the distance between the source and load, cooperate to adjust resistance capacitance inductance is zero.
Target impedance switch power supply is the power system transient impedance, and a certain width of band, under the same conditions, the greater the frequency of power system, the greater the impedance.
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