Accompanying the development of times of science and technology, module power source gets market reception more greatly also, when use module power source, how should enhance the stability of module power source and dependability? A few fields are traversed below, electric capacity of input, output is received outside introducing how to be chosen, in order to promote module the stability of the service life of power source and whole power supply system, reliability.

 

In the actual application of module power source, electric capacity of input, output receives outside choose often meet from proceed with of a few respects:

  •Rated compression is worth capacitance.

  •The look of capacitance is worth.

  •The service life of capacitance.

 

How dot of key introduction 1~2 chooses electric capacity of input, output below.

 

 

1, in application of DC-DC power source, the compression that input capacitance receives outside is worth us to be able to choose 1.3-1.4 commonly times compression.

 

For example: The compression of filter wave capacitance that then for 48V we choose is worth input voltage to be 63V. The power source that the reason is DC-DC starts electric current big, cause impact easily 2 times voltage is exorbitant, damage thereby parts of an apparatus.

 

2, value of compression of capacitance of wave of AC-DC commutate filter chooses: In circuit of wave of AC-DC commutate filter, according to formula we can be calculated the size of the academic volts d.c. after giving rectification.

 

For example: In the rectification circuit that inputs 90-265Vac, can reach through formulary computation the voltage limits after rectification is in 127-375Vdc. According to experience we can choose compression to be worth the capacitance that in 1.1-1.3 voltage of times theoretical calculation is worth commonly, consideration cost factor has some of architect to also can consider

 

The capacitance that voltage of 1 times theoretical calculation is worth.

 

 

In a lot of document, to C of filter wave capacitance choose, much use experience is formulary, think C of filter wave capacitance has been jumped over greatly more; In the maintenance of circuit of wave of a few filter, technical personnel often uses larger than former circuit capacity electric capacity to replace broken already electric capacity. If pursue a circuit of shown wave of simple commutate filter.

 

Graph circuit of equivalent of 1 input, output
 

From theoretic tell, the weaveform that the capacity of C of filter wave capacitance in increasing circuit can make output voltage really becomes more flowing, rise and fall smaller, but put through in circuit the instant, the impulse current ingredient that produces in circuit however cannot by oversight; Right in the maintenance of circuit of wave of a few filter of filter wave capacitance replace the issue that also is put in impulse current, changing below the premise of other component, pure the size that increases filter wave electric capacity can make the real service life of whole circuit shortens greatly, even burn down is whole circuit. Besides, the size that increases filter wave electric capacity purely also is finite to improving the function that outputs voltage. Do the voltaic curve when the volume that different input capacitance receives outside a simple test is started, following plan institute are shown capacitance size and the relation curve of the electric current that start are received outside be an input.

 

 

From this the curve is OK the input is received outside seeing electric capacity is larger, the electric current that start is bigger, those who accompany is bigger also to the impulse current in circuit. Bigger and bigger also to the menace of whole circuit.

 

 

Pursue on the starting electricity that capacitance size receives to differ outside be is undee. Capacitance is received to be below particular case outside, the electric current that start reachs lowermost value, to the input of whole circuit, output environment has very big improvement. Capacitance is received to exceed this limits to be able to bring about the electric current that start to increase outside becoming, also increase subsequently to the menace of other parts of an apparatus, bring about appear the attaint of parts of an apparatus of different level.

 

 

Output capacitance choose, the outputs ripple noise and power source laden ability that the element of general consideration is power source (the load that allow a gender) . Below the condition that allows in cost, a lot of people are met capacitance of output filter wave is being received outside thinking is bigger, can reduce ripple noise interference, more firm to systematic power supply, this is a kind of wrong idea.

 

Of the capacitance that outputs filter wave choose, not be factor of consideration ripple noise only, the starting ability that considers module power source even and bear the ability that inputs impulse current. Following plan institute show: It is a product that delivers far module to output 25w, the weaveform of input electric current that receives size look to be worth different situation to fall outside output and output ripple noise pursue.

 

 

The input that test of 470uf of output electric capacity receives outside outputs undee graph
 

The input that test of 4700uf of output electric capacity receives outside outputs undee graph
 

From the graph data can see, it is certain that output electric capacity is received to allow a value to be in outside size when reduce effect to arriving since ripple noise, but as outside increase ripple noise what receive capacitance to be able to be in value of a balance ceaselessly. Watch weaveform of input electric current instead, in output capacitance increases a circumstance when next starting, input electric current is maintained can grow more in time of big electric current. If use module fights an input impulse current is small, bring about module possibly to suffer impulse current below proper time so too big and attaint. Output electric capacity is being received beyond place also is not bigger better, this should be mixed according to the starting ability of module bear voltaic concussion capacity comes of make choice of.

 

 

Reasonable in the use process of module power source outside a kind of protection that receiving electric capacity of input, output is pair of module module capacitance, also improved the service life of power source greatly at the same time, reduced the needless hidden trouble that input, output is not stabilized and brings whole job system existence because of power source.

 

ZLG extends the advantage of module of far power source: Product of module of far power source is delivered in us in the specification, we can recommend most appropriate periphery in detail to the client circuit and outside the volume holding a cost that receives capacitance, effective assurance the optimal environment that module leaves in applied circumstance, also assured the security that the client uses and dependability at the same time. Because of,avoided outside receive capacitance type selecting incorrect the loss that brings module and whole system. Following plan institute are shown is to send the periphery circuit of far module double output to recommend graph and outside receive capacitance size value.

 

 

Input power source for further stability, in the input end increases one capacitance Cin, if output ripple and noise to be reduced further, the capacitance Cout with small impedance of equivalent of one series connection can increase in output end, but the biggest load allowing a gender that allows a value to cannot exceed this product, can cause power source module to start otherwise undesirable. Capacitance value is received outside recommending, if express,1 is shown.

 

Watch 1 capacitance value is received outside recommending