Used very long diode, I think I know diode quite, but, the old asks me today:

 

(1) on the side of why carry power inductance in the output of DC-DC should be a diode added?

(2) why is have to diode has compared Xiaoteji?

 

The forehead, the forehead, “ commutate? ”“ stabilized voltage? Is ” still “ demodulation? ” I am messy. . . Good, I did not answer to come up …

 

So I do not know diode …

 

Then, had article, evil filling foundation, what instability goes is not far ah ~

 

1, ” of diode of He Wei “ ?

 

A diode is electric current one-way door (the commonnest in station of railway station pass in and out, can one-sided is current. . . ) , be opposite when the zincous photograph of diode at cathode voltage is when, call “ to slant buy ” , and this should is more than diode itself itself to bias voltage make what stuff place decides guide electrify is pressed, diode just allows electric current you go; Conversely, when polarity contrary (call “ to slant reversely again buy ” ) perhaps be less than to bias voltage guide electrify is pressed, below these two kinds of circumstances, diode won’t allow electric current to pass.

 

From go up at all tell, if you understand PN writtens guarantee, that easy to handle is much, knot of a PN is inside diode.

 

2, the two brother of diode

 

Basis production material is different, diode can be divided for silicon detector and germanium diode

 

(1) silicon detector

 

Guide electrify presses 0.6V~0.7V, need 0.6V at least, medicinal powder heat energy force should compare germanium diode strong;

 

(2) germanium diode

 

Guide electrify presses 0.2V~0.3V, need 0.2V at least, medicinal powder heat energy force is inferior to silicon detector, exceed 85 degrees when calorific temperature, germanium diode cannot use be no longer in force.

 

3, of diode name

 

Normally, in application, we can let the name of diode understand its use with respect to the watch directly. Be like:

 

(1) rectification diode: Undertake rectification to the big electricity that carry or tall voltage; Model is like 1N4001, ~1N4007, 1N5002, 50006, 5008 wait;

 

(2) switch diode: Regard as a switch is used, leave when contented and certain condition, close conversely; Model is like 1N914;

 

(3) demodulation diode: Undertake demodulation to signal; Model is like 1N4148, 1N4445, 1N34A, 1N67A, 1N191;

 

(4) stabilized voltage diode: This kind of diode calls Qi Na diode again, character is till critical and retrorse puncture very tall resistance is had before voltage, go up in puncture dot a resistance is very little, right now although electric current increases, want not to exceed limiting current value only, voltage can keep constant value. So it is to be used reversely, use as of stabilized voltage; Puncture voltage is its stable voltage normally, model if: 1N5225B, 1N4733A, 1N4739A;

 

(5) diode of Xiao Te radical: This diode is very special, it is not general silicon detector or germanium diode, call Xiaoteji’s person the invention by, take this to commemorate him so. By two very main character: It is knot voltage threshold value but low to 0.15V, normally a few bigger it is 0.4V many somes. 2 it is to have extremely small knot electric capacity and rapidder switch rate (10ns) ; So it can detect the signal of low voltage tall frequency that common diode cannot detect. In the meantime, the quantity of heat that produces because of it again is less, the radiator that needs consequently is small also, apply in power source product normally so. Model if: 1N5817581858195822, 1N6263;

 

(6) transfiguration diode: Just as its name implies, transfiguration, its knot capacitance is as the change of retrorse voltage change. The volatile range of transfiguration diode is a few PF normally to 100PF. In be being used at restricting circuit of high-frequency radio frequency normally, the tension that increases with place will change its capacitance, change the frequency of the oscillator thereby. It was used when doing catapult at that time.

 

4, the utility of diode

 

Retrorse polarity protects 4.1 the most commonly used —— :

 

Receive power source instead to prevent, burned-out chip, it is to receive a diode reversely normally, have kind of two kinds of join:

 

(1) series connection join: Diode must carry all load current, use up the voltage of 0.6V, reduced the working hours of the instrument; Want to choose diode according to the voltaic size of circuit so;

 

(2) shunt-wound join: Once be received instead, electric current is met from diode this loop has flowed, won’t shed main circuit. The defect of this method is: Electric current is very big, want to choose to suit the diode of power and electric current so.

 

Series connection diode

 

Shunt-wound diode

 

4.2 The most dangerous utility —— controls transient state

 

According to law arris second law is knowable, should flow to be closed suddenly via the electric current of an inductance bring up the rear, the magnetic field that disappears suddenly can produce the pulse of a very tall voltage on inductance coil, voltage amplitude is as high as hundreds of bend over very consummate kilovolt, if do not try the word of dredge, inductance is in loop to will be harmed very easily. If be in paralell connection of a diode right now inductance two side, so diode offerred short circuit channel for high-pressured pulse, protected the circuit of photograph adjacent thereby. Use on switch power source, relay and electromotor commonly. Following plan institute show:

 

 

The rectification diode that chooses enough power capacity normally or diode of Xiao Te radical. As above graph is diode of Xiao Te radical.

 

Price of diode of Xiao Te radical is some more expensive, but reaction fluid is some faster. No matter why is the attention planted diode, must estimate the voltage of tall pulse adequately, what choose diode to be able to make do to come. This lives or compare danger.

 

4.3 the most amused utility —— undertake Qian

 

Because diode has guide electrify is pressed, the word that is silicon detector commonly is 0.6V, so, can increase a retrorse diode to be in at the same time of signal weaveform to and negative undertake Qian up, citing is as follows:

 

 

Once the amplitude that inputs signal is taller than VCC 0.2 or the word of 0.6V above, source of positive electricity of can immediate flow direction is carried; Once compare the word of VEE small 0.2V or 0.6V above, can immediate flow direction loses power source to carry, protected the input end that carry puts thereby. Other circuit is similar and such principle.

 

4.4 The most extensive utility —— commutate

 

Rectification is sufficient low the one-way conductivity that used diode. Lose half weeks undeely to be communication signal changeover through block pulsatile dc signal. It is with capacitance a combination is used normally, diode series connection, capacitance paralell connection, the action of capacitance is through filling discharge makes output pulse more flowing, more approach dc, it is capacitance of the wave that it is filter. According to need, cent is half commutate and complete wave commutate. The citing of half commutate is below:

 

 

4.5 The utility —— that cannot think of most times pressure

 

In contacted Qian after utility, diode most the place that lets me want to be less than is, it is times OKer to be used jointly with capacitance press.

 

Need two capacitance and two diode only, output end can get inputting the voltage of the double amplitude of signal. Citing is like next graphs:

 

 

Of course, premise is an input signal is communication signal. Half weeks are lost in what input signal, d1 guides, charge to C1 to Vin of peak value voltage, be in next next half weeks, d2 guides, charge to C2, as a result of before C1 has been filled to Vin voltage, so the voltage on C2 is the Vin of peak value voltage of transformer A edge to increase the total of the voltage that C1 stores, it is 2Vin. Half weeks are lost in the next, d2 does not guide, c2 will discharge to load. Got the input tension of 2 times so. It is to be times pressure.

 

 

4.6 the most barpque utility —— stabilized voltage

 

I feel stabilized voltage diode is very strange at the beginning, because it is to turning over those who use, losing reverse to use, unexpectedly won’t burn-up, wait to see a book knew to feel relieved after its working principle later. It is not easy also. Principle already above had told, so not give uncecessary details.

 

5, ending

 

Good, regression most initial problem, the diode action on the side of the inductance in switch power source very clear and clear ——Control transient state, protective inductance is in loop. Because the response rate of diode of Xiao Te radical is rapidder,the account that chooses diode of Xiao Te radical is, and its guide electrify is pressed lower.