Zener diode parameter explanation

小太阳yy

Zener diode parameter explanation [Copy link]

 

Does the parameter of this Zener diode mean that when it breaks down in reverse, the voltage is stable between 5.6V and 5.71V? Why is the actual value I measured about 1V smaller?

chunyang

First confirm whether your test circuit and test instrument are normal, and then check whether the test device corresponds to the device in the table. If both are true, you can only say that you bought a fake, but if you seriously doubt this, you may suspect that there is something wrong with your test circuit or test conditions, because it is very rare to encounter fake Zener tubes, or you are testing a faulty part after disassembly of the board?

maychang

"Does the parameter of this Zener diode mean that when it breaks down in reverse, the voltage is stable between 5.6V and 5.71V?"

no.

It means that under the specified test conditions, the typical value of the stable voltage is 5.6V, the minimum is 5.49V, and the maximum is 5.71V. If it is less than the minimum value or greater than the maximum value, it is unqualified.

maychang

"Why is the value I actually measured about 1V smaller?"

How did you measure it?

小太阳yy

maychang posted on 2022-6-8 15:53 "Why is the actual value I measured about 1V smaller? 】 How did you measure it?

According to the circuit above, I used a voltmeter to measure the voltage and it is indeed 4.6V. This is the problem. . .

小太阳yy

chunyang posted on 2022-6-8 15:52 First confirm whether your test circuit and test instrument are normal, and then check whether the test device and the device in the table actually correspond. If they are, you can only say that you bought...

tangdianzi

maychang posted on 2022-6-8 15:53 "Why is the actual value I measured about 1V smaller? 】 How did you measure it?

Don't worry about so many problems. Find a normal pipe to test first to see if there is a problem with the instrument. Try again after eliminating the problem with the instrument.

tangdianzi

Xiao Taiyangyy published on 2022-6-9 08:20

There is something wrong with this tube. It is not within the normal range.

maychang

小太阳yy posted on 2022-6-9 08:19 According to the circuit above, I used a voltmeter to measure the voltage and it was indeed 4.6V. This is our problem. . .

In the picture you posted in your first post, it is clearly marked [V Z @I ZT ], and the column behind it clearly marks I ZT as 5mA.

Is the current through the Zener diode 5mA when you test it?

maychang

Xiao Taiyangyy published on 2022-6-9 08:20

In addition, there is a diode D in the figure. Why is this diode placed here? It is useless and superfluous.

maychang

Xiao Taiyangyy published on 2022-6-9 08:20

In addition to the current through the Zener diode, you also need to determine whether your multimeter is accurate. You should calibrate your multimeter.

maychang

tangdianzi posted on 2022-6-9 08:23 Don't worry about so many problems first. Find a normal pipe to test it to see if there is a problem with the instrument. After eliminating the problem with the instrument, try again...

"Don't worry about so many problems for now. Find a normal pipe to test and see if there is a problem with the equipment."

Can you let me find a normal pipe to test it?

luck_gfb

Vz@Izt depends on the voltage range. When the current flowing through the Zener diode is Izt (5mA), the voltage value of the Zener diode can be within the range of the specification.

chunyang

Xiao Taiyangyy published on 2022-6-9 08:20

Pay attention to the test conditions. As mentioned in the premise, you may have a problem with your test conditions. In your test circuit, remove D and choose a suitable R value so that the current through the Zener is about 5mA as specified in the manual.

小太阳yy

maychang posted on 2022-6-9 10:02 In the picture you posted in the first post, it is clearly marked [VZ@IZT], and the column behind it clearly marks IZT as 5mA. The current passing through the voltage regulator tube when you tested it was...

Maybe it’s 6mA...

小太阳yy

chunyang posted on 2022-6-9 13:27 Pay attention to the test conditions. As mentioned in the premise, I suspect that there is something wrong with your test conditions. In your test circuit, remove D, select a suitable R value, and pass the Zener...

If a diode is used, can the circuit also be made 5mA? Find the voltage value of 5mA corresponding to the diode, then subtract the voltage across the diode from the front voltage, then subtract the voltage across the Zener diode, and then divide the resistance value to get the current 5mA. Choose the appropriate resistor. I understand correctly, teacher.

小太阳yy

maychang posted on 2022-6-9 10:04 In addition, there is a diode D in the picture. Why is this diode placed here? It is useless and superfluous.

It is like this, teacher. My drawing is not complete. The 10V voltage is output by two DC-DC chips. The output chips of the two DCDCs are both 10V. Then a diode with a common cathode and two anode pins is added here. My understanding is to isolate the two voltages to avoid random voltage feedback. Is my understanding correct? Please correct me.

小太阳yy

maychang posted on 2022-6-9 10:06 "Don't worry about so many problems first, find a normal tube to test and see if there is a problem with the instrument." Let me find a normal tube to test...

He is talking about me, teacher, I must be the one to take the test

小太阳yy

chunyang posted on 2022-6-9 13:27 Pay attention to the test conditions. As mentioned in the premise, I suspect that there is something wrong with your test conditions. In your test circuit, remove D, select a suitable R value, and pass the Zener...

You are right, teacher.

maychang

小太阳yy posted on 2022-6-9 21:15 If a diode is used, can the circuit also be made 5mA? Find the voltage value of 5mA corresponding to the diode, and then subtract the voltage across the diode from the front voltage...

Why bother? The test only requires 5mA of current, and any DC-DC chip has this output capability.

Use a DC-DC power supply of 10V, remove the diode, and use an 880 ohm resistor to make the current in the voltage regulator tube 5mA, provided that your 10V voltage is accurate.