Working out the current limiting resistor we have: The ones with voltage of 5. As I pointed out in my query, I used the test currents from the relevant datasheets as a guide. Kvegaoro 2, 11 No load except for the DMM. How much current will th load require? The problem is how you are modeling your circuit, because the series resistance you are using is so close the zener resistance, it must included in the circuit model.

Author:Marr Goltisho
Language:English (Spanish)
Published (Last):10 September 2009
PDF File Size:14.65 Mb
ePub File Size:2.84 Mb
Price:Free* [*Free Regsitration Required]

Gonos Typically the dynamic resistance of the 1NA is about 5 ohms, so you could approximate it with an ideal 3. Sign up or log in Sign up using Google. Zeners are notoriously power inefficient even at no load. Buck8pe 8 Post as a guest Name. Actually, it was a candidate for a regulated supply fed by a CCS.

Even if it specified at 70mA, there is going to be some there and in this case it is not negligible therefore it must be incorporated in to your circuit model, that why your circuit analysis provides a different answer but adding the zener resistance to the model gives a solution that dataxheet more closely your result. No load except for the DMM.

How much current will th load require? By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. What output volta de you require? See Fig 2 in diodes. The ones with voltage of 5. If you include the dynamic resistance in the model, you must use a lower voltage for the ideal zener.

Does this conflict with what Kvegaoro is saying? Try to find a datasheet for your specific zeners which shows the breakdown characteristics. The dynamic resistance of the Zener may not be able to drop low enough, even with 70mA available to it, to make the proper resistor datassheet equivalent for the satasheet to be equal to 3.

Null 4, 10 22 I have a question about the regulation accuracy or lack of of a 3V6 Zener diode. Spehro Pefhany k 4 The closer to the minimum input voltage the more difficult it will be to avoid large changes in current flowing through the TL There are a couple of issues here.

The next problem is that at 70mA and 4 volts, the power is 0. Can you expand on the statement: I suppose the point is, at 70mA, according to the datasheet, the voltage across the zener should be 3.

Sign up datassheet Email and Password. As shown in the circuit below which models the behavior that you are seeing of a voltage reading of about 4V from the zener diode simulate this circuit — Schematic created using CircuitLab. The two Zeners in question are: Kvegaoro 2, 11 Indeed it would seem to be a much easier solution to just get an adjustable LDO, if 1na thing is meant to be used as regulated supply voltage.

As I pointed out in my query, I used a test currents from the relevant datasheets as a guide. Home Questions Tags Users Unanswered. I set up the standard test circuit shown below. You may be on right but it sure makes working out datasheey correct resistor value a chore. Therefore a better model of the zener diode is the zener diode plus the zener resistance in series. If you increase the resistor the voltage across the zener should go down. First this stated in the question: Related Posts


ON Semiconductor 1N4729A





Related Articles