Programmable from 1µA to 10mA. □ ±3% initial accuracy. Description. The LM/LM/LM are 3-terminal adjustable current sources characterized by . LMM Texas Instruments Current & Power Monitors & Regulators NRND, alternate is LMM/NOPB datasheet, inventory, & pricing. LMM/NOPB Texas Instruments Current & Power Monitors & Regulators 3- TERM ADJ CURRENT SOURCE datasheet, inventory, & pricing.

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Note as well that the actual circuit ground is on the top side of R1 – Vout is the ground potential for the purpose of this circuit. Any real current source will have a voltage limit beyond which it will not deliver a constant current.

National Semiconductor

From there, it’s just a matter of tuning either the set resistor of the LM or daatasheet voltage threshold to trim to the setpoint. In the schematic, I1 represents the LM My goal is to make an alarm of sorts when that impedance exceeds a threshold, and the way I want to do that is to detect when the is in current limiting mode. The trip point is intended to be no higher than ohms per volt – 10k. In the case of the LM, it is rated with a voltage drop of 2.

Datasheet «LM334»

Nov 13 ’15 at When the 1 mA of current is reached, it should begin to increase its resistance, thus increasing the voltage drop dztasheet it. Kuba Ober 1, 10 I’d like to measure the voltage drop and light an LED really an optoisolator when it exceeds a threshold. If anyone else has an idea of how to light an LED when an LM is actually limiting the current through it, that would work too. Post Your Answer Discard By dtasheet “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.


LMM datasheet, Pinout ,application circuits 3-Terminal Adjustable Current Source

If the voltage is more than 2. Post as a guest Name. How to tell when an LM is limiting the current?

All of that is true. The load has a variable impedance. You can increase the resistance of the divider if you can use a larger load resistor R3 or a higher-gain transistor. R2 completely determines the behavior of datasbeet system, when looked at from outside, and sets the leakage current.

Usually when a current supplied less than the current required, there is a voltage drop. Nope, it won’t work.

When it’s passing less than 1 mA of current, I would expect it to be acting like a very low-value resistor, meaning that the voltage drop across it should be low. Furthermore, I think it’s rather crazy that you allow such high ground impedance 10k.

The question at hand is how best to detect when the voltage across the LM exceeds datashset threshold. Sign up or log in Sign up using Google. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The intent now is to connect the output to ground and measure the voltage drop across it instead.


The LM in this case does not have an infinite voltage with which to overcome the load impedance.

It’s also intended to at least attempt to desensitize the circuit to the tolerance variation of the k resistor and the supply voltage. The divider produces about 0. The typical performance is shown in the datasheet in this graph: Spehro Pefhany k 4 In the old circuit, the output drives an optoisolator’s LED, but that circuit isn’t accurate or sensitive enough.

Sign up using Email and Password. Please edit your question and delete the comment. If the load impedance is high, then the current will be much lower than the limit. The current darasheet is ,m334m to limit the amount of ground leakage. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. The comparator could be something like half an LM