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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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3-Terminal Adjustable Current Source

Usually when a current supplied less than the current required, there is a voltage drop. If the load impedance is low, then the current will hit the limit. Remember that this circuit datqsheet act appropriately during faults – and then the LM is a short. I’d like to measure the voltage drop and light an LED really an optoisolator when it exceeds a threshold. So if you monitor the voltage across the LM perhaps with a comparator you can have a good idea of whether it is working or not.

The intent now is to connect the output to ground and measure the voltage satasheet across it instead. It’s also intended to at least attempt to desensitize the circuit to the tolerance variation of the k resistor and the supply voltage. Datashert 13 ’15 at The LM in this case does not have an infinite voltage with which to overcome the load impedance.

At 25C, the LM has a minimal drop-out voltage of about 0. Post as a guest Name.


Othewise, the load is getting the maximum voltage that the source can provide, and is not running at full current. R1 represents the ground impedance – the goal is ml334m detect when it’s value exceeds 10k.

National Semiconductor

In the case of the LM, it is rated with a voltage drop of 2. The load has a variable impedance. Home Questions Tags Users Unanswered. Tyler Think of it rather as a current limiter. Post Your Answer Discard 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 detection threshold would be something like 1V. 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. Please edit your question and delete the comment.

National Semiconductor – datasheet pdf

The comparator could be something like half an LM All of that is true. A small current from an AC supply is intentionally “leaked” to ground. This will vary over temperature and from unit to unit, that’s what they mean by ‘typical’.

The typical performance is shown in the datasheet in this graph:. The divider produces about 0. When it’s passing less than 1 mA of current, I would expect it to datashete acting like a very low-value resistor, meaning that the voltage drop across it should be low. The circuit in this case is a Ground Continuity Monitor. The trip point is intended to be no higher than ohms per datashset – 10k.


Can R3 be replaced with an opto-isolator diode and series resistor?

LMM Datasheet(PDF) – National Semiconductor (TI)

A satasheet of resistors and a comparator with built-in reference would do the job in a much simpler fashion. Sign up or log in Sign up using Google. If the load impedance is high, then the current will be much lower than the limit. I’d expect it to be minimal, however, since the should be trying to pass as much current as it possibly can.

At least, that’s my thinking at the present. It depends on GREATLY on how the LM is connected high side or low side, for example and how much your current is and how much error you can tolerate any monitor circuit will lower the output impedance. Spehro Pefhany k 4 In the schematic, I1 represents the LM Sign up using Facebook. I need to use an opto between this circuit and the logic systems for safety. In the old circuit, the output drives an optoisolator’s LED, but that circuit isn’t accurate or sensitive enough.

Any real current source will have a voltage limit beyond which it will not deliver a constant current.