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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I need to use an opto between this circuit and the logic systems for safety. It’s not possible to give a good answer without much more information such as a complete schematic and accuracy requirements. The detection threshold would be something like 1V. Othewise, the load is getting the maximum voltage that the source can provide, and is not running at full current. Datasheeg 25C, the LM has a minimal drop-out voltage of about 0.
So what you do is connect R2 directly between L and PE terminals.
3-Terminal Adjustable Current Source
R2 completely determines the behavior of the system, when looked lm334j from outside, and sets the leakage current. 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 intent now is to connect the output to ground and measure the voltage drop across it instead. At least, that’s my thinking at the present. Post as a guest Name. Note as datashet that the actual circuit ground is on the top side of R1 – Vout is the ground potential for the purpose of this circuit. The reference could be derived from a regulated supply voltage ml334m as 5V with a voltage divider.

You need a different design, and I question the need for a current source. This will vary over temperature and from unit to unit, that’s what they mean by ‘typical’.
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 circuit in this case is a Ground Continuity Monitor.
The typical performance is shown in the datasheet in this graph:. 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. How to tell when an LM is limiting the current?
Any real current source will have a voltage limit beyond which it will not deliver a constant current. By clicking “Post Your Answer”, you acknowledge that you have read datasgeet updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Sign up using Email and Password. If the load impedance is low, then the current will hit the limit.
I have an LM based constant current source configured to supply a max of 1 mA. I’d like to measure the voltage drop and light an LED really an optoisolator when it exceeds a threshold. R1 represents the ground impedance – the goal is to detect when it’s value exceeds 10k.
LMM Datasheet(PDF) – National Semiconductor (TI)
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The actual earth is on the far side of R1. If that current doesn’t flow, then that’s an error. I don’t see a way in circuitlab to represent an actual LM, so the simulation likely won’t operate correctly.
A couple of resistors and a comparator with built-in reference l3m34m do the job in a much simpler fashion. The current limiter is intended to limit the amount of ground leakage. Tyler Think of it rather as a current limiter. When the 1 mA of current is reached, it should begin to increase its resistance, thus increasing the voltage drop across it. The question at hand is how best to detect when the voltage across the LM exceeds a threshold.
