The LM LM series are monolithic frequency to voltage converters with a high gain op amp comparator de- signed to operate a relay lamp or other load. uses a charge pump technique and offers frequency doubling for low ripple, full input protection in two versions (LM,. LM) and its. The LM, LM series are monolithic frequency to voltage converters with a high gain op Details, datasheet, quote on part number: LM

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How are you pulsing the 14V? I want to learn working principle and internal circuit of the IC, and function of externally connected components especially C I’m guessing the AC input lm29917 required to be centered on 0V, incidentally, but a DC blocking cap outside the chip would easily achieve that.

National Semiconductor – datasheet pdf

Sign up using Email and Password. How do I choose value of C41 I put a random one for now? Page 1 of the data sheet says it all.

I would take pin 1 and bias it with two 20K or so resistors going to supply and ground. Andy aka k 10 Here’s a hand-waving explanation from a digital and software guy who has bumped in to sharp edges in the analog side I’ve substantially edited this text to make it more true, see the edit history to see my incorrect babbling if you really want to.


National Semiconductor

Then put a 10K resistor to the cathode of D3 and the other end of lm291 to ground. RBerteig 6 Checkout my projects development blog SLiDA.

I’ve played around with a few variations. Home Questions Tags Users Unanswered. I feel well past my depth trying to sort this out Pin 11 and Pin 1 are the two inputs of a voltage comparator.

The second op-amp is buffering the signal stored on C41 and driving the output transistor, it has feedback from the output to xatasheet -ve input which is a common configuration for a unit-gain buffer.

Then you stand a chance datqsheet getting the input to switch. I guessed the roles of the capacitors completely wrong initially.

I’m trying to make a frequency-to-voltage converter by using LM C41 is a filter capacitor to reduce the ripple from the charge pump. Post as a guest Name. The sig-in line goes from 5.

If I pulse 14V onto the “Signal In” port with that powersupply also connected to ground However you have no DC biasing on Pin 1 so it will just swing about with the AC coupled input and not do anything. All the capacitors and resistors are connected to ground; I’m very confused at this step.


R46 is acting as a load for the charged signal. I’ve built this on a breadboard using a modified version of http: You have fixed Pin 11 at about 0. C40 is being charged by dumping charge into it lm917 each zero crossing or perhaps at one edge only of the Datssheet input. I created a custom library for this IC and set up my own circuit as seen in the schematics above.

But how does this charge pump do this? You want it to keep the measurements stable. 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.