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LMN Datasheet: LMN / DIP 8 Pin / Low Voltage Audio Power Amplifier, LMN PDF Download FCISemiconductor, LMN Datasheet PDF, Pinouts. These are the first monolithic JFET input operational ampli- fiers to incorporate well matched, high voltage JFETs on the same chip with standard bipolar. LFN/NOPB Texas Instruments Operational Amplifiers – Op Amps JFET INPUT OP AMP datasheet, inventory, & pricing.

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Dec 27, 1. Sep 20, I am trying to setup a constant current source using a 2n lj356n a Motorolla LMN. I want to ensure 4mA collector current regardless of my load. Here is a screen shot of the circuit, an explanation of my rationale, and the problem I am having.

My Rationale Using lm356m datasheet, to the best of my ability, it looks like my DC current gain would be By that logic my base current, 3. The LMN does not go rail-to-rail so the output is 3.

2n3904 DC current gain confusion

Datasheft the voltage across my sense resistor exceeds 4V, 4mA total current, the LMN will output low unbiasing the 2n I know I may have to implement some hysteresis into this circuit. I am pretty sure I’m interrupting the datasheet incorrectly. Could someone explain this section to me? How I see it if I’m fully on, what would my collector current be? With that information I assumed I would reference the 3rd entry for the behavior I could expect. Also, Vce is listed as 1V here.


LMN Datasheet, PDF – Alldatasheet

How does this factor in? As it stands right now, I get 2. What exactly am I screwing up here? Lastly, I’ve heard it is poor practice to use an op-amp as a comparator without some sort of hysteresis.

How can I implement this here? Thank you all so much for any input. Hopefully, I was clear in my explanation. Dec 27, 2. Mar 30, 7, 1, An easier to read schematic: You have several problems. The output voltage is only guaranteed to be 3. To avoid these issues, you can change your voltage divider to use a voltage below the guaranteed max input voltage.

That will also help with the max output voltage. You can omit the base resistor. Your beta assumptions are wrong. Beta is also dependent on Vce.

You only need 4mA, so beta isn’t a critical parameter.

Use a ohm resistor for Rsense and set the voltage divider to give you 0. Dec 27, 3. Jun 29, 8. If you have 3. The second key to this circuit is that the transistor emitter current equals to the collector current.

Hope this helped, Kevin. Dec 28, 4. Mar 4, 2, Dec 28, 5. Dec 28, 6. Dec 28, 7. Aug 1, 7, 2, You didn’t show the entire datasheet page, but I think the DC gain of 70 is a minimum value for that collector current.

It should not be used a design parameter for several reasons. Most importantly, the opamp gain at DC is around , so that additional 70 doesn’t really figure into the gain equations. The opamp and its negative feedback will automatically adjust Q1 base current such that the voltage across sense resistor R5 is identical to the voltage across R4.


Delete R1 for now.

Its purpose is to protect Q1 from too much dafasheet current, which is not a problem in this circuit. Depending on the value of the sense datsheet there is a chance that the opamp output might not be able to swing low enough to drive Q1 correctly.

In this case, something in the 1K to 10K range might help, but I wouldn’t put it in until needed. Dec 28, 8. Dec 28, 9.

Dec 28, Dec 29, Mar 14, 20, 5, I’d like to make a few comments: Dec 20, 10, 1, Why does your schematic drawing software produce backwards negative white lines on a black background instead of a normal positive image?? Also can’t you turn off the “chicken pox” dots?? Dc gain Posted by Yuvaloh1 in forum: DC current gain Posted by qitara in forum: AC gain confusion Posted by vustudent in forum: You May Also Like: Both datashet connections and USB to serial conversion connections are covered.

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