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lm339 and pull-up resistor

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Member level 1
Dec 31, 2011
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My lm339 D simulation is showing a leakage current of 2.81mA in the internal collector off state, and an IOL of 400 mA in case of low output voltage whereas on lm339 datasheet it is written the leakage current in output high state to be 0.1nA and IOL to be 6-16mA?

WHy is the simulation faulty?
can a transistor sink more current than its rated value?, if a lesser value pull-upp resistor is used?
Do the value of pull up resistor anything to do with transistor off-state leakage current?

I feel that the output transistor is damaged.
If you have put a less value of pull up resistor, then at output low, the transistor will take more current. Depending on the value of the resistor, this can be any amount. You should select the resistor value that would keep this current below the rated value.

You can calculate this by R = (VDD - VOLmin) / Current.
Select Lower current to prevent damage. Higher current would give better speed but can also cause damage due to heating.

I feel that the output transistor is damaged.
I've understood Khashia is just simulating the circuit and not referring to a real one. Is it so ?
Please post the schematic of your circuit

Oh yeah, its a simulation. I realize that this is why there is still an output and only the current looks weird.
I was wondering how the circuit was still working since at IOL = 400mA, the output transistor would be up in flames!!

@ Khashia, put up the schematic for more details.

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