Electronics > Projects, Designs, and Technical Stuff
Mosfet with Low Idss ?
namster:
i need to reverse a precision current with Symetrical value , to cancel thermoelectric EMF , so I tried to use a H bridge but this did not give the expected result a leakage current has alteared the Reference Current ! , i think that was caused by Idss Current of Mosfet the IRFz44 has a Idss of 40µA wich mosfet can i use ? or there is another solution ?
note : i have simulate the Idss with a 1k Resistor !
T3sl4co1l:
Why 1k resistors in parallel? Tried without?
Why IRFZ46? That's a fuckoff huge transistor for switching a 1mA current. Why not 2N7002, say?
Tim
namster:
i add this 1k resistor because the simulator don't take Idss in consideration , there is another technique to simulate it ?
i used a IRFZ46 because That's what I had available , 2n7002 is a good choise but i have 4 Range of Current ( 1 mA 10mA 100mA and 1A) the absolute Maximum current of 2n7002 is 200 mA .
T3sl4co1l:
Oh, then just go with like Si2304BDS. Something smaller. I suppose even IRF510 would be something.
You aren't likely to find a part that guarantees low leakage, especially not at high currents, but typical leakage is much better than the worst case figure. The reason is it takes time to measure low currents, and time is money.
Tim
exmadscientist:
--- Quote from: T3sl4co1l on August 25, 2019, 11:43:30 pm ---You aren't likely to find a part that guarantees low leakage, especially not at high currents, but typical leakage is much better than the worst case figure. The reason is it takes time to measure low currents, and time is money.
--- End quote ---
For what it's worth, Philips NXP Nexperia has a series of "low-leakage" FETs. The specs aren't particularly impressive (25 nA guaranteed) but, hey, that's something. I seem to recall another manufacturer also has such a line but at the moment I can't remember which one.
Nexperia's catalog lists these parts as PMZ600UNEL / PMZB600UNEL (N-Ch), PMZ950UPEL / PMZB950UPEL (P-Ch), PMDXB600UNEL (Dual N-Ch), PMDXB950UPEL (Dual P-Ch), and PMCXB900UEL (dual complementary).
Oh, and they're in one of those satanic tiny little 1mm by 0.6mm DFN packages. Just in case you need an excuse to buy a JBC Nano station....
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