J113 JFET replacement for constant current source

ra7

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For <20 mA, the DN25 series is not recommended because of high capacitance. What is the problem with using J113 in the ACP+? If you get a value different than 10 mA, simply adjust R4. Higher values give lower current.
 
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Are you sure that J113 is good choice for 10mA CCS?
Idss (minimum) is 2mA at 15V Vgs.

I would rather use instead of it higher Idss device, as J111 or J310 in cascode cCCS (with any IXTP) as EUVL suggested.
 
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For <20 mA, the DN25 series is not recommended because of high capacitance. What is the problem with using J113 in the ACP+? If you get a value different than 10 mA, simply adjust R4. Higher values give lower current.
There is no problem for J113. Just asking for any options for any updated FET chip in the industry. Meanwhile I will anticipate the order of possible resistors (for 1 time order) needed to target 10mA thru R4. Thank you for your inputs.
 
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ra7

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I wouldn’t worry about the so-called “intended” use. If that were the case, we would’ve run out of parts a long time ago. If the curves are applicable and the other specs are right, why not use it? It is very convenient to use J113.
 
Well, yeah, but since it's a short channel device, the current may vary more with Vin - this was my experience with its brother device from the NCB grouping, the PN4393, when I tried to use it as a current source in earlier efforts. Since the J113 is the lowest in the IDSS ranking of the J111-J113 series, it might fare better in that respect. It's certainly one of the last jfets you can buy these days that has leads.....
 
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