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| Control JFET using MCU |
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| Kleinstein:
The BSS139 or NSVJ3910SB3 look both OK. There is no explicit spec for R_on, but a curve for I vs V_DS that suggests some 10-20 Ohms as a typical value. It would still need a negative control or supply, e.g. through the charge pump circuit shown by Zero999. |
| gaminn:
OK, I think I will implement BSS139 and the charge pump circuit mentioned above. |
| Zero999:
The NSVJ3910SB3 has an on resistance of 30R or better, when ID <10mA, but the BSS139 is cheaper and has a lower on resistance, so go with that. --- Quote from: janoc on August 20, 2019, 10:17:25 am --- --- Quote from: gaminn on August 20, 2019, 08:53:05 am ---When there is no power I want the switch to be ON. That is why I want to use JFET. --- End quote --- That sounds like you want a depletion-mode MOSFET and not JFET --- End quote --- It just needs to be a depletion mode device, be it a MOSFET or JFET. |
| janoc:
--- Quote from: Zero999 on August 20, 2019, 12:56:26 pm ---It just needs to be a depletion mode device, be it a MOSFET or JFET. --- End quote --- Given that it is for a switching application, the MOSFET is likely a more logical choice. |
| Zero999:
--- Quote from: janoc on August 20, 2019, 06:44:09 pm --- --- Quote from: Zero999 on August 20, 2019, 12:56:26 pm ---It just needs to be a depletion mode device, be it a MOSFET or JFET. --- End quote --- Given that it is for a switching application, the MOSFET is likely a more logical choice. --- End quote --- Why? |
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