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FET for CCLD, Constant Current Line Drive (sensors)

Yoshikazu Kawasaki
Intellectual 851 points
Other Parts Discussed in Thread: CSD18541F5, CSD17483F4

Hello,

My customer is searching for a FET which can be used for CCLD(Constant Current Line Drive).  It seems it is also called as IEPE, ICP, Delta Tron and so on depending on the equipment makers because there were several names before IEEE standard is established, but would you please tell me if there is?

Best Regards,

Yoshikazu Kawasaki

  • 0
    TI__Mastermind 38040 points

    Hello Kawasaki san,

    Thanks for promoting TI FETs at your customer. What are the voltage and current requirements for the FET? From what I have read, the current is small (4mA) and the supply voltage is typically in the 24V to 30V range. This is probably an application for a small signal FET in the 30V to 60V range. TI does not make small signal FETs as our devices are higher performance. In 30V, I'd recommend the CSD17483F4 FemtoFET. In 60V, the CSD18541F5 FemtoFET would be my recommendation.Take a look and let me know what you think.

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    Intellectual 851 points

    Hello John-san,

    Thank you very much for your quick reply.  Yes, as you mentioned the expected voltage is up to 30V and the current is up to 4mA.  The ICs you suggested may work well, but do you know if there is a customer who has used on such application?

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Mastermind 38040 points

    Hi Kawasaki-san,

    I am not aware of customers using these devices in this particular application. These FemtoFETs go into all sorts of applications including industrial, personal electronics, communications and enterprise. Both FETs I recommended include gate ESD protection as well.

    Best Regards,

    John

  • 0 in reply to John Wallace1
    Intellectual 851 points

    Hello John-san,

    I got additional information from the customer.  They use LSK170A of Linear Systems which isn't MOSFET, but JFET.  They'd like to lower the leakage current at high temperature with similar function.  Do you have a proposal for this?

    Best Regards,

    Yoshikazu Kawasaki

  • +1 in reply to Yoshikazu Kawasaki
    TI__Mastermind 38040 points

    Hi Kawasaki-san,

    Thanks again for promoting TI FETs to you customer. I reviewed the JFET datasheet and it looks like its leakage is much lower than the leakage for our MOSFETs. For example, the CSD17483F4 specs a maximum gate-source leakage, IGSS < 50nA at VGS = 10V. The CSD18541F5 is even higher. The leakage also increases with temperature. Please visit our MOSFET Support & training page where you will find a technical articles on gate ESD structures and howhow leakage varies with temperature.

    Best Regards,

    John

  • 0 in reply to John Wallace1
    Intellectual 851 points

    Hello John-san,

    Thank you very much for supporting me.  The JFET for this application is quite special, so I understand there is no IC you can propose to meet the customer's requirement, lower leakage current than LSK170A.

    Best Regards,

    Yoshikazu Kawasaki