• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 48 subscribers
  • Views 2802 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ideal diode with OPAMP + Pch MOSFET

K.Yaita
Guru 29690 points
Other Parts Discussed in Thread: OPA191, OPA197, TINA-TI

Hi Team,

My customer considers to design an ideal diode with OPAMP + Pch MOSFET as the following.
http://www.edn.com/design/analog/4368525/Use-a-self-powered-op-amp-to-create-a-low-leakage-rectifier

I would like to suggest TI OPAMPs, is there any application note for this requirement?
My customer's requirement is the following and I believe OPA197 and OPA191 is applicable.
---------------------------------------
1) Vin=4～25V
2) reverse leakage current: less than 1mA
3) maximum reverse voltage: more than 28V
4) on resistance: less than 30mΩ
 *I think 2) and 4) are requirements for Pch MOSFET.
---------------------------------------
May I have your comments?

Best Regards,
Yaita / Japan disty

  • 0
    TI__Guru 62625 points
    Hello Kensuke,

    Can you confirm your #2 requirement was for a reverse leakage current < 1mA and not a smaller level? Less than 1mA of reverse leakage current could be easily achieved with a standard diode.
  • 0 in reply to Collin Wells
    Guru 29690 points

    Hi Collin-san,

    Yes, reverse leakage current that my customer requires is less than 1mA.
    it is better if it can be lesser of course.

    My customer wants less forward drop than a diode, so he considers to this solution.
    Your support would be really appreciated.

    Best regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru 62625 points

    Hello Yaita-san,

    This solution can be used to achieve forward drops much lower than a standard diode, while still providing the desired rectification function.  The requirements for the op amp in the customer's application are as follows:

    1.)  Supply voltage range from +4V - +25V.

    2.)  An input common-mode voltage that includes V+

    3.)  An input stage that does not include back-to-back diodes (see TIPL videos)

    4.) A quiescent current < 0.5mA

    The OPA191 is the only product available that meets the requirements for this application.  There are a few other devices that are rail-to-rail, cover the supply range, but they are bipolar devices that include back-to-back input diodes which prevents them from working with this circuit.

    The OPA191 has an input supply voltage range from +4.5V - +36V.  Which is slightly above the desired +4V minimum supply voltage.

    I've attached simulation files with results for this circuit using the OPA191:

    6153.Original.TSC

    Open-Loop.TSC

  • 0 in reply to Collin Wells
    Guru 29690 points

    Hi Collin-san,

    I appreciate for your great support.
    I also confirmed your result by using TINA-TI and will support my customer continuously.

    Best Regards,
    Yaita