Post Go back to editing

ADA4522 feedback resistor

  • I built a low pass filter with ADA4522

  • Officially recommended filter circuit with no feedback resistance

  • However, the ADA4522 manual recommends increasing the feedback resistance

  • In this application, do we need to increase the feedback resistance?

  • thanks
Parents
  • Hi seekyong,

    I think you're referring to ADA4522 datasheet Figure 75 where a finite feedback resistor (instead of a direct short) is used for a buffer configuration.

    I don't think you'd need to worry about excess input current flow (due to the input clamp circuit turning on). With LTspice simulation, the maximum diff input signal is limited to +/-3.5mVp which is not enough to turn on the clamps. The signal that reaches the non-inverting input is sufficiently slowed down by R4, and C4 in your schematic (this is my rationale, but I could be wrong):

    Here is the simulation file if you'd like to experiment with it in LTspice:

    ADA4522 LPF EZ 4_19_20.asc

    Regards,

    Hooman

Reply
  • Hi seekyong,

    I think you're referring to ADA4522 datasheet Figure 75 where a finite feedback resistor (instead of a direct short) is used for a buffer configuration.

    I don't think you'd need to worry about excess input current flow (due to the input clamp circuit turning on). With LTspice simulation, the maximum diff input signal is limited to +/-3.5mVp which is not enough to turn on the clamps. The signal that reaches the non-inverting input is sufficiently slowed down by R4, and C4 in your schematic (this is my rationale, but I could be wrong):

    Here is the simulation file if you'd like to experiment with it in LTspice:

    ADA4522 LPF EZ 4_19_20.asc

    Regards,

    Hooman

Children
No Data