LM4250 Programmable Op Amp Replacement

The form would not let me enter LM4250 as a part number.

Please help me find the closest replacement for the obsolete LM4250 Programmable Operational Amplifier.  There may be other ways to solve this with analog switches, but I am going for the direct approach first.  This is how we have used it for many years:

I’ve been thinking about this more.

Since we are using this LM4250 programmable Op Amp in only one of two states, it is essentially a digital control, either 1.) ON and operating as a normal unity gain Op Amp buffer, or 2.) OFF where the Op Amp is in a very low power mode with the output in a high impedance state.  BUT … the input still has to function in a very high impedance mode so as not to load down the CA3080 OTA that is feeding it.

The CA3080 (in the sketch I provided) has a high impedance output and can NOT drive the XR2211 directly.  The XR2211 has an input resistance of 20 KOhms when powered up.  Therefore we needed to buffer the CA3080 with a unity gain buffer.  But also, we power down the XR2211 to save power in between FSK communications, and if I am remembering correctly, the XR2211 input resistance of 20 KOhms becomes much lower during power down.  So we needed a way to basically “tri-state” the Op Amp buffer so that it can’t source any (wasted) current when the XR2211 if powered down (that also could short circuit the Op Amp output).  Confusing, I know.  So maybe I don't need a programmable Op Amp.  Maybe an Op Amp with Shutdown will work.

I have been looking at your TLV9001S with Shutdown.  Can it do everything I need ?  Its datasheet states that its output is high impedance in shutdown.  What about its input ?  Can it function with the two 1.4M resistors on its input as shown in the sketch ?

Based on your Application Note SBOA367B, Designing for TLV90xxS Operational Amplifiers With Shutdown … … …

From Section 6.2 of SBOA367B:  “Most of the time, non-inverting circuits can be used with minimal worry about signals coupling through to the output.  However, it is still a good idea to verify the frequency response of the circuit at any frequencies of interest and ensure no downstream issues will arise.”

Does this circuit appear to meet my constraints ?

Since we are at a fairly low frequency of 30 kHz, it would appear that this circuit will not load down the previous stage of the CA3080 OTA in normal operation or in shutdown.

And when in shutdown could a short circuit to ground be applied to the output of the TLV9001S with no issues at all ?

Thanks very much for your help !