Will a buck converter cause too much noise in a signal termination circuit?

Support Voltage regulators
1

I am looking for ways to update an old circuit which used an op-amp to regulate voltage to 2.7V. This is part of an active termination circuit used for vintage S-100 bus computers. An example of this circuit can be seen here: S100 Computers

I was hoping that it could be as simple as using an adjustable regulator like the D36V6ALV (Pololu - 2.5-7.5V Adjustable Step-down Voltage Regulator D36V6ALV) or maybe the fixed 2.5V regulator like the D24V5F2 (Pololu 2.5V, 500mA Step-Down Voltage Regulator D24V5F2).

However, others have stated concerns regarding the amount of high frequency noise produced by Pololu’s switching regulators. Introducing that noise into the termination network for all the S100 bus signals would be a problem.

I was wondering if I could get an engineer’s thoughts on this matter? Would something like the D36V6ALV introduce noise on these signal lines? Is there anything that could be done to reduce/filter this noise?

2

Hi

Switching regulators do produce some noise which will have some effect on your circuit. Seeing 100mV pk-pk or more on the output of those regulators under some conditions would not be surprising. Whether that is enough to disturb your S100 computer, I do not know; you would probably need to test it yourself. You could add a low pass filter on the regulator output or use a linear regulator instead.

If you do decide to try one of our regulators, I expect the D36V6x family to be less noisy than the D24V5Fx family. If so, we would be very interested to hear about your testing!

-Claire