How do you calculate the 35mA? If the output is driven to the clamped 12V, the OP will try to sink at most current as it can. Therefore I would assume 12V/100R = 150mA? But the current should be limited by the OP.
I played around with the 100nF output cap, but I don't like the results .
Hello,
my idea was:
the zener clamps to around 15V@50 mA
the 15V go from the zener via the 100R over the OP-Amp internal output ESD protection diode to the +VBAT (10.8V when empty) rail
so we have 15V - (10.8 + 0.7V) = 3.5V difference.
Ok of course I did not regard that the output also will draw some current.
If you have a better idea against EMV it is welcome.
Earlier in this thread I had about 30uV difference between unbuffered (filtered) and buffered (not filtered) reference output before I added the 100 nF.
By the way: it is time to develop a home lab compatible test method for checking the effectiveness of EMI measures.
I have in mind coupling some RF between the reference and the DMM onto the cable via a 100pF - 1nF capacitor.
Perhaps we would also need a decoupling network on the DMM side.
Unfortunately I have only a signal generator up to 20 MHz. I think that some 10kHz to around 300 MHz would be fine.
with best regards
Andreas