How to protect 1.8V ADC and other pins.

Hello all,

How should the 1.8V ADC (and other) pins be protected? One method may be the attached, voltage divider of 1M/100K then limited by two diodes in series. (Not tested, just paper design currently.)

I’d like to explore other methods or suggestions. I have some old or obsolete parts that I can use with info from data sheets. But it’d be nice to go “modern”.

What about VCO to optoisolator? (Think of hostile / automotive applications.)

Suggestions: Circuits, books, URLs?


Fred Kerr

20180830_0902.fzz (3.27 KB)

(Just look at the schematic view in the Fritzing attachment. I should probably have posted differently.)

Use an opamp

I have used some very low power op-amps which I have actually powered
from the 1.8 volt ADC reference voltage. This means they *can't*
drive the ADC inputs to more than 1.8 volts.

They are wired up as simple voltage followers so the output voltage
exactly follows the input voltage. The op-amps are TI LM10s. It's
been working for a year or more now and the BBB is all working still.

The LM10 op-amps can handle quite large input voltages without damage.


I also got microchip 6002, 6004 recommended in another thread. Almost 1/10 the cost but I see features in the LM10.

I’m also looking at low cost, when possible, so building a toolbox of circuits, like Forrest Mims Engineers Notebook. Extending to 1.8v logic.

Fred Kerr (mobile)