0
\$\begingroup\$

I understand that practically any op amp can be used in single-supply mode as long as the application (interface, measurement, etc) does not require dual-supply for specific reasons.

  • Is there a reasons why the MIC920 (being a general purpose op amp) does not list single-supply (i.e. 0-5 V) as an option?

  • Is there a way to determine if it's rail-to-rail?

The planned use would be amplification of mV level positive-only pulse signals by 100-1000 times between 500 Hz - 20 kHz for reading by an MCU.

\$\endgroup\$
1
\$\begingroup\$

Look at the Maximum Output Voltage Swing.

With \$\pm\$5V supply voltage, the output range is \$\pm\$3V. So your output will not got to ground in a single supply, but will be stuck at a minimum voltage of at least 2V.
With \$\pm\$9V the datasheet is even more conservative and specifies a headroom of -2.8V.

These values are given for a load resisitance of 2k\$\Omega\$, so if your load will be high impedance, then the minimum output voltage will probably be a bit higher.
But the OpAmp is clearly not designed as a single supply device, as the output is not nearly R2R.


Figure 2-12 shows you the negative output voltage for \$\pm\$9V supply rails vs. output current - and even at 0mA the output will not go below -8V. So even with a really high impedance load your output would not be able to go lower than 1V above ground. enter image description here

\$\endgroup\$
2
  • \$\begingroup\$ Thank you for the explanation. So for example, if I use the conventional 3.3V single-supply from a MCU to supply the MIC920, would I get a 0-3V maximum output swing...basically a rail-to-rail output? \$\endgroup\$
    – TommyS
    May 12 at 6:28
  • 1
    \$\begingroup\$ Sorry, just saw the rest of your comments. I understand. Not a good fit for a rail-to-rail single-supply op amp. \$\endgroup\$
    – TommyS
    May 12 at 6:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.