# Any reason why the MIC920 op amp should not be used in SINGLE SUPPLY mode?

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.

## 1 Answer

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.

• 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? May 12 at 6:28
• Sorry, just saw the rest of your comments. I understand. Not a good fit for a rail-to-rail single-supply op amp. May 12 at 6:29