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OPA2333: the output saturated level is far from rail-to-rail expectation

Hank Lin
Intellectual 1165 points
Part Number: OPA2333

Tool/software:

Dear team,

When we doing the experiment with the circuitry in below:

the non-inverted amplifier is powered with the positive supply 3.3V and negative supply to ground.

no load testing, so we expect less swing from power rail caused by I_load.

the input V+ = 2V DC voltage, R307 = R309 = 1kOhm.

The output voltage is expected to be close to 3.3V, with few tens mV swing, however the output swing is larger then the expectation.

May I know without the load, what is the normal range of the output voltage swing, which is not noted in datasheet?

Best regards,

Hank Lin

  • +1
    TI__Guru 63700 points

    Hank,

    The linear output range of OPA2333 is specified in the conditions of AOL to be 100mV from either rail - see below.

    However, your circuit is configured in gain of 2 and for this reason for Vin=2V, Vo cannot get to 4V on 3.3V single supply - see below.

  • 0 in reply to Marek Lis
    TI__Intellectual 1165 points

    Dear Marek,

    thanks for your support.

    the purpose of tuning the gain to let the output saturated is to shows the output swing from rail voltage.

    Best regards,

    Hank Lin

  • 0 in reply to Hank Lin
    TI__Guru 63700 points

    If you look at OPA2333 output fully saturated (non-linear) condition, then with 10k load it should get within 50mV - see below.

    You may simulate the datasheet condition on the left below with 10k load (Iload=247uA) confirming 50mV output swing to positive rail while for 1k+1k load (Iload=1.56mA) on 3.3V supply the output gets within 165mV below positive rail - see below.