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OPA2172: What is "Voltage output swing from rail" ?

ericsson sunshine
Prodigy 250 points
Part Number: OPA2172

Hi, crews:

I'm sorry, I am an user. And I'm surveying the datasheet of OPA2172.

Actually, at the beginning, I was trying to find out the voltage upper limit & lower limit of output offset (or say, Vol & Voh, high level output voltage & low level output voltage).

Then I found the parameter of "votlage output swing from rail" in OPA2172 datasheet, eg: it says typ=470mV @(Rl = 2K, Vs=+36V), after some short web surfering, I am still confused about what's the physical meaning of this parameter "Voltage output swing from rail" ? In the test condition, no input signal specified,  so does it affect the signal gain accuracy ? What's the difference when compared with the slew rate ?

Please tolerate me, if I asked a stupid question. I don't know the exact definition of "Voltage output swing from rail", there are many sayings , I am not sure which is right.

Thank you

Have a nice day!

  • 0
    TI__Guru**** 153306 points

    Ericsson,

    The table header says "At TA = +25°C, VS = ±2.25 V to ±18 V, VCM = VOUT = VS / 2, and RL = 10 kΩ connected to VS / 2, unless otherwise noted." The typical 470mV from rail has a supply of 36V (V+ = 36V and V- = 0V) and an output load of 2k. The other side of the resistor connects to 18V (VS/2). Typical VOL will be 0V+470mV= 470mV which is 470mV away from the negative power supply rail that is 0V. Typical VOH will be 36V-470mV =  35.53V which is 470mV away from the positive power supply rail that is 36V. The input differential during test is at least +/-100mV. However VOL and VOH don't need that an input that large. 

    Slew rate test does requires at least +/-100mV input signal; less input would result in slower slew rate.