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Original question:

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

OPA145: OPA145 out put voltage required

kumar arun
Prodigy 20 points
Part Number: OPA145

Hi Texas team,

in 

OPA124UA is obsolete and  texas suggest replacement is OPA145 but in  OPA124UA output voltage mention 12 V and OPA145 output voltage mention " out put voltage swing from rail " = 250mV 

i need the output voltage of the OPA145  . can you help to provide the details and how you calculate out put voltage swing from rail to output voltage ? 

  • 0
    Guru 272680 points

    The OPA124 has a 12 V output with a 15 V supply, i.e., it requires 3 V of headroom.

    The OPA145 has rail-to-rail outputs, and needs much less headroom. The voltage drop depends mostly on the current; see figure 6-12.

  • 0
    TI__Guru 54241 points

    Hi Kumar,

    Thanks Clemens for the reply!

    kumar arun said:
    can you help to provide the details and how you calculate out put voltage swing from rail to output voltage ? 

    Captured image below is input Vcm and Vout swing comparisons between OPA145 and OPA124UA.

    For the low end of the input voltage, Vcm,  OPA145 can go as low as (V-) - 0.1V, which is much better than OPA124UA at approx. (V-) +5

    For the high end of the input voltage, Vcm, OPA145 can handle up to (V+) - 3.5V, and it is also better then OPA124UA at approx. (V+) -5. 

    For the output, OPA145 is close to rail to rail, but OPA124UA's output swing is rated +/-4V from the supply rails at 2kOhm load. 

    If you have additional questions, please let us know. 

    Best,

    Raymond