This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMH6628QML-SP: How much does performance/function degrade for total supply voltage below 5V?

Part Number: LMH6628QML-SP
Other Parts Discussed in Thread: OPA2822, OPA2652, OPA2677, LMH6628,

Hi experts!

My customer has a design where they had been planning to use this part with a 5V single supply. They recently realized this is right at the low limit of the allowed supply voltage range, and would like to know what the device performance/behavior would be if the supply voltage is as low as 4.5V.

Is any data available showing performance rolloff with supplies below 5V?

Thanks,

Jim B

  • Hi Jim,

    just run a test by your own and supply the OPAmp with a variable supply voltage from +5V down to let's say +3V. Also change the ambient temperature by putting the circuit into the oven. Then you get a feel about what's happening very quickly :-)

    Kai 

  • Doesn't help you for space Jim, but the equivalent part they were copying was the OPA2822. That was one of the 1st 3 parts on the BB CBC10 process along with the OPA2652 and the wildly successful OPA2677. 

    I also messed up that min supply there holding it at 5V instead of say a 5% low spec. These are not RRout devices so you don't have much swing going below 5V. Slipping below 5V, your main concern is the supply current setup ckt shutting off or dropping off a cliff, I did put this plot in showing I/O swings vs supply going down to 4V total, implying that works - but no guarantees, nor on the LMH6628 it seems. 

  • Hi team

    Can a product owner for the LMH6628QML-SP comment on the device functionality and performance with total supply of 4.7V?

    My customer believes they can ensure the supply voltage minimum will be 4.7V in the application and redesigning the system for a different amplifier will cause significant schedule/cost impact. 

    Please let me know ASAP.

    Thanks,

    Jim B

  • Well Jim, 

    Whomever that might be they have none of the original IC designers around to help. In any case, couple of more steps here - 

    1. Expected junction temp range would be helpful

    2. Lacking IC designers, the high speed apps guys could get the commercial EVM and ramp the supply down measuring supply current. It would be useful to see where it shuts down - if it ramps down linearly  to say 4V, that would be more comforting than falling off a cliff at say 4.5V. 

    3. Sometimes the ATE test flow includes a min supply test that is not reported, might check to see if that is part of the test flow (commercial or space). 

  • Also, from an applications perspective, there is not much swing available on 4.7V supply. worst case output headroom looks to be 1.9V on each side, so, if you center up the output at 1/2 supply, you only have a for sure 2.35V +/-0.45V swing available. 

  • Hello Jim,

       Michael is correct, we do not have plots for supplies under the recommended range in the datasheet. There would be no guarantee of specified datasheet performance under 5V supply range. I also could not find any other plots or information of the device below the recommended supply range. What we could do is as Michael mentioned which is measuring the supply current and output range at 4 - 4.5V power supply with a commercial EVM. 

    Thank you,

    Sima