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LM3886: Potential operation at -40C

Part Number: LM3886
Other Parts Discussed in Thread: TPA3116D2-Q1, TPA3255-Q1

We have been using the LM3886 with great results for over 15 years.  Some new applications are inquiring about use at industrial temperature ranges.  While the device storage condition is sufficient at -40C to 85C, the operating conditions fall a bit short.  What is the nature of any problems operating below the specified -20C.  Are there any reliability concerns, or is it that some of the specifications would not be met?  And if so which ones?

  • Hi Brian,

    I'm glad to hear that you all have been enjoying the LM3886! This device was developed a number of years ago so I wouldn't be able to give you the exact reason the choice of -20C was decided to be the minimum operation limit, but your intuition is likely correct. Either their is reliability concerns with operating below -20C, the device doesn't meet the specs set in the datasheet, or both. Either way, I can't recommend to you to operate the device outside of the datasheet specifications!

    That said, I can help you on finding an alternative device! We have a number of automotive rated amplifiers that operate down to -40C. 

    Best Regards,

    Robert Clifton 

  • Unfortunately not what I was hoping for, but a fair answer regardless.  Still this question will likely get asked again, so it seems worthwhile to try and pick a couple alternatives that we could do some testing.  Overall we are looking of course for similar specs, but one in particular is stability driving a low impedance load in the range of 1.2 to 3 ohms.

  • Hi Brian,

    Well with the operation need to have a wide range of operating temperatures, so the automotive devices would be a good start. I'm not sure what your power supply voltage is. Can you share? Also what the output power needed for the signal will help too.

    The TPA3116D2-Q1 might be able to work. The minimum impedance is 1.6ohms in the datasheet. However the minimum impedance comes from ensuring that the amplifier doesn't encounter current clipping (and overcurrent) before voltage clipping. This is why I need to know how much power you need to drive the impedance load. 

    Another amplifier that might work is the TPA3255-Q1. This device allows high voltage power supplies and can drive the impedance to high power levels.  

    Best Regards,

    Robert Clifton 

  • Hi Robert,

    With the LM3886 we use +/-15V supplies, but the TPA3116D2-Q1 looks like the right ball park for voltage and power.  Switching to a single 24V supply would be reasonable.