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NE5532: NE5532 Output Current

Jason Williams57
Prodigy 40 points
Part Number: NE5532

I have an application using an NE5532 as an audio line driver (mid-rail biased, single-ended 12V supply) and have a question regarding the output current specs. Under electrical characteristics on the datasheet, the output short circuit current is listed as 38mA, which matches with the 15Ohm resistors in the block diagram of section 8.2 (600mV/15 = 40mA at current limiting).  Then under Vopp, assuming 24V swing into a 600 Ohm load, I get a current amplitude of (12V/600) = 20mA, which I am assuming is a guaranteed spec. However, also listed under short circuit current is a minimum value of 10mA. In another source here on the forum I found a value for "output current" for this amplifier listed as 25mA. Does the minimum short circuit current mean that some NE5532's can only output a maximum of 10mA?   I am hoping to get some clarification as to what to use as a reliable value for maximum output current for design purposes, ideally when operating from a single 12V supply.  

  • 0
    TI__Guru**** 157036 points
    Jason,

    20mA is supported at room temperature (25C) as you said 12V/600 ohms. The 10mA minimum has at least 10mA margin; also at 25C
    Current limit decreases with higher temperature. This is good because shorts tend to increase temperature.

    25mA assumption is fair, It is reasonable to expect at least this much current from -40C to 85C
    Nevertheless, the data sheet doesn't directly support this claim.

    How much current do you need? What happens if the device can't fully meet that value?
  • 0 in reply to Ron Michallick
    Prodigy 40 points

    Hi Ron,

    Thanks for the reply. 20mA would suffice for the application, and in testing I haven't yet come across any issues at current output levels up to this value in the amps I've used. But the datasheet short circuit output current got me wondering if maybe other NE5532s wouldn't be able to supply the required current, and it seemed everyone i asked had a different interpretation of the datasheet specifications. Based on the fact that according to Avd specs, slew rate starts being affected a 5mA (Vo=10V into 2kOhm load) and a minimum short circuit output current spec of 10mA, I had other engineers saying it would be a bad idea to use this amp above 5mA. This got me thinking about whether I should consider a different part, so I thought I would contact TI directly.  Distortion and not meeting output specifications would be the results of reaching maximum current output, max operating temp would be 50C and as mentioned above, power supply is 12V single-ended with mid-rail bias.

    So based on your statement above, you're saying that I should have no issues using this device to source/sink 25mA if required across the full temperature range?

  • 0 in reply to Jason Williams57
    TI__Guru**** 157036 points

    Jason,

    It is odd that Vopp supports 20mA with a 3V headroom yet a short has a minimum of 10mA. So I checked old data sheet revisions and saw that the 10/60 limits were added in May of 2000. But why was that? I checked for NE5532 competitors at Digikey and saw that other device also has 10/60 limit. So someone replicated the limit and someone else created the original unwarranted 10mA minimum. In any case, 10mA just doesn't make sense.

    The Avd spec doesn't show any weakness, but it does indirectly support at least 16.7mA current drive across full temperature range as DC gain is >10k

    Here is a 50 amplifier char result for NE5532.

                    IOS-        

       LotID.Tmp            Mean      StdDev     Mean-3s     LowRead      HiRead     Mean+3s    Reads

    -----------------+---------------------------------------------------------------------------------

            -40C    |  -48.027mA   105.198uA   -48.342mA   -48.096mA   -47.607mA   -47.711mA       50

            0C      |  -48.044mA    65.629uA   -48.240mA   -48.218mA   -47.974mA   -47.847mA       50

            25C     |  -48.015mA   119.972uA   -48.374mA   -48.096mA   -47.607mA   -47.655mA       50

            70C     |  -46.818mA     1.537mA   -51.429mA   -48.096mA   -41.748mA   -42.207mA       50

            85C     |  -44.633mA     1.124mA   -48.005mA   -45.654mA   -40.283mA   -41.261mA       50

    -----------------+---------------------------------------------------------------------------------

                IOS2+    

       LotID.Tmp            Mean      StdDev     Mean-3s     LowRead      HiRead     Mean+3s    Reads

    -----------------+---------------------------------------------------------------------------------

            -40C    |   47.194mA   390.580uA    46.022mA    46.730mA    48.002mA    48.365mA       50

            0C      |   47.032mA   395.059uA    45.846mA    46.094mA    47.525mA    48.217mA       50

            25C     |   46.641mA   310.048uA    45.710mA    46.094mA    47.366mA    47.571mA       50

            70C     |   46.482mA   298.172uA    45.587mA    46.094mA    46.889mA    47.376mA       50

            85C     |   46.434mA   316.390uA    45.484mA    46.094mA    46.889mA    47.383mA       50

  • 0 in reply to Ron Michallick
    Prodigy 40 points

    Hi Ron,

    Great, thanks for that information, good to know this amp will work fine in my application. Hopefully the datasheet will be corrected to fix that error.

    Actually I do have one more  question regarding one of your responses above. The datasheet states a worst case 12V/600 = 20mA at 25C under Vopp, and yet you say it is reasonable to expect 25mA over the full range of -40 to 85C.  Can you elaborate on this?  These statements are conflicting.