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Original question:

TL071: different X-ray between datecode 2019 device and 2023 device

TL071: Selection recommendation

Lumina Gui
Expert 2955 points
Part Number: TL071
Other Parts Discussed in Thread: TPS65130, , TLV1811, TLV1805,

Dear TI Teams,

One of our project requires the implementation of 12V DC input and ± 12V AC output to power a screen, and the current is no more than 10mA. We are planing to using TPS65130 and TL071 to realize it. The requirement diagram is as follows:

Can you help confirm if this is available? Or is there any better suggestion for this application?

Thanks,

Kind Regards

  • 0
    TI__Genius 11820 points

    Hi Lumina, 

    Do you have a schematic or more details on the application use case for the TL071? 

    It would be helpful to understand the following:

    • Supply voltage
    • Expected Input signal waveform
    • How the input stage is configured (any passives connected between TL071 and TPS65130) 
    • Load connected on the output stage 
    • What is the frequency of the output waveform? 

    Please let me know if you have any questions.
    Thank you!

    Best Regards,
    Ashley

  • 0
    Guru 270970 points

    The TL071 is an analog amplifier (so it would have slow edges) and does not have rail-to-rail outputs. A comparator like the TLV1805 or TLV1811 outputs a digital signal at its power rails.

  • 0 in reply to Ashley Kang
    Expert 2955 points

    Hi Ashely,

    Pls check the reply for your question as below:

    Ashley Kang said:
    Supply voltage

    +12V DC & -12V DC;

    Ashley Kang said:
    Expected Input signal waveform

    PWM at 3.3V level, with adjustable duty cycle and frequency;

    Ashley Kang said:
    How the input stage is configured (any passives connected between TL071 and TPS65130) 

    Sorry we cannot understanding what this means. The TL071 will connected with TPS65130 directly, so there should be no passives connected between them. TL071H looks more suitable.

    Ashley Kang said:
    Load connected on the output stage

    The load is a ground glass screen with a load current of 10mA, and its transparency will change after passing through AC power;

    Ashley Kang said:
    What is the frequency of the output waveform?

    In theory, 50Hz would be more suitable.It's related to the PWM frequency of the input operational amplifier and should be adjustable. Both sine wave and square wave are acceptable, and we have tested that the effect of sine wave will be better.

    Thanks,

    Kind Regards

  • 0 in reply to Lumina Gui
    TI__Genius 9616 points

    Hi Lumina,

    TL071H will likely perform better than TL071 in terms of output swing, but this device will still struggle to drive close to the supply rails with +-10mA current output. 

    Is it necessary to drive the output to exactly +-12V? 

    In short, no amplifier will be able to drive the output all the way to the supply rail, but some amplifiers will be better at driving output current with respect to output voltage. 

    The datasheet has a graph, typically called a claw curve which demonstrates this effect:

    TL071H sourcing

    TL071H Sinking:

    These are both typical plots, but we can interpolate from the curve that the output could typically swing to a max output voltage of VCC-.6V at 10mA and a low voltage of VEE+.5V at 10mA current at 25C. In your example, this would typically result in an output swing of +11.4V to -11.5V output.

    Would this performance be acceptable to the application?

    The solution to this problem is to design supply rails which are higher than the intended output voltage you are trying to generate on the amplifier output. 

    For example, if you used +-15V supply rails, you would have ample headroom from the rail to generate a +-12V output signal even when driving heavy current loads.

    Please let me know if you have any questions.

    Best,

    Jacob