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TLV274: Use TINA-TI to confirm gain margin and phase margin by changing load

Hung Ching Hsu
Expert 3086 points
Part Number: TLV274
Other Parts Discussed in Thread: TINA-TI, TLV271, TLV9154

Hi Team

My customer uses TLV274 as voltage follower.

My customer is referring the material(use TINA to confirm negative feedback stability, which is written in japanese) to confirm gain margin and phase margin. 

I think gain margin and phase margin will change if I change the value of load(R1 and C1). 

But even i changed the load(R1) from 100kohm to 10ohm(near to short), the gain margin and phase margin didn't change much.

Is this normal or there are something wrong with my schematic? 

Here's the photo of simulation and TINA-TI file as attached.

Thanks.

TLV274_phase margin_gain margin.TSC

  • 0
    Guru 140200 points

    Hi Hung,

    the simulation model of TLV271 from 2011 uses an old Boyle model. So, don't expect too much :-)

    Kai

  • 0
    TI__Genius 15410 points

    Hello,

    The circuit shown in the TINA-TI file is not how we recommend measuring the phase margin. I recommend watching our TI Precision Lab Videos on Stability for more information on how to simulate phase margin of a device. 

    In addition to the method used to simulate phase margin, the input must be biased up to mid supply when using single supply operation. As the circuit is currently configured the input and output are railed to the negative supply (GND). The op amp must be in a linear operating region. The other option is to add a negative supply voltage.

    Attached is the recommended circuit to use. I have removed the 10ohm load resistor because the TLV274 cannot output enough output current with a 10ohm load and 7.5V output voltage. 

    Have you considered looking at the TLV9154 for your design instead of the TLV274?

    TLV274_phase margin_gain margin_Edit.TSC

    Thank you,

    Tim Claycomb