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LMH7322: Latch feature

Jens Neumann
Prodigy 20 points
Part Number: LMH7322
Other Parts Discussed in Thread: TINA-TI

Hello,

we use the LMH7322 with the following supply voltage:

VCCI +5V
VCCO +2.5V
VEE -5V

We dont need the Latch feature, so we connect the #LE Pin via 10k to VCCO (2.5V).

My question: Is it allowed to connect the LE Pin via 10k to GND (0V), or must we connect the LE Pin via 10k to VEE (-5V)

At the Tina-Ti simulation it runs with LE via 10K to GND.

Kind regards
Jens

  • 0
    TI__Mastermind 23395 points

    Jens

    According to the EC table, if you ground the LE pin, that will enable the latch mode.  The latch enable voltage range is from VEE +1.4V (for your application that is -3.6V) to VCCO - 0.8V (for your application that is 1.7V).  Since ground is within that range, you would be enabling the latch feature.  I will need to investigate the model tomorrow, but I suggest you leave the pull-up on LE connected to VCCO as you previously had it.  However, you could also disable LE by connecting it to VEE as well since both of those conditions are outside the EC table range for enabling the latch function.

    Chuck

  • 0 in reply to Chuck Sins
    Prodigy 20 points

    Thank you for your answer

  • 0 in reply to Jens Neumann
    TI__Mastermind 23395 points

    You are more than welcome Jens

    In the meantime, we are still reviewing the model to see what improvements need to be made.

    Chuck

  • 0 in reply to Jens Neumann
    TI__Expert 4555 points

    Jens,

    To add to Chuck's response, it seems the TINA simulation does not model this properly. Even at split supply, connecting a 10k to ground on the latch pins should not enable latch but it still does.

    This is an error on the model and we will work on fixing this issue in the meantime. For now, I would recommend leaving it tied to VCCO so that you can see how the part should function as if latch were not enabled.

    Regards,
    Jonny