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LPV7215: about comparator application

Joyce Li
Intellectual 2170 points
Part Number: LPV7215


Hi Dear expert,

My customer adopts LPV7215 in their project. They uses LPV7215 as a comparator. Below is their schematic.

V+=5V, V-=0V. Vin+=5*100/103=4.85V

if GPS_ANT_power is connected, there will be 25mA current output, so Vin-=5V-15*25mA=4.625V. Then output will be high.

If GPS_ANT_power is not connect, Vin-=5V. Then ouptut will be low level.

Customer uses LVP7215 to check whether GPS_ANT is connected or not.

Please help confirm this application is correct. 

i also have a question about Feedback resistor. 1. Why this part is positive feedback 2. whether 150Kohm is proper?

thanks a lot for your support!

BR, Joyce

  • 0
    Guru 140200 points
    Hi Joyce,

    the circuit seems to work. But take care that the abolute maximum ratings shown in section 6.21 are never violated, not even during the power-up and power-down sequence.

    I would think about inserting a 1k current limiting resistor directly at the "IN-" pin, though. See section 7.3.1.

    R126 shall provide some hysteresis. But to work properly the input voltages should stay more away from the supply rails. This could be accomplished by modifying the voltage divider R129/R156 and by introducing a new voltage dividier directly at the "IN-" pin. This would also serve as a current limiting into the "IN-" pin, like the 1k resistor recommended above.

    Kai
  • 0 in reply to kai klaas69
    TI__Mastermind 26460 points
    Joyce
    you have not posted any further information on this post, so I am closing it. If you have further questions, feel free to hit reply and the post will be reopened.
    Chuck