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LT1715 window comparator query.

Category: Hardware
Product Number: LT1715


I have some questions about the function of window comparator of LT1715.
Please check if the attached circuit diagram is working well.
I want the out put of LT1715 to be logic high  when the input of LT1715 is between 1.0V  and 10.0V
1. VEE=0.0V, VCC=12.0V, +VS=3.3V
2. the range of Input voltage= 0.0V ~10.5V .​
3. OUTA and OUTB must be logic High when the input voltage is between 1.0V and 10.0V .
1. Is "VCC=12.0V and VEE=0.0V" valid ?
2. How much is the internal impedance of LT1715?
   Could I connect directly to the input terminal of LT1715 with the output voltage of AD5764 ( DAC ) without the resistance ?

Best Regards,
DS Jang
  • Hi DSJang,

    Having a quick look on your circuit, I don't see any issues with it.
    Though, your resistor network at the input side is blurred and I'm not sure if this configuration will give you the expected trip points. Can you give a clear picture with it?
    Because on the application stand point, this sets the trip points you want to have (1V to 10V).
    Have you tried playing around with LT1715 in LTSpice? the model is available and you can configure it to see the expected behavior of your schematic design.

    For the rest of the questions, VCC = 12V and VEE = 0.0V is valid based on the datasheet, and I don't see any problems directly connecting it with the AD5764's voltage output.

    Hope this helps DSJang.

    Best Regards,

  • Hi Dann,
    I am satisfied with your reply.
    Thank you for double-checking the contents as shown in the data sheet below.
    <On the data sheet of LT1715 >
        1. The following rules must be adhered to in any configuration: 2.7V ≤ (VCC – VEE) ≤ 12V . (page 9)
        2.  Source impedances should be kept low, preferably 1kΩ or less.  (page 11)
    Thank you again.
    Best Regards,
    DS Jang​
  • Glad to be of help DDJang.

    Let me know if you have more questions. Slight smile
    Thank you!

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