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TLC339: Question regarding the reason for adding a DC source at the output of this comparator in this reference design.

Part Number: TLC339

Hello, I am looking at the circuit on page 50 of this presentation (Microsoft PowerPoint - Sec2_RemoteSysMonitor_Print.ppt ( I am unable to understand the reason for use of this battery and the 2k resistor here. Would really appreciate if you could help me out.

  • Hello,

    The TLC339 is an open drain output comparator that requires a pull-resistor to a voltage to make the input go "high".

    Without the V3  voltage source, the output would never go "high". Since it is a 5V source, the output will go "high" to 5V.