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LM293: Unused pin connection

Jim Tsai
Expert 4470 points
Part Number: LM293
Other Parts Discussed in Thread: LM339, TL331, TL331B

Hi,

I use pin5/6/7 but pin 1/2/3.

How to connect pin1/2/3? Floating? tie to GND?

  • 0
    TI__Mastermind 49966 points

    Hello Jim,

    Please see section 5.1 of the LM339 Family Application note:

     https://www.ti.com/lit/an/snoaa35a/snoaa35a.pdf

    My recommendation is to tie one pin 3 directly to pin 4 ( to the GND)  pin, and connect pin 2 through a 1Meg resistor. The input bias current will generate a small voltage across the 1M resistor and force the output low.

    The appnote adds series resistor to the inputs to limit any transient currents. If pin 3 and 4 are tied directly together - there should not be any large transient differences between them.

    If you just need a single device, the TL331 or TL331B is the single channel version.