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Resistors for Enable/Disable

Hithesh
Genius 3290 points

Other Parts Discussed in Thread: AM26C32

How is the resistor value for an IC Enable/disable pin decided.
I always use 10K. But not sure how to calculate it .

The IC in question is am26c32, the enable ckt in datasheet already has a resistor. Is an external resistor to Vcc/gnd still required?

What is good engineering practice - connect /Enable directly to ground or thru a resistor.

  • 0
    TI__Expert 5055 points

    Good morning,

    "Good" practice for pretty much any IC would be to connect select/enable lines using a resistor to "pull-up" or "pull-down". The goal is to use the resistor to limit excessive current that might otherwise damage the IC. Unless you are doing massive production runs where every penny counts, and you can't afford to add "extra" resistors, using a resistor can do no harm.

    10k is a pretty typical value, and it should work fine for your application.

    That being said, you would have to consider the resistor value if you were using pull-up/pull-down resistors on data/clock lines (like I2C). In this case, the waveform will need to be able to change rapidly (i.e. square wave), and too high of a resistance value will prevent it from doing this.

    Hope it all helps.

    -Bryan