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Original question:

AM26C32: AM26C32MWB For Single Ended Application

AM26C32: AM26C32MWB For Single Ended Application

John Roy94
Prodigy 180 points
Part Number: AM26C32

Thanks Max, 

One more thing I forgot to mention. We'd like to change the behavior of the fail safe inputs such that an open input on the A terminal will output a '0' (low signal). To do this, we were considering a 10k pull down resistor on the A input (+3.3V I/O signal). However, the spice model of the input structure shows a small voltage differential between the two input circuits (A/B inputs with B input held at +1.5V w/divider). A 1k pull down seems to work better to provide a larger voltage differential. 

Thoughts here? 
Thanks,
John

  • 0
    TI__Guru 62920 points
    Hi John,

    Sorry I didn't get back to you on that other thread - I remember writing something up but I guess I never hit "send." I can see how a lower pull-down resistor would be helpful, though. Internally this device has a pull-up resistor on the A line and a pull-down resistor on the B line (so that the undriven state produces a "high" output), so the external resistors would need to overcome this. The internal pull-up is fairly weak (the datasheet specifies 288 kOhm as the nominal value), but the smaller you can get the ratio between the external and internal resistors the more effective your external resistances will be at establishing a suitable negative differential offset.

    Regards,
    Max