SN74LVC1T45: Resistor at DIR pin

Panomporn Kluebpuang

Part Number: SN74LVC1T45

Tool/software:

Hi there,

Refer to SN74LVC1T45, this is about the pin DIR. I saw some design put resistor between DIR pin to GND but some design connect DIR pin to ground directly.

Can you please advise what difference between "connect R to ground" and "Connect DIR to ground directly"?

Thanks,

Dan

7 months ago

0 Clemens Ladisch 7 months ago

Guru 316510 points

The device itself does not need a resistor. You can add one if you want to change the value during debugging.

0 Atlant Schmidt 7 months ago

Expert 1715 points

Some designs use a so-called “soft ground” (grounded through a resistor rather than hard-wired to ground) so that an automatic board tester can change the state of a pin (so, for example, change the state of the DIR input on this device).

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SN74LVC1T45: Resistor at DIR pin