SN74LVC4245A-EP: Unused pins

Yoshwa

Part Number: SN74LVC4245A-EP

Do we need unused I/O-pins of Ai and Bi to pull down to GND through resistors?

We could not specify I/O-pin functions of Ai and Bi; because those functions of input or output are depend on direction pin (2-pin) control.

What resistor value is recommended?

Is about 10 k ohm a possible choice?

over 7 years ago

0 Wade Vonbergen over 7 years ago

TI__Guru 62930 points

Yoshwa,
Unused inputs must be biased to valid level.
There is an application note that discusses this. Please see SCBA004.
In section 4.2, it discusses resistor selection for devices without internal busholders.
www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=scba004&fileType=pdf&keyMatch=SCBA004&tisearch=Search-EN-Everything

Regards,
Wade

0 Yoshwa over 7 years ago in reply to Wade Vonbergen

TI__Expert 4050 points

Wade-sann,

Many thanks for your reply.

Please confirms the following example to me.

Connecting both A1-pin and B1-pin to GND with 10-kΩ resitors are recommendable if A1 and B1 are not used.

0 Wade Vonbergen over 7 years ago in reply to Yoshwa

TI__Guru 62930 points

Yes, 10k will work fine. This will safely keep the inputs and outputs both at gnd regardless of direction or enable.

Regards,

Wade

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SN74LVC4245A-EP: Unused pins