SN74LVCH8T245: Pull up/down on bus hold unidirectional buffer output

Srivatsa Kolhapur

Part Number: SN74LVCH8T245

Hi,

I wanted to follow up on thread . I understand that pull up or pull down on bus hold ill create voltage divider. Is it possible to have a Pull up or Pull down on output lines in a unidirectional buffer? just wanted to have outputs in known state when buffer is disabled.

Thanks

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 256820 points

Yes. A unidirectional buffer (e.g., SN74xxx541, SN74xxx244) completely disconnects its outputs when disabled.

0 Srivatsa Kolhapur over 1 year ago in reply to Clemens Ladisch

Prodigy 108 points

Hi Clemens,

Is there any possibility of fault after buffer is enabled?

0 Clemens Ladisch over 1 year ago in reply to Srivatsa Kolhapur

Guru 256820 points

The output impedance of LVC logic gates is about 12 Ω. So the effect of a typical pull-up/-down resistor with, e.g., 10 kΩ is negligible.

0 Srivatsa Kolhapur over 1 year ago in reply to Clemens Ladisch

Prodigy 108 points

Does the same apply to LVTH series too?

+1 Clemens Ladisch over 1 year ago in reply to Srivatsa Kolhapur

Guru 256820 points

LVT outputs are slightly weaker, but the principle is the same.

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SN74LVCH8T245: Pull up/down on bus hold unidirectional buffer output