SN74LVCR16245A: Regarding SN74LVCR16245A buffer

Archana Rao

Intellectual 915 points

Part Number: SN74LVCR16245A
Other Parts Discussed in Thread: SN74LVCHR16245A

Hi,

We are using SN74LVCR16245A buffer in our design.

Wanted to know if SN74LVCR16245A has bus hold circuit capability.

I was comparing SN74LVCR16245A vs SN74LVCHR16245A. Both the datasheets mention bus hold circuit capability.

Initially, I was of the notion that only SN74LVCHR16245A supports bus hold capability due to 'H' added in the part number.

But now, am confused after looking through the datasheet. Can you please confirm if this information is correct?

If bus hold capability is supported, why is it that pull up/down resistors are not recommended on this type of circuit?

What happens if we place pull up/down resistors?

Regards,

Archana Rao

over 8 years ago

0 Clemens Ladisch over 8 years ago

Guru 318660 points

The H datasheet mentions the bus-hold function in many more places, and actually specifies a value for I_I(hold).

The SN74LVCR16245A does not have bus hold. The datasheet appears to have a copy/paste error.

0 Archana Rao over 8 years ago in reply to Clemens Ladisch

Intellectual 915 points

Hi Clemens,

Thank you for your quick reply.
In case, if I use SN74LVCHR16245A (with bus hold circuit) in my design, why are pull up/downs not recommended to be used on input/output lines as per datasheet?

What happens if I place pull up/down resistors on these lines?
Will it interfere with my circuit operation?

Regards,
Archana Rao

0 Clemens Ladisch over 8 years ago in reply to Archana Rao

Guru 318660 points

Bus-hold circuits are the equivalent of a pull-up/-down resistor, so if you have an external pull-up/-down, it must be stronger to be able to override the internal one. See section 6.3 of Bus-Hold Circuit (SCLA015) for details.

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SN74LVCR16245A: Regarding SN74LVCR16245A buffer