SN74LXCH8T245: Schmitt-Triggers on Data Inputs

Ion Tihi

Part Number: SN74LXCH8T245

The datasheet (SCES917B – DECEMBER 2019 – REVISED MARCH 2021) states in Item 1 Features: "Schmitt-Trigger Control Inputs Allow for Slow or Noisy Inputs".
But what about Schmitt triggers on Data Inputs? They are present on the Functional Block Diagram, but there is no explicit mention of this important feature in the description.

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 317370 points

The recommended operating conditions table explicitly says that the data inputs have V_IH/V_IL specifications, which implies that there is no guaranteed hysteresis.

Apparently, the functional block diagram should not show Schmitt triggers for the data inputs.

0 Ion Tihi over 3 years ago in reply to Clemens Ladisch

Prodigy 10 points

Thank you for the fast response.
Could I kindly get an exact answer without "apparently"?

P.S. Any "real" Schmitt-Trigger devices also have VIH/VIL specifications.

0 Dylan Hubbard over 3 years ago in reply to Ion Tihi

TI__Mastermind 46045 points

Hi Ion,

Let me look into this.

0 Karan Kotadia over 3 years ago in reply to Dylan Hubbard

TI__Genius 16735 points

Hi Ion,

There are no schmitt-triggers on the data inputs. The functional block diagram is incorrect. I will be updating it.

The data inputs have VIH/VIL specs which we use for standard inputs. When the inputs have schmitt-triggers, they have Vt+ and Vt- specs to indicate the hysteresis.

Regards,

Karan

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SN74LXCH8T245: Schmitt-Triggers on Data Inputs