TXS0102-Q1: follow up question on FAQ why TSX0xxx VIL/IH so stringent

Dongbao Zhou

Part Number: TXS0102-Q1

hello,

One follow up questions on why TXS010x VIL/VIH specification so stringent, i can understand the logic that the downstream device input requirement are taken into consideration. If we don't consider the Vol/voh dependency on Vil/Vih, what are the real VIL/VIH spec?

Regards,

Dongbao

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 316760 points

For all input voltages below V_CCA, the TXS works as an analog switch. For input voltages above V_CCA, the switch is open, and the output voltage is determined by the pull-up resistor. It does not make sense to specify V_IL/V_IH values for this behaviour.

0 Dongbao Zhou over 2 years ago in reply to Clemens Ladisch

TI__Expert 4170 points

hi Clemens,

Thanks for the feedback.

Now I can understand why Vil doesn't make sense due to the N-FET on until input voltage higher enough to turn it off, but why VIH spec doesn't make sense?

+1 Clemens Ladisch over 2 years ago in reply to Dongbao Zhou

Guru 316760 points

Sorry, my statement might have been too strong. While there is no logic low state, it is possible to define the switch-open state as high.(And when you want to know what input voltage you need to make the output high, this is certainly the correct answer.)

0 Michael Ikwuyum over 2 years ago in reply to Dongbao Zhou

TI__Guru 50676 points

Hi Dongbao,

In addition to Clemens' feedback, note that with the direct input to output connection architecture of the device; the provided specification in the datasheet is to help guarantee specified VOL and VOH levels.

Hence, if the VOL/VOH observed is acceptable; then there should be no concerns, as they are dependent on the current of the drivers per the application's IOL/IOH and ROH i.e VOL = VIL + (IOL*Ron) and VOH = Vcc - (IOH*ROH). Please see the referenced Factors Affecting VOL for the TXS and LSF Auto-Bidirectional Translational Devices, to help further clarify, thanks

Best Regards,

Michael.

Logic

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TXS0102-Q1: follow up question on FAQ why TSX0xxx VIL/IH so stringent