SN74LVC1T45: Logic forum

Atlant Schmidt

Part Number: SN74LVC1T45

I'm trying to understand the power supply current that will be consumed by the SN74LVC1T45 Single-Bit Dual-Supply Bus Transceiver. The Data Sheet (included below) has parameters for ICCA and ICCB, each stated as 3 µA max absent any external load on the I/O pins. So far, so good.

But the Data Sheet also defines ΔICCA and ΔICCB parameters, each stated as 50 µA max. I don't understand what these parameters are trying to specify and there doesn't seem to be any discussion of these parameters in the rest of the Data Sheet.

Can someone please explain to me what these parameters are trying to illustrate/specify?

Atlant

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over 6 years ago

0 ShreyasRao over 6 years ago

TI__Guru 64400 points

Hi Atlant,

This is the delta Icc which defines the additional Icc current consumed when one of the input voltage is not at the rails ( Vcc or gnd). As the test condition suggests, the input is Vcc-0.6V. As long as the input voltage is at Vcc or gnd in your system, the delta Icc wouldn't matter.

0 ShreyasRao over 6 years ago in reply to ShreyasRao

TI__Guru 64400 points

please refer to the app note on understanding logic datasheet parameters.

Page 46 explains the delta Icc spec in detail.

0 Atlant Schmidt over 6 years ago in reply to ShreyasRao

Expert 1725 points

Shreyas:

> This is the delta Icc which defines the additional Icc current consumed when one
> of the input voltage is not at the rails ( Vcc or gnd). As the test condition suggests,
> the input is Vcc-0.6V. As long as the input voltage is at Vcc or gnd in your system,
> the delta Icc wouldn't matter.

Thanks! In my application, we're always holding DIR grounded (so the direction is
always B => A) and the B input is driven from CMOS sharing VCCB so it should be
rail-to-rail from the point-of-view of the SN74LVC1T45. All that means I can ignore
this parameter in my application, right? No cross-conduction owing to funky in-the-
switching-region input voltages.

Atlant

0 Atlant Schmidt over 6 years ago in reply to ShreyasRao

Expert 1725 points

This is a good reference:

https://www.ti.com/lit/an/scba004d/scba004d.pdf

Application Report SCBA004D–July 1994–Revised September 2016 Implications of Slow or Floating CMOS Inputs

0 ShreyasRao over 6 years ago in reply to Atlant Schmidt

TI__Guru 64400 points

Yes, that too is one of our most viewed app notes !