SN74LVCH16T245: Effect of transient Loss of VCCA or VCCB

Pierre Izard

Part Number: SN74LVCH16T245

Hello,

I haven't seen anything about the effects of transient loss of a VCCA or VCCB power supply in the datasheet.

In our design, there may possibly be the loss of one of these voltages (3.3V and 1.8V) for a maximum time of 65ms.

Can you confirm that there will be no other effect than the possibility of having the outputs in an erroneous state and this regardless of:

the power supply configuration: - VCCA = 3V3 and VCCB = 1V8 or VCCA = 1V8 and VCCB = 3V3,
or the direction, from B to A or from A to B.

Thank you in advance,

Best regards

Pierre

over 1 year ago

0 Michael Ikwuyum over 1 year ago

TI__Mastermind 25340 points

Hi Pierre,

Per the datasheet's Vcc Isolation and Ioff feature, if one of the supplies are at GND, both I/O will be in high impedance hence preventing an unknown state; as well as disabling the I/O and preventing backflow of current while the device is partially powered down. Hence, there should be no concerns, thanks.

Best Regards,

Michael.

+1 Clemens Ladisch over 1 year ago

Guru 258850 points

If a supply voltage is below the minimum of 1.65 V but above GND, and if /OE is low, then correct operation is not guaranteed, i.e., the outputs might output a wrong value.

The device will not be damaged (this would require exceeding any absolute maximum rating).

0 Pierre Izard over 1 year ago in reply to Clemens Ladisch

Prodigy 140 points

Thank you all for your answers.

Looking at the logic diagram, I don't think, either, that a reversal of direction is possible during the transient loss of VCCA: initial configuration B towards A with DIR tied to GND => no possibility of emitting an output signal on B during transient VCCA loss.

Best regards

Pierre

0 Pierre Izard over 1 year ago in reply to Pierre Izard

Prodigy 140 points

Could you confirm?

+1 Clemens Ladisch over 1 year ago in reply to Pierre Izard

Guru 258850 points

If V_CCA is below the minimum of 1.65 V but above GND, then there is no guarantee that DIR is handled correctly.

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SN74LVCH16T245: Effect of transient Loss of VCCA or VCCB