TXB0108: input sequence

ACGUY

Part Number: TXB0108

Hello E2E,

I have issue about TXB0108 on our customer board.
: When Vcca is 1.8V and VccB is 3.3V, OE is Low at initial state.
: 24-MHz clock input to 1.8V side.
: OE to be High.
: 3.3V side is not output nomally.

I think that this device should not be inputed before OE is set to High.
Is it correct?

Regards,
ACGUY

over 8 years ago

0 ShreyasRao over 8 years ago

TI__Guru 63230 points

Agguy,

would you please send schematic and the waveforms.
I want to understand more about the' 3.3V side is not output normal' statement.

what is the parasitic load cap and the probe cap when measured on the scope?

TXB is sensitive about the loading cap and have layout restrictions on the output trace length.

0 ACGUY over 8 years ago in reply to ShreyasRao

Guru 11170 points

Shreyas,

I do like to change the question.
When 24-MHz clock is input to 1.8 V side within 1 usec from OE-High-edge, is this device capable of normal operation?

Regards,
ACGUY

0 ShreyasRao over 8 years ago in reply to ACGUY

TI__Guru 63230 points

ACGuy,

Referring to the switching characteristics on page 8 of the datasheet, the enable time max for 1.8V operation is 1us( time from OE asserted to A/B) and hence I would say that the normal operation is not guaranteed when input is <1uS from OE edge.

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TXB0108: input sequence