TXS0108E: Slew Rate △V range consult

Stanley Dai

Expert 5810 points

Part Number: TXS0108E

Hi Team,

What's your △V range for measuring the slew rate here to customer when doing rise/fall rate calculation? Thanks

Best,

Stanley

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 243820 points

For the control input, it's measured between V_IL and V_IH.

For the I/Os, it matters only until the triggering threshold of the edge accelerators has been reached. The datasheet does not mention what these voltages are.

Please note that the ΔV/Δt limit applies to all points of the edge, i.e., it would not be allowed to have a flat plateau in the middle of the edge.

0 Stanley Dai over 2 years ago in reply to Clemens Ladisch

TI__Expert 5810 points

Hi Clemens,

Thanks for your helps.

According to your comments, so customer only needs to care about the accelerators' edge marked by red cycle in below waveforms,right?

And could you pls further explain what's the internal mechanism of the internal edge accelerators? Thanks.

Best,

Stanley

0 Clemens Ladisch over 2 years ago in reply to Stanley Dai

Guru 243820 points

No, what matters is the flattest part of the edge, before the accelerator has triggered.

The internal mechanism are explained in the Guide to Voltage Translation With TXS-Type Translators.

0 Stanley Dai over 2 years ago in reply to Clemens Ladisch

TI__Expert 5810 points

What if customer cannot meet this slew rate spec, what's the risk they will meet, VCC short through w/ GND during operation?

0 Dylan Hubbard over 2 years ago in reply to Stanley Dai

TI__Mastermind 42640 points

Hey Stanley,

Are these push pull signals? That spec is mostly to bound the data rate and other timing specs for push pull signals. Based on the scope shot I wouldn't expect there to be any issues, but if the transition is slow enough there could be oscillations. I've only seen this with transitions in the hundreds of ns/V range.

0 Stanley Dai over 2 years ago in reply to Dylan Hubbard

TI__Expert 5810 points

Hi Dylan,

What's your judgement standard for above waveforms I shared? Customer may need the standard to do following judgements.

Best,

Stanley

+1 Dylan Hubbard over 2 years ago in reply to Stanley Dai

TI__Mastermind 42640 points

Hey Stanley,

I eluded to it in that post. I see oscillations when the transition is very slow ("in the hundreds of ns/V range") and the signal in the scope shot reaches VCC within ~130 ns. This is only based on testing that I've done before, so there really isn't anything the customer can judge on their own (and this doesn't mean it couldn't happen with quicker transitions). They should just try to meet the specs, and if they can't they either need to accept the risk or find another suitable device.

0 Clemens Ladisch over 2 years ago in reply to Stanley Dai

Guru 243820 points

There is no risk. If that 10 ns/V limit is exceeded, then the input signal does not qualify as "push/pull driving". The only consequence is that the guaranteed maximum data rate is lower (see the switching characteristics table).

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TXS0108E: Slew Rate △V range consult