SN74LXC2T45-Q1: Output rise and fall times

Chandan Raveendra

Part Number: SN74LXC2T45-Q1
Other Parts Discussed in Thread: SN74AXC2T45, TXB0102, TXB0304

Can I know what is the output rise and fall time or slew rate of the device at 1.8V supplies and 50pF cap load.

I am also looking for a buffer/ level shifter with following specs:

1.Bidirectional (auto-direction sense priority)
2.Operating voltage : 1.8V
3.Output rise and fall time: below 3ns for 50pF cap load

Can I get help to choose a product with above specs?

over 2 years ago

+1 Clemens Ladisch over 2 years ago

Guru 286730 points

See [FAQ] What is the output transition rate for a logic device?

Why are you referring a -Q1 device? Do you need automotive qualification?

At 1.8 V, the SN74AXC2T45 has the most drive strength. Auto-direction sensing is not possible for a buffer.

0 Chandan Raveendra over 2 years ago

Prodigy 45 points

Thanks for the post.
I need a level-shifter in one of my applications, placing it in-between the microcontroller and an external FPGA. Here trying to improve the down-shift the FPGA signal level from 3.3V to 1.8V (worst case 1.65V) using a level shifter. I have a transition time constraint of below 3ns for a 50pF load and need auto-direction sense feature.
Any latest products from TI with this specs?

0 Clemens Ladisch over 2 years ago in reply to Chandan Raveendra

Guru 286730 points

You can try the TXB0102. Please note that it requires short traces and cannot drive any pull-up/-down resistors.

0 Chandan Raveendra over 2 years ago in reply to Clemens Ladisch

Prodigy 45 points

Apparently I will be measuring the output signals in Tek Logic Analyzer and these probes have 20k pull down.
Kindly request to suggest an alternative

+1 Michael Ikwuyum over 2 years ago in reply to Chandan Raveendra

TI__Mastermind 34065 points

Hi Chandan,

Auto sense bi-directional devices are not designed for optimal performance with external pull ups and pull downs. However, I would further suggest TXB0304 (see section 8.4.2 of the datasheet per the Voh tolerance for your case), thanks.

Best Regards,

Michael.

0 Chandan Raveendra over 2 years ago in reply to Michael Ikwuyum

Prodigy 45 points

Thanks Michael and Clemens

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SN74LXC2T45-Q1: Output rise and fall times