SN74LVC1G34: high speed clock buffer requirement

SONU GOYAL

Part Number: SN74LVC1G34
Other Parts Discussed in Thread: SN74AUC1G125, SN74AXC1T45

Can we use this buffer for 210 MHz clock? We have two clock of 210MHz, for that we need buffer. Level of one clock is 1.8V and second clock level is 3.3V

So please confirm can this part be used or not?

over 6 years ago

0 Dylan Hubbard over 6 years ago

TI__Mastermind 45725 points

Hi Sonu,

This device won't be able to handle that speed. the SN74AUC1G125 would be a good device for the 1.8 V clock buffering but since the supply only goes up to 2.7 V it won't work for the 3.3 V operation. The SN74AXC1T45 is a dual supply voltage level shifter, but if both supplies are tied together then it maybe able to perform this clock buffering. I recommend getting an EVM to evaluate, and also include the expected load as that will play a big part in what frequency the device can achieve.

0 SONU GOYAL over 6 years ago in reply to Dylan Hubbard

Intellectual 530 points

Hi,

Thanks for your reply. I checked both datasheets but I did not get any information to check it can work upto high frequency. Please let me know how to verify these devices can work for 210MHz supply

0 SONU GOYAL over 6 years ago in reply to Dylan Hubbard

Intellectual 530 points

Hi Dylan Hubbard

Thanks for your reply. I checked both datasheets but I did not get any information to check it can work upto high frequency. Please let me know how to verify these devices can work for 210MHz supply

0 Clemens Ladisch over 6 years ago in reply to SONU GOYAL

Guru 316690 points

The SN74AUC1G125 datasheet says that at 1.8 V and with a 15 pF load, the propagation delay is at most 1.5 ns. So you should have at least this distance between two signal edges. A square wave has two edges per cycle, so the frequency is 333 MHz.

The SN74AXC1T45 has a worst-case propagation delay of 4 ns at 3.3 V; this corresponds to 125 MHz.

Using the propagation delay underestimates the frequency because it is possible to change the input signal even when the transition at the output is not yet complete. Furthermore, smaller capacitive loads can be (dis)charged faster. So to find out whether the SN74AXC1T45 can handle your clock, you have to actually test it.

0 Dylan Hubbard over 6 years ago in reply to Clemens Ladisch

TI__Mastermind 45725 points

Hi Sonu,

Here's an FAQ which will help you get an estimate of what the device can handle:

https://e2e.ti.com/support/logic/f/151/t/742805?tisearch=e2e-sitesearch&keymatch=faq%3Atrue

But to truly know, you will have to test it as Clemens mentioned.

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SN74LVC1G34: high speed clock buffer requirement