SN74LVC244A: Freq

Shay Mor

Intellectual 870 points

Part Number: SN74LVC244A
Other Parts Discussed in Thread: SN74LVC74A,

hi,

what is the maximum frequency can I use with the SN74LVC244APWR?

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 317450 points

From the propagation delay, 1 / 7.2 ns = 138.9 Mbps.

But see [FAQ] What is the maximum data rate (or operating frequency) for a logic gate or buffer? The SN74LVC74A goes up to 150 MHz.

0 Shay Mor over 3 years ago in reply to Clemens Ladisch

Intellectual 870 points

hi,

how the propagation delay is related to the maximum frequency that I can transfer from the input to the output without damage in the harmonies of signal?

+1 Sebastian Muriel over 3 years ago in reply to Shay Mor

TI__Mastermind 18430 points

Hi Shay,

The most important factor to determine maximum speed of a logic gate is going to be capacitive loading at the output. Clemens used the max propogation delay (7.2 ns) at Vcc= 3.3V ±0.3V with a load of 50pF to calculate Fmax. For proper operation of the device, the input signal frequency can't transition faster than the device is able to switch at the output.

My recommendation is to use the IBIS model on the SN74LVC244A product page to run a signal integrity simulation. You can set your system requirements to see if your device can operate at your desired frequency. Below is a simulation I ran with a 30pF load, Vcc = 3.3V, and a frequency of 69.45MHz.

Regards,

Sebastian

Logic

Logic forum

SN74LVC244A: Freq