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Original question:

LSF0101: LSF0101

SN74LXC2T45: SN74LXC2T45

Ishwar Sharma
Prodigy 160 points
Part Number: SN74LXC2T45

Tool/software:

Hi

We are looking the part SN74LXC2T45 for signal level translation. Propagation delay is our key parameter for design.

There is given Minimum propagation delay (with VCCA= 3.3 ± 0.3 V) as 1ns and Max propagation delay as 57ns (From A to B) with -40°C to 85°C and 36ns with -40°C to 125°C and min 1ns and max 33ns and 29ns respectively with temp. It is also decreasing (Max value) with VCCB increasing.

What is the key factor responsible for this propagation delay. What propagation delay we should consider here. Can you please help here to understand this. 

Can we change VCCB/VCCA supply in steps of 100mV with VCCA/VCCB (3.3 ± 0.3 V) fixed voltage respectively. We need to translate 3.3V signal level to 1.1V to 5V with 100mV steps (like 1.1V, 1.2V, 1.3V.......4.9V, 5V).

Best regards

  • 0
    TI__Mastermind 22810 points

    Hello Ishwar,

    What determines propagation delay:

    Temperature: Increasing the temperature will impact/change electrical properties inside the part. One of these properties is carrier mobility. As temperature increases, carrier mobility will decrease resulting in the signal moving slower through the part. 

    Output Voltage: This part was designed to work best at 5V supplies. The closer we are to 5V, the better performance we will get

    To answer you second question, the supply voltage can be any value between 1.1V and 5.5V. We only listed 1.2V 1.8V, 2.5V, 3.3V and 5.5V because these are the common voltages the industry uses.

    Regards,

    Josh