• TI Thinks Resolved

CD74HC4067: Looking for an i2c or SPI 16 or > TTL Driver, 100mA

Prodigy 45 points

Replies: 3

Views: 55

Part Number: CD74HC4067

Hello, I'm hunting for a TTL driver that can source 100mA maximum current @ 5V, which is i2C or SPI controlled, ideally capable of 3.3V or 5V control side logic. 
Does TI carry a product like this? I've been hunting quite a bit but it seems the current requirement places my device more on the LED driver side than on the logic side. 

The main reason for wanting 100mA is to adequately source high impedance devices, e.g. 50 Ohm inputs. Apologies if this isn't the best subforum for this question!


  • Hi Austin,

    Looks like you need a buffer/driver not a multiplexer for your application.

    The logic team can recommend the best part for your application but you can look at this link to see what is available.

    Hi Logic team.

    Can you help Austin with a TTL driver?



  • 50 Ω is a low impedance.

    It is impossible to get 100 mA at exactly 5 V from a 5 V supply because there are no logic devices with an output impedance of exactly 0 Ω. How much voltage drop can you afford?

    Do you actually want to drive a 50 Ω load or a 50 Ω transmission line? Because in the latter case, you would want to use a driver with a matching impedance, and the resulting current would be 50 mA. See [FAQ] What happens when I connect a logic device's output to a 50 ohm transmission line?

  • In reply to Clemens Ladisch:

    Hi Austin,

    You will not require a 100mA drive strength device. You mentioned you are sourcing high impedance devices? These devices will not require a high current drive. And as clemens mentioned, if you are looking for a 50 ohm transmission line, then this is not the same thing as a 50 ohm load. The 50 ohms is just the characteristic impedance of the transmission line, meaning the V/I at any point on the transmission line will equal 50. You can just use any of our high drive LVC buffers with damping resistors to get the best results.