I am trying to connect two devices on a PCB. One operates with 3.3V digital high and the other works with 5V digital high. I actually grouped the input and output pins (There is no bidirectional pins). The ports have minimal current levels like 10mA. However, the speed of the channels are very important. I totally have 60 pins and try to build a small PCB. Do you recommend any logic level shifter for my work?

P.S: I saw lots of level shifters but my aim is to find the most basic one with the highest channel capacity. I seek a solution from your previous experiences.

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    \$\begingroup\$ You should look at the input & output voltage level specs of your devices and compare them. You may find in many cases that you can drive 5V inputs with 3.3V outputs \$\endgroup\$
    – brhans
    Jun 9, 2015 at 12:19
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    \$\begingroup\$ A 3V3 logic output is likely compatible with a 5V logic input. \$\endgroup\$
    – Andy aka
    Jun 9, 2015 at 12:20
  • \$\begingroup\$ ^this. And it might happen that a 3V3 input tolerates voltages up to 5V. What andy says is very likely to be true while what I am saying must be checked on the datasheet. \$\endgroup\$ Jun 9, 2015 at 12:22
  • \$\begingroup\$ I couldn`t find any expression about the threshold on the datasheet. Edit: Sorry, I found it now. The digital input module is in 4V to 50V input voltage range \$\endgroup\$ Jun 9, 2015 at 12:30
  • \$\begingroup\$ 4 to 50V input voltage range... On a digital input pin??? really? Care to give a link? \$\endgroup\$
    – jwsc
    Jun 9, 2015 at 12:35

1 Answer 1


the most basic one would be a few resistors. As always, google is yor friend. Here a thing that I found.

If you go for a resistor divider, speed will be reverse proportional with the flowing current. So If you have some energy saving considerations to make, it will not be too fast. Of course, speed is relative. In my 8-bit designs, 1MHz is ridicolously fast. In a Media Application, I would rather have something like 300MHz.

EDIT: You ask specifically about integrated level shifters, do you? I misread your question. A good way to find something for your needs would be to search a big distributor like Farnell/DigiKey or Mouser. They have parametric search engines where you can search for number of channels and price. With this you would find the most basic(read cheap) for a given number of channels.


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