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Retired Product

This is a retired product. There is an updated version available: BOB-12009

Creative Commons images are CC BY-NC-SA 3.0

Description: If you’ve ever tried to connect a 3.3V device to a 5V system, you know what a challenge it can be. The SparkFun logic level converter is a small device that safely steps down either 5V signals to 3.3V or steps up 3.3V to 5V. This level converter also works with 2.8V and 1.8V devices. Each level converter has the capability of converting 4 pins on the high side to 4 pins on the low side with two inputs and two outputs provided for each side.

The level converter is very easy to use. The board needs to be powered from the two voltages sources (high voltage and low voltage) that your system is using. High voltage (5V for example) to the ‘HV’ pin, low voltage (2.8V for example) to ‘LV’, and ground from the system to the ‘GND’ pin.

This revision of the Logic Level Converter fixes the issue with the board not stepping down from 5V to 3.3V correctly.

Dimensions: 0.5x0.6"

Documents:

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Customer Comments

  • Thank you Sparkfun, this was a long time coming. So basically if I desolder R5 and R9 (10K) on my old LLC boards (BOB-8745) and pop in a couple 20K resistors, I’ll basically have this version, correct? And again, thank you.

    • Anyone from sparkfun can confirm that?

    • I would like to know the answer to this as well. I have several of the old boards and would like to be able to use them. Is JerZ right about replacing the 10K with 20K resistors or is there other changes as well with the actual board?

  • I’m using this for SPI with Arduino converting MOSI from 5V to 3.3V. I have a problem with slow response: when input goes from 0 to 5V it takes almost 1 us for the output to reach 2V, and so it is unusable at full SPI speed on the Arduino. With a clock divider of 32 it just about works, but the waves are all triangular.

    Is this to be expected?

    I’ve connected: LV to 3.3V, HV to 5V, RXI to Arduino output and RXO to oscilloscope, and all GND to ground of course. I’ve tried to connect RXO to the SPI slave chip as well, but it looks the same.

    Update: tried with 5V input on TXI and 3.3V output on TXO. This is much faster, usable with no clock divider.

  • When are you making more of these, the newer version does not work for my application.

  • This should be simple, but i cannot get my 11978 board to convert 3 volts to 5. I have connected the 5v to HV, and 3 volts to LV with a common ground to both. Supplied a 3 volt signal to TXI and TXO remains at 5v even when i remove the 3v input toTXI. Am i missing something?

  • Hi I would like to ask if any one of you guys has tried this logic converter with a signal whose frequency is in the order o 2 Mhz up to 8 Mhz? I have read the schematic and they are using BSS138 which is CMOS device (very fast device, gate on-off is in order of nano seconds) but I would like to hear it from some one who had a practical experience with it in high frequencies.

    Regards. OAH

    • It was simple. My reference was wrong. Great Product.

    • I would also like to know if anyone else has tried this. Giving the device a 2Mhz frequency square wave my signal was taking about 2 microsec to get from 3.3 to 5V. LV was 3.3V, HV was 5V. But I would like to know if anyone else has seen this.

  • can this be used to interface between a 5V arduino pro and an sd card socket?

  • only boards or components also?

    • Components, pre-soldered to the boards, also. It comes as you see in the pictures (minus the shiny quarter).

  • so I can use this as an RS232 level shifter correct? as long as I use 12v on the hight side and 1.8/2.8/3.3/5 volts on the low side?

    • No, RS-232 is bipolar, with both negative and positive levels with respect to ground to encode different states of the RS-232 data. The logic levels are unipolar, with positive voltages near 5/3.3/etc. volts for “1” and near zero volts to encode a “0” level.

  • So a digital one going into the TXO pin on the 5V side will show down on the TXI pin on the 3.3V side as 3.3V!!!

  • Sweet, however I’m a bit sad I have a few old ones lying around. I’ll save them for the rare case when I need to step up 3.3 to 5 I guess.

  • Pins are labeled as Inputs and Outputs. These are relative to the board. A digital one going into the RXI pin on the 5V side will show up on the RXO pin on the 3.3V side as 3.3V. A digital one going into the TXI pin on the 3.3V side will show up on the TXO pin on the 5V side as 5V.

  • This worked great for me, thanks!

  • What is the purpose of the two “micro-fiducials” on this board? Do they aid the optical alignment of your pick and place machines?

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