This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SN74CBT3244: Can SN74CBT3244 be used for level shifter for open drain application?

Guru 29690 points
Part Number: SN74CBT3244

Hi Team,

Can SN74CBT3244 be used for level shifter for open drain application by adding pull-up resistors?
I assume 5V to 3.3V purpose.

Best Regards,
Yaita / Japan disty

  • Yaita,

    We recommend signal switches for open drain applications as long as the voltage nodes are the same on both sides of the FET.  Here is an example of a signal switch used in an open drain application like I2C. 

    I would recommend looking at the TXSXXXX or LSFXXXX family of devices for open drain level shifting ICs.  You may also pose a question to the level shifter e2e forum. 

    What is your thought for using a signal switch as a level shifter? 

    Thank you,

    Adam

  • Hi Adam-san,

    Thank you for your comments. I understood.

    >What is your thought for using a signal switch as a level shifter? 
    I believe we can use a signal switch as a level shifter however we need to know which is drain / source of internal Nch-FET A side or B side.
    We should connect source side to 3.3V and drain side to 5V because of internal parasitic diode.

    If anyehere, I will recommend level shifter IC to my customer.
    Thank you.

    Best Regards,
    Yaita

  • Yaita,

    I know you can use an NMOS Nchannel-FET switch for level shifting application but I'm still learning the specifics of this application.  Here is an excerpt from the appnote "CBT-C, CB3T, and CB3Q Signal-Switch Families" that explains how the SN74CB3TXXXX switches can be used for level shifting applications.

    Until I gain more expertise in this application I will defer to level shifter products and their experts for recommendation. 

    Thank you,

    Adam