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

K.Yaita
Guru 29710 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

  • 0
    TI__Mastermind 45455 points

    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

  • 0 in reply to Adam Torma
    Guru 29710 points

    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

  • 0 in reply to K.Yaita
    TI__Mastermind 45455 points

    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