• TI thinks resolved

SN74LVC1G3157: Can I/O signal voltage be greater than supply voltage? (SN74LVC1G3157)

Part Number: SN74LVC1G3157

Hi, 

For the device SN74LVC1G3157, can B1/B2 (I/O signals) have a higher voltage level than Vcc (supply voltage)? 

Is it true that if B1 or B2 are higher than Vcc, the NMOS will not open properly but the PMOS will still work normally? Therefore, a higher (than Vcc) B1/B2 voltage can be transmitted. 

Are there any other concerns for safety or accuracy? 

Thank you, 

  • Whitney,

     

    Yes the SN74LVC1G3157 is a NMOS in parallel with PMOS FET switch.  This switch architectures is sometimes called bilateral switch or transmission gate.  You are correct the advantage of this switch is being able to support a wider voltage range than using a single NMOS or PMOS switch.  However if you look in the datasheet there are more limitations due to transistor stress limitations and ESD protection structures inside the IC. 

     


     

    What type of signals are you trying to switch and what supply voltage do you want? 

     

    The SN74CB3Q3257 for example includes a NFET with its gate tied to a charge pump.  This device can pass signals greater than Vcc on its signal path.



     

    Thank you,

    Adam