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.

  • Resolved

SN74LVC1G3157: SN74LVC1G3157 ioff function

Prodigy 125 points

Replies: 3

Views: 334

Part Number: SN74LVC1G3157

customer conplain when I/O B is high leven, Vcc will have 1.6V even power down. is it related to ioff protection? SN74LVC1G3157 have no Ioff protectio, the 1.6V is caused by backflow current from I/O? any danger to the device? if I/O A is high, Vcc will also have voltage even power down ?

  • Zhang, 

    The SN74LVC1G3157 doesn't have powered off protection to prevent backflow through the ESD diodes when the Vcc = 0V.

    You will need to select a device like TS5A63157 with powered off protection to prevent this issue.  This device includes a leakage spec when Vcc= 0V.    

    Thank you, 

    Adam

  • In reply to Adam Torma:

    hi adam,
    sorry, VNO/VNC/VCOM's maximum is V+ + 0.5V in TS5A63157 SPEC page.3. one example is V+ is only 0V, VNO/VNC/VCOM can only to be 0.5V? i dont't think so, but could you hlep to explain? thanks!
    another question: I/O range usually is -0.5 ~VCC+0.5V in many SPEC, is it due to I/O's body diode with CMOS technology?
  • In reply to zhang myth:

    Zhang,

    1) The powered off protection specification applies when Vcc = 0 V.  You can see this in the powered off leakage current that when Vcc =0V up to 5.5 V can be placed on COM/NO/NC and <1uA will leak through the switch.

    2) There is typically an ESD protection circuit on the inputs of the signal path that is like a diode to Vcc or GND.  This is why the abs max specifies not to exceed  ~about a diode drop beyond the rails because there will be much exponential leakage current as the voltage increases beyond the supply rails. 

    Thank you, 

    Adam

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.