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
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
