Hi team,
I'd like to confirm the device behavior when the power supply left floating. (Vcc = open)
Could you tell me whether the Vcc isolation feature will work correctly or not.
Regards,
Yoshi
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Hi team,
I'd like to confirm the device behavior when the power supply left floating. (Vcc = open)
Could you tell me whether the Vcc isolation feature will work correctly or not.
Regards,
Yoshi
The VCC isolation feature requires the power supply to be at GND.
When VCC is floating, the voltage is random. So it might be large enough for the device to power up.
To ensure that the outputs are high impedance, connect the OEs to VCC.
Hi Clemens,
Thanks for your quick response.
I'd like to ask one more question.
The customer's schematic some times be a condition that VCCB = 0V, OE is high to ensure the output is Hi-Z. The customer control the VCCB as on and off.
Is there any issue on this case like caused damage, increase power consumption if there is no pull down resistor on input port?
Regards,
Yoshi
This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down.
The VCC isolation feature ensures that if either VCC input is at GND, then both ports are in the high-impedance state.
Thanks for your answer.
I understood the output will disable. How about the input port?
There is no issue when input port is floating. Is it correct?
Please refer to the FAQ on the Vcc isolation.
If you have any further questions, please let me know. I could also update the FAQ if needed.