LM3881: EN signal before powering up

xiaoguang.zhu

Part Number: LM3881

The recommended behavior is to assert EN after powering the VCC. I'd like to confirm that if EN rise up to 0.55V without powering VCC, is there any problem?

Thanks.

6 months ago

0 Dhanyasree Prem Sankar 6 months ago

TI__Expert 4260 points

Hi Xiaoguang,

Kindly refer to the thread that has a similar query and has been answered by our team.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1062049/lm3881-abnormal-operation-assert-en-before-vcc

If you still have any more questions or the answer is not clear, let me know.

Thank you,

Dhanya Prem

0 xiaoguang.zhu 5 months ago in reply to Dhanyasree Prem Sankar

Prodigy 30 points

Hi Dhanya,

Thanks for your answer.

The voltage 0.55V doesn't reach EN pin threshold, does this still matter when it come before VCC?

Thanks.

0 Dhanyasree Prem Sankar 5 months ago in reply to xiaoguang.zhu

TI__Expert 4260 points

Hi Xiaoguang,

I believe if EN is applied before VCC voltage reaches its minimum operating voltage, it could cause some unpredicted behavior. There is an ESD diode inside the chip, so when EN is applied without VCC, the ESD diode is activated causing a leakage path.

Thank you,

Dhanya Prem

Power management

Power management forum

LM3881: EN signal before powering up