LP2985: LP2985 Disable issue, Vout is 2.0 when disabled.

Hi Andrew,

Would you be able to share the schematic for this? 

Is Enable connect with Vin or is it a separate connection? What is controlling Enable?

What is the load for this LDO?

Regards,

Andres

ENABLE is controlled by microchip 3.3V dc or 0V.   Load is a G9214-512.  https://www.hamamatsu.com/content/dam/hamamatsu-photonics/sites/documents/99_SALES_LIBRARY/ssd/g9211-256s_etc_kmir1011e.pdf

Vdd is supplied by the LDO. Other I/O were supplied by microchip. 

I think the Vout is either floating or made connection to the Vref inside the LDO. 

Hi Andrew,

Vout has an internal pull-down which should activate whenever the LDO is disabled. Also, the internal Vref is 1.2V, so this may not be the issue since your output is 2V when disabled.

From the datasheet of G9214-512 I don't see why this would cause the output to stay at 2v. 

Do you have a pull-down resistor at the Enable pin of this LDO?

Regards,

Andres

No, I don't have pull-down resistor at the ENABLE. If you have the output pull-down. I am very surprised that I still get 2V.  It should cause over-current is 2V is pulled to ground. 

I don't see your diagram in the pdf . Can you give me the a link. I am looking at this datasheet:

https://www.ti.com/lit/ds/symlink/lp2985-n.pdf?ts=1674003193388

HI Andrew,

I would recommend testing with a pull-down at ENABLE to see if it helps.

If you are using LP2985-N then it does not have an output pull-down, the one I showed was the newer version LP2985 (non-N): https://www.ti.com/lit/ds/symlink/lp2985.pdf

Regards,

Andres

what is the difference between LP2985 and LP2985A ?