ADM7151 doesn't turned off totaly. Why?

Hi,

I'm using the ADM7151ACPZ-04-R2 regulators, in several places, in my board.

One of the regulators is designed to generate 5V_VCC, from 6V input.

When EN is high level (3.3V), regulator produces normal output, of about 4.9V.

When EN is low level (0V), regulator doesn't turn off output to 0V. I measure about 1V.

During the debug of this problem, I found three mistakes, in my design.

I corrected the three mistakes, but still regulator is not totally off, when EN is at low level.

See below a copy, of the relevant portion in my design. The corrected mistakes are colored Red.

I have similar problem with 3.3V regulator, which is designed using ADP125ACPZ-R7.

VOUT is 3.26V when EN is 3.3V and it reduced to 1.8V, when EN is 0V.

All other regulators seems to be okay on enabled and disabled states.

Parents
  • 0
    •  Analog Employees 
    on Sep 4, 2014 8:52 PM

      The ADM7151 is connected correctly and you say you have a similar
    issue with the ADP125.  I am thinking that there is another power source
    that is pulling up the LDO outputs via the protection diodes or some other
    leakage path in the loads.  We need to see a more complete schematic with
    the loads and any other supplies.

Reply
  • 0
    •  Analog Employees 
    on Sep 4, 2014 8:52 PM

      The ADM7151 is connected correctly and you say you have a similar
    issue with the ADP125.  I am thinking that there is another power source
    that is pulling up the LDO outputs via the protection diodes or some other
    leakage path in the loads.  We need to see a more complete schematic with
    the loads and any other supplies.

Children
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