LT3045 start-up problems

We are using the LT3045 in several rather simple designs with dual supply, such as: 

https://github.com/TU-Darmstadt-APQ/RedPitaya-Lockbox


You can find a snap shot of the power supply section below.
In all designs we are experiencing the same start-up problem:

Whenever the negative rail comes up first, the LT3045 will not turn on. If the positive rail comes up first, the LDO works as expected.

Has this problem occured to someone else? Can anyone recommend a solution that does not require a large overhead (e.g. power sequencing)?


Parents
  • I redrew your circuit to include the load behavior for the two possible scenarios in the image below.  The Abs. Max. rating of the LT3045 is violated when the negative LDO starts first unless the LT3045 OUT is clamped to ground as I show in the image.  That's why the LT3045 does not start up for that scenario.  Start up is fine if the positive LDO starts first. 

    LT3045 LT3094_2.png

Reply
  • I redrew your circuit to include the load behavior for the two possible scenarios in the image below.  The Abs. Max. rating of the LT3045 is violated when the negative LDO starts first unless the LT3045 OUT is clamped to ground as I show in the image.  That's why the LT3045 does not start up for that scenario.  Start up is fine if the positive LDO starts first. 

    LT3045 LT3094_2.png

Children