This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

OMAP L138 Sequencing

Hi,

I am working on a cost sensitive project and would like to know if I can use the following scheme for sequencing of the OMAP L138 and save the cost of the sequencer

 

1. 12V -> Dual Switching regulator -> 1.2V and 3.3V (1.2V power good enables 3.3V rail ensuring 1.2V comes up before 3.3V starts to ramp up)

2. 3.3V -> 1.8V LDO (3.3V and 1.8V start coming up together) 1.8V ldo has a 1.2 uvlo. Tests show that I can ensure the 3.3V rail never exceeds 1.8V rail by 2V.

The datasheet does not mention anywhere that the 1.8V should come up before 3.3V starts to ramp up. My tests show that the 1.8V ldo starts to track 3.3V rail as soon as the 3.3V rail reaches about 1.3V. It does so until the 1.8V rail reaches the 1.8V. The 3.3V continues to ramp up until it reaches 3.3V.

I am not using the usb peripherals only the DDR controller on the 1.8V rail along with the DDR itself

Does anybody think this might be a problem?

 

-Manas