i.mx53 voltage setting for LPDDR2

[KarelH]

Helo, I am currently working on loco board with Linux. There is DDR3 which uses voltage 1,5V.

I would like to create own board based on loco, but with LPDDR2, which uses 1,2V. There is MC34708 pmic and it can be set up for both voltages, but I have problem with finding where this voltage is defind in Linux source code.

Could anyone please help me?

Thank you,

Karel

[JorgeRama_rezRi · Accepted solution]

Hi Karel,

The default voltages of the MC34708 sources are not necessarily defined in Linux code. The MC34708 has 4 pins (PUMS[4:1]) that can be configured to set your desired default voltage configuration. Please see table 11 of the datasheet located in the link below. If you are using SW4 to supply the DDR, then your PUMS[4:1] choice would be 1001 (1 means: tie to VCOREDIG voltage, 0 means: tie to GND). Please check that the rest of the voltages of this option are compliant with your application too. Now, these will be the default power up voltages of the PMIC, but you can change them in your code by writing to the MC34708 registers as soon as you start booting.

Datasheet: http://cache.freescale.com/files/analog/doc/data_sheet/MC34708.pdf?fsrch=1&sr=2

Hope this helps!

Best regards.

Jorge.

[KarelH]

Hi Jorge,

this is exactly what I needed.

Thank you,

Karel