iMx6 : VDD_HIGH_IN source

[yannickc]

Dear All,

In most of iMx6 evaluation board VDD_HIGH_IN is supplied by a permanent source that is connected to VDD_SNVS_IN too.

When the PMIC PF0100 is switched off via PWRON input all the power sources are turned off and VDD_SNVS_IN is still powered but the problem is VDD_HIGH_IN is powered too.

Is the LDO that use VDD_HIGH_CAP is still ON ?

I did not see any sequence requirements on VDD_HIGH_IN, so is it possible to disconnect it from VDD_SNVS_IN and connect it to AUX_3V15 (SABRE board) ? of course VDD_SNVS_IN remains connected to the permanent source.

Best regards,

Yannick

[JorgeRama_rezRi · Accepted solution]

Hi Yannick,

Power up sequence is not violated and voltage is within the range, so yes, it is possible. I'd just like to point out a couple of details:

- In this case, VDDHIGH voltage is higher than VSNVS, so there's a rist D10 (NSR0320) is polarized and you could have some leakage there. I checked NSR0320 datasheet and its forward voltage at low currents is 0.24V, so you should be safe there, but please make sure this is not an issue.

- PF0100 SW4 (which supplies AUX_3V15 domain) max current capability is 1A. It is already supplying VGEN1 and VGEN2, which can draw up to 350mA combined. Worst case scenario in app note AN4509 for VDDHIGH is around 70mA, but there may be other circuitry drawing current from this source. Please just make sure your application doesn't exceed the current limit for SW4. I'd recommend to take a few measurements in your board so see how much current it is supplying.

Best regards.
Jorge.

[yannickc]

Hi Jorge,

Thank you for your answer. In fact in my design I will not put a shottcky between VDDHIGH_IN and VDD_SNVS_IN as VDD_SNVS_IN will always be powered externally by the same source that powered the PMIC.

Normally I do not need 1,5V in my own design so VGEN1 and VGEN2 will not be used.

Best regards,

Yannick