i.MX6SL VDD_HIGH_IN voltage.

[satoshishimoda]

Hi community,

I have a question about MCIMX6SLEVK.

Please see the schematics of MCIMX6SLEVK, VDD_HIGH_IN is supplied by MMPF0100 SW2, and VDD_SNVS_IN is supplied by MMPF0100 VSNVS.

These voltage are different (SW2=3.15V, VSNVS=3.0V), so I guessed SW2 output voltage is changed to 3.0V by u-boot same as VGEN5 on SABRE-SD.

However, there is no code to change the SW2 voltage in u-boot for MCIMX6SLEVK.

Is this no problem even though "VDD_HIGH_IN must match the range of voltages that the rechargeable backup battery supports" according Table 9 of IMX6SLCEC Rev.3.

(I understand "rechargeable buckup battery support" = VDD_SNVS_IN)

Best Regards,

Satoshi Shimoda

[art · Accepted solution]

Actually, the VDD_HIGH_IN power rail is connected to the VDD_SNVS_IN power rail through the D24 BAT54 diode that has at leaast 0.25V forward voltage drop. So, in fact, the VDD_SNVS_IN power rail is always powered from the P3V0_VSNVS voltage, supplied from the VIN voltage of the PF0100 PMIC through the internal LDO when the main power is applied, since the difference of the P3V15_VDDHIGH_SW2 and P3V0_VSNVS voltages is less than the minimum diode voltage drop, and is powered by a coin cell through the PF0100 PMIC when the main power is off.

Have a great day,

Artur

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[satoshishimoda]

Hi Artur,

According to your reply, I understood the following note means not "VDD_HIGH_IN should be same voltage as VDD_SNVS_IN", but "VDD_HIGH_IN should be 2.8 ~ 3.3V", right?

Must match the range of voltages that the rechargeable backup battery supports. (Table 9 in IMX6SLCEC Rev.3)

Actually, I thought the above description means "VDD_HIGH_IN should be same voltage as VDD_SNVS_IN", so I guessed SW2 output voltage on MCIMX6SLEVK should be changed to 3.0V by u-boot same as VGEN5 on SABRE-SD.

Best Regards,

Satoshi Shimoda