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Increasing internal LDO voltage causes ARM to hang

Question asked by Nori Shinozaki on Sep 9, 2014
Latest reply on Sep 11, 2014 by Nori Shinozaki

Hello Champs,

 

My  customer using i.MX6DL is having trouble of supplying ARM core voltage through internal LDO.

 

They tried a following power scenario.

 

1. LDO 1.150V

・ CPU=396MHz, PMIC-ARMCORE(SW1A/B)=1.3V

・ PMU_REG_CORE-REG0_TARG4–0)= 10010(1.150V, LDO Enable )

 

2. LDO Bypass

・ CPU=396MHz, PMIC-ARMCORE(SW1A/B)=1.3V

・ PMU_REG_CORE-REG0_TARG(4–0)= 11111(-V, LDO Bypass )

 

3. LDO 1.450V

・ CPU=396MHz, PMIC-ARMCORE(SW1A/B)=1.3V

・ PMU_REG_CORE-REG0_TARG(4–0)= 11110(1.450V, LDO Enable )

 

In this scenario, ARM hangs when setting #3.

 

However when they add a following intermediate  power mode between the #2 and #3,

 

2.1. LDO 1.425V

・ CPU=396MHz, PMIC-ARMCORE(SW1A/B)=1.3V

・ PMU_REG_CORE-REG0_TARG(4–0)= 11100(1.425V, LDO Enable )

 

ARM goes fine from #1, #2, #2,1 to #3.

 

Is there any time or some other restriction to increase voltage?

 

Best regards,

Nori Shinozaki

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