MCIMX6ULL_CM Q701 RYU002N05 Mosfet

[maticmohorcic]

I'm checking MCIMX6Y2DVM09AB reference design MCIMX6ULL (SCH-29364_A1) and I do not why why there are two different type of N mosfet used (Q701, Q702) for adding parallel resistors (R707, R708). There are Q701 RYU002N05 and Q702 2SK3018.  PMIC_STBY_REQ drives Q701 drives and GPIO_DVFS drives Q702.

[Yuri]

@maticmohorcic 
Hello,

   i.MX 6ULL Linux supports such features as CPU Frequency Scaling (CPUFREQ),
Dynamic Bus Frequency. Also low power modes can be used. All these features
allow to decrease CPU voltage. 

Regards,
Yuri.

[maticmohorcic]

@Yuri

I undestand that but why different type N mosfet (Q701 RYU002N05 and Q702 2SK3018) are used (in parallel feedback resistor circuit) ?

[Yuri]

@maticmohorcic 
Hello,

     Q702 (2SK3018) has leakage of 1uA (R708 of 1.5M).

https://pdf1.alldatasheet.com/datasheet-pdf/view/173401/ROHM/2SK3018.html

    Q701 (RYU002N05) - leakage of 10 uA (R707, 147K)

https://pdf1.alldatasheet.com/datasheet-pdf/view/429927/ROHM/RYU002N05.html

 Regards,
Yuri

[maticmohorcic]

@Yuri 

Why RYU002N05 is equipped on PMIC_STBY_REQ and it has higher gate-source leakage current (10uA - 2SK3018 has 1uA), so turned on when standy request is enabled.

[Yuri]

@maticmohorcic 
Hello,

  threee working points are available for VDD_ARM_SOC_IN: 1.4V, 1.3V, 0.925V
Look at the comments on the scheme (regarding R1/R2). To get 0.925V - 1.5 Mohm 
is needed as a shunt; for 1.3V - 147 Kohm is enough. 

Regards,
Yuri.