Latest spec for i.MX8QM has VDD_MEMC Maximum Supply Currents (Table 10) increased from 2.5A (supported by PF8x00 BUCK5) to 3.2A.
What is the recommendation to provide this extra current?
If after testing, modification of the accuracy and efficiency information is required, modification of the documentation would be done in the datasheet revision 9.0 accordingly to the change of 2.5A to 3.2A, but only if needed, unfortunately we do not know yet if it will be modified. Most likely, the SWxACC will remain at +/- 2% even for 3.2A.
I have check with the PMIC product engineers and they let me know that they are tightening the spec of SW5 to ensure the Current limit can support the 3.2A in the MEMC, this is the write up from the MCU team.
In coordination with the 8100/8200 PMIC family, the i.MX8 MEMC increase to 3.2A will be supplied by the PMIC SW5 peak current limit increasing from 3.6A to 3.9A. This is in respect to the peak current on the inductor of 3.9A.
SW5 will reflect a max 2.5A nominal current, but the platform will still be able to operate in noted specifications of 3.2A max current, but can supply peak current up to 3.9A.
It is important for customers to set the SW5_ILIM[1:0] = 11 to select the maximum current limit on this block. Since the 3.9A current limit in the SW5 regulator is with respect to the INDUCTOR PEAK CURRENT.
The max current required by the i.MX 8 (3.2A) is ensured by the maximum DC current supplied by the SW5 before entering current limitation.
ILIM – (IRIPPLE/2) ≈ 3.9A-(0.5A/2) = 3.65A
A Customer Information Notification (CIN) will be published by the PMIC team to reflect the change in the datasheet rev 9.0 with SW5 from 3.6A to 3.9A peak current limit.
Thank you for following up on this, I think it is fairly clear.
To confirm, the PMIC specification for items like DC accuracy and efficiency will remain at 2.5A? For example VSWxACC? PMIC won't specify the accuracy of regulator between 2.5A and 3.2A?
If so, I will follow up with processor team whether they are going to loosen the specification for cases >2.5A since it will not be possible to guarantee staying between 1.05 V and 1.15 V with no accuracy specification of PMIC.
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