P2020 device status/behavior if VDD falls below lower limit due to ripple I would like to know about status/behavior of P2020 processor in case VDD falls below lower limit voltage due to ripple etc. According to Table 3. Recommended Operating Conditions in P2020 Hardware Spec (Doc#: P2020EC), the recommended value for VDD, AVDD_xxxx, SVDD_SRDS and XVDD_SRDS is “1.05 ± 50 mV”. It means that the lower limit voltage is 1.00 V. Could you please let me know about possible P2020 device status/behavior if the lower limit of the ripple voltage falls below the specified minimum voltage of 1.00V ? (For instance, center voltage of VDD = 1.01V, but the lower side of the ripple voltage goes 0.99V (below 1.00V)) Is there no problem for proper operation of the device if center voltage of VDD keeps higher or equal to 1.00V ? Will there be any operation/damage risks even with ripple voltage ? Please advise. Thank you in advance. Re: P2020 device status/behavior if VDD falls below lower limit due to ripple Hello,
The P2020 Hardware Spec (Doc#: P2020EC) Table 3 specifies VDD, AVDD_xxxx, SVDD_SRDS, and XVDD_SRDS as 1.05 ± 50 mV, meaning the valid operating range is 1.00 V (min) to 1.10 V (max). This is a Recommended Operating Condition, not an Absolute Maximum Rating.
The critical point is: the specified minimum voltage of 1.00 V applies to the instantaneous voltage at the device pins — not just the DC center point. Ripple is part of the actual voltage the device sees, and the device is tested and characterized only within the specified range.
Risks When Ripple Dips Below 1.00 V
Even if the center (DC) voltage is at or above 1.00 V, allowing the ripple trough to fall below 1.00 V constitutes operation outside the Recommended Operating Conditions. NXP's position on this, consistent across QorIQ and related processor families, is:
Functional/Operational Risk: When VDD momentarily drops below the minimum, the processor's internal logic may not have sufficient drive strength or timing margin to operate correctly. This can manifest as:
Incorrect instruction execution
Data corruption (e.g., memory miscompare errors)
Unpredictable behavior in critical timing paths
A directly analogous NXP case involving a related QorIQ processor (P1013) confirmed: "There is a potential risk of functional issues when running [the device] at [a voltage near the limit], as this value represents the customer's configured set point. Normal voltage tolerance, ripple, or transient behavior could result in the voltage exceeding [or falling below] this level."
The "Center Voltage ≥ 1.00 V" Argument Is Not Sufficient: The device does not "average" the supply voltage. Digital logic operates on instantaneous voltage. During the ripple trough (e.g., 0.99 V in your example), the device is genuinely operating below spec, even if only for a fraction of a switching cycle. This can cause setup/hold time violations in internal flip-flops, leading to functional errors.
No Permanent Damage Expected for Small, Brief Excursions: For a small ripple excursion (e.g., 10 mV below the minimum, at typical switching frequencies), permanent physical damage to the device is unlikely — the voltage is still well above the absolute maximum ratings floor. However, functional correctness is not guaranteed, and NXP does not support or characterize operation in this condition.
Reliability/Longevity: For the P2020 specifically, operating at the lower edge of the voltage range (rather than above it) is generally less of a long-term reliability concern than operating above the maximum. However, repeated or sustained operation outside spec is neither recommended nor supported.
NXP's standard guidance, confirmed across multiple QorIQ and related processor support cases, is:
"Operating devices outside of specification is neither recommended nor supported."
The entire voltage waveform — including ripple — must remain within the specified 1.00 V to 1.10 V window at the device pins during normal operation.
Regards
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