2337656_en-US

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S32K388 V11 Regulation Accuracy

Hello NXP team,

S32K388 datasheet indicates nominal V11 regulation of 1.14V. The datasheet does not specify the expected range (minimum to maximum) of V11 regulator.

What is the minimum and maximum regulation range/accuracy of S32K388 V11 regulator with external NMOS over the range of possible loading, temperature, and manufacturing variation?

Thank you

Re: S32K388 V11 Regulation Accuracy

Hi@PI

The S32K388 datasheet does not specify any minimum or maximum regulation accuracy or regulation range for the V11 regulator with external NMOS over load, temperature, or manufacturing variation. The only published value is a typical V11 output of 1.14 V, with no tolerance window provided.

V11 is the core and logic supply. It is driven by the external NFET which is controlled by a linear regulator inside PMC.

The voltage of V11 is dynamically adjusted and is affected by factors such as NMOS, gate stabilization capacitor, and power consumption in core operating mode. Therefore, I think this is why a tolerance range is not provided.

Re: S32K388 V11 Regulation Accuracy

Hello Sanlent,

There should be a reasonable range given the datasheet specifies recommended specification limits for external NMOS selection.

It is understood that V11 is regulated by the MCU itself. For testing purposes, it is necessary to know the possible range of V11 voltage regulation. Can you provide this expected range, accounting for manufacturing variation and temperature variation?

How much can this V11 voltage dynamically adjust?

Re: S32K388 V11 Regulation Accuracy

Hi@PI

Similar questions have been asked before, and I have copied the design team's response below.

"I understand that customer may to insist on this topic, but the limits value are not provided for V11, due the V11 is the reference voltage for the CORE, the custumer dont provides +1.1V, the customer just provides +1.5V, and this is the voltage must assure and select an appropiate NMOS based on their application.

"

Re: S32K388 V11 Regulation Accuracy

Hello 

Regarding dynamic behavior, V11 is adjusted internally as required for device operation, but it is not specified as a regulated output in terms of external accuracy or transient performance.

The device includes internal monitoring mechanisms such as Low Voltage Reset (LVR), which supervise the core supply condition. As a reference, the internal LVR deassert level is typically in the range of approximately 1.067 V to 1.107 V (sensed on-chip). This internal condition defines whether the device can operate correctly.

From a system design perspective, the focus should be on proper implementation of the external NMOS control loop. This includes selecting a MOSFET with appropriate threshold characteristics and conduction capability, as well as ensuring stable loop behavior with the required external components (such as the stability capacitor).

In addition, the layout is critical. The NMOS and associated components should be placed as close as possible to the MCU, with a low-impedance connection to the internal supply nodes. The power path between the external supply (e.g., V15) and the internal node (V11) must be supported by solid plane implementation and proper referencing.

It is important to ensure that the V11 and V15 connections are backed by continuous planes with sufficient stitching vias when transitioning between layers. These stitching vias are required to avoid current constriction, reduce parasitic inductance, and maintain low impedance along the current path.

Achieving low impedance (target impedance) in this path is key to minimizing voltage drop and ensuring consistent behavior under load.

Best regards

Re: S32K388 V11 Regulation Accuracy

Hello,

As discussed in PDT last week, can we receive a better/tighter voltage regulation range? The one provided has a wide range.