AN4266 datasheet(53/76 Pages) STMICROELECTRONICS

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AN4266

Functional safety requirements for application software

Doc ID 024283 Rev 2

53/76

Figure 16.

Logic scheme of the LVD_FLASH, LVD_GPIO and LVD_VREG

Operation of the LVD_FLASH, LVD_GPIO and LVD_VREG is as follows (software

intervention is not needed):

●

A single LVD (PMU LVD or module LVF) can trigger a fault even if the other LVD is

faulty (this event signals the MC_RGM)

●

During each power on cycle self-test circuitry is able to detect failures on one of the two

LVD’s (this event signals the FCCU).

Mandatory: Core voltage LVD and HVD implement a hardware assisted self-test that needs

to be initiated by software once after the boot.

Note:

Rationale: To check the integrity of the LVD and HVD

Note:

Implementation hint: The hardware assisted self-tests are initiated by configuring

PMUCTRL_CTRL[SILHT[1:0]].

If the self-test passes, an NCF is triggered. If the self-test fails, a PMUCTRL_IRQS flag and

CF are asserted.

Apart from the self-test, the use of the power management unit for ASIL D applications is

transparent to the user, because the operation of the PMU is automatic. The SPC56xL70xx

embeds three LVDs which can detect a failure in the 3.3V power supply. Considering the

failure mode “Wrong Power Regulation”, a diagnostic coverage of 90% is estimated against

both a soft error and DC fault.

3.24

Memory Protection Unit (MPU)

The Memory Protection Unit (MPU) provides hardware access control for all memory

references generated in a device. Using pre-programmed region descriptors that define

memory spaces and their associated access rights, the MPU concurrently monitors all

system bus transactions (including those initiated by the eDMA or FlexRay controller) and

evaluates the appropriateness of each transfer.

Note: This scheme represents only the logical configuration and not the actual silicon

implementation structure.

PMU LVD

module LVD

self-test

circuitry

reference

voltage 2

3.3 V supply

to MC_RGM

(destructive reset)

to FCCU

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