AN4266 datasheet(52/76 Pages) STMICROELECTRONICS

52 / 76 page

Functional safety requirements for application software

AN4266

52/76

Doc ID 024283 Rev 2

Since power is critical to the operation of the SPC56xL70xx there is built-in redundancy to

the PMU core LVDs and HVDs. LVD_DIG_MAIN and HVD_DIG_MAIN monitor the digital

core voltage and have backups for additional safety protection (LVD_DIG_BKUP and

HVD_DIG_BKUP). Internal architecture allows for testing of the functionality of the main and

back up LVD_DIG and HVD_DIG, as well as trimming circuitries (See Figure 15). The

PMUCTRL module provides software initialized BISTs which test the digital core supply

HVD and LVD (both main and backup).

Figure 15.

Logic scheme of the LVD_DIG and HVD_DIG

If the self-test circuitry detects a fault in the main or backup detectors the reaction will be

one of the following (See “Built In Self-test (BIST)” subsection of the “Power Management

Unit (PMU)” section in the SPC56xL70xx Reference Manual):

●

Critical Fault (CF[21]) triggered and one or more of the following:

–

Main Low Voltage Detector Pending – PMUCTRL_IRQS[MLVDP] = 1

–

Backup Low Voltage Detector Pending – PMUCTRL_IRQS[BLVDP] = 1

–

Main High Voltage Detector Pending – PMUCTRL_IRQS[MHVDP] = 1

–

Backup High Voltage Detector Pending – PMUCTRL_IRQS[BHVDP] = 1

●

Destructive reset triggered

If the self-test circuitry detects a fault in the main or backup detectors the FCCU will read a

CF.

There are dedicated LVD’s in the flash memory, I/O and VREG providing additional

redundancy. This solution is different from the 1.2 V digital core supply monitoring, but still

provides the same level of safety coverage. The outputs of the first and the second LVD are

logically AND’d in such a way that a single LVD can trigger a fault, even if the other LVD is

not functioning properly (See Figure 16).

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

implementation structure.

HVD_DIG_MAIN/

self-test

circuitry

reference

voltage 2

to FCCU

to MC_RGM

(destructive reset)

to MC_RGM

digital supply

(1.2V)

reference

voltage 1

LVD_DIG_MAIN

HVD_DIG_BKUP/

LVD_DIG_BKUP

AN4266 Datasheet(PDF) 52 Page - STMicroelectronics

AN4266 Datasheet(HTML) 52 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

Datasheet Download

Link URL