L9945 datasheet(115/144 Pages) STMICROELECTRONICS

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Table 36. Diagnostic codes

Channel Status

diag_xx[2-0]

Priority

OC pin failure (see note below)

000

OC failure

001

STG/STB failure

010

OL failure

011

No failure

100

No OC failure

101

No OL/STG/STB failure

110

No diagnostic done

111

Note:

The OC pin failure, corresponding to the code "000" is available only for channels operating in Peak & Hold. This

code is unused in other configurations. Refer to Section 5.6.2 in order to understand how this diagnostic is

performed.

Figure 28. Diagnostic codes quick look

GADG0806171512PS

For an immediate fault detection, the MSB of the diagnostic code can be evaluated, as shown in Figure 28. An

MSB equal to zero indicates that a failure occurred.

By default, all channels will report the "No diagnostic done" message. Such message is also reported in case

diagnostic has been disabled. The diagnostic status follows a priority concept: if more than one event occurs on a

channel, only the one with the highest priority will be encoded in the diag_xx[2-0] bit. Priority codes are related to

the severity of the fault. OC failures have the highest priority.

The diagnostic latches are reset in case of SPI readout, POR or NRES. After a reset event, diagnostic filters are

reset to prevent false detection.

Figure 29 shows an equivalent Finite State Machine (FSM) that helps understanding diagnostic priority.

L9945

Safety & diagnostics

DS12275 - Rev 10

page 115/144

L9945 Datasheet(PDF) 115 Page - STMicroelectronics