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ATA5279/ATA5279C [DATASHEET]

9125P–RKE–05/14

Figure 3-6. Example 2, Using the Diagnosis Mode

If channel four is activated in normal operation, a fault shutdown will occur. The reason for this shutdown (i.e., the entry in the

fault register) could either be an overload on the A4P line (here a short circuit to VS) or a short-circuit on the A4N line to VS.

In any case, the IC protects itself and the external components from damage; however, the fact that there is more than one

failure in the wiring cannot be discovered.

In diagnosis mode, by testing the A4P line with S_H4P and S_L4P, the short circuit to VS could be found first. The same

result would be found when testing the return line switch 4 accordingly, so the presence of more than one fault on coil 4 is

determined. The precise fault cannot be found though. The diagnosis result would be the same both for the above shown

combination of the two.

Again, this is only an example of how the diagnosis system can be used. Generally, a more systematic approach is

suggested in order to efficiently test all connection lines used.

Note:

To exit the diagnosis mode correctly, two SPI commands have to be sent: the first is the Select Driver com-

mand with the DM bit set to 0 and the second is a Reset Fault Status command. See also SPI Command

Description.

Table 3-3.

Sequence for Example 2, Using the Diagnosis Mode

Step

Command

I/O

Coding

Actions / Remarks

1

Select Driver

I

00101101 – 2Dh

Selects driver 4 with Diagnosis Mode enabled

2

Get Driver Setup

I

O

01101000 – 68h

00011101 – 15h

Reads back active driver info:

Channel 4 active, A4N returns a 1

3

Set Coil Current

I

10100010 – A2h

Closes test switches S_L4P and S_H4N

Note:

S_H4P and S_L4N are open then

4

- no command -

Wait for the test structures to stabilize in the new

setting, see first example

5

Get Driver Setup

I

O

01101000 – 68h

00011101 – 1Dh

Reads back active driver info:

Channel 4 active, both lines return a 1

6

Set Coil Current

I

10100000 – A0h

Closes test switches S_L4P and S_L4N

Note:

S_H4P and S_H4N are open then

7

- no command -

Wait for the test structures to stabilize in the new

setting, see first example

8

Get Driver Setup

I

O

01101000 – 68h

00010101 – 15h

Reads back active driver info:

Channel 4 active and A4N returns a 1

A4N

A4P

VDS

GND

S_L4N

S_H4N

S_L4P

S_H4P

Status_4N

Status_4