L9779WD datasheet(85/170 Pages) STMICROELECTRONICS

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L9779WD

Functional description

169

6.13.4

Diagnosis of CPS [OUT21 to OUT28] when configured as single power

stages

For the low side the diagnosis is the same as LSd.

For the high side the diagnosis is described below.

Each channel locally detects and writes its own fault or no-fault condition (codified on 2 bit

according to Table 28: Fault encoding condition).



Short circuit to battery or overcurrent for all the outputs during ON condition.



Open load or short to GND during OFF condition.

The faults are latched and reset at every Read Diag operation.

In OFF condition the first fault detected is latched and can be overwritten only by the ON

condition fault.

Channel “on”

Short to GND:

Current diagnosis is the result of a comparison between driver load current and internal

Ilimit thresholds.

If:

ILOAD > IOVC for t > TFILTEROVC

the driver is switched off and the fault is set, latched and reset at every Read Diag

operation.

When the fault occurs the driver is switched off with a controlled slew-rate.

The Drivers switches on AGAIN in the following conditions:

–

If command goes inactive and then active again

–

If command remains active driver is switched automatically on at every Read Diag

operation.

Short to VB:

Not available.

Open load:

Not available.

OUT21…28

Tmask_step

Test by scan

-25%

+25%

Tsettle

For information only;

No tested

100

T_PWM

Operating frequency

For information only;

No tested

µs

Table 34. Stepper configuration electrical characteristics (continued)

Symbol

Parameter

Test condition

Min

Typ

Max

Unit

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