Protections

AN4355

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DocID025240 Rev 2

5

Protections

The L648x devices provide a complete set of protections designed to prevent damaging the

device in critical conditions.

The implemented protections are:



Overtemperature (see Section 5.1)



Overcurrent (see Section 5.2)



Gate drivers undervoltage (see Section 5.3)



5.1

Overtemperature protection

The overtemperature protection disables the power stage of the device when the

temperature of the chip exceeds the safe operation conditions.

The device provides a 3-levels protection: when the temperature exceeds the warning

threshold an alarm condition is set, but the device operation is still guarantee. If the

temperature further increase, the output shutdown threshold is triggered and the gate

drivers are disabled. The device is kept in this condition until the junction temperature

decreases below the release threshold. A second protection is triggered if the device

temperature continues increasing even when the gate drivers are disabled. This protection

turns off the internal voltage regulators and it is released only when the device temperature

falls below the warning threshold.

5.2

Overcurrent protection

The overcurrent protection monitors the drain-source voltage drop of all the external power

MOSFETs and disables the power stage when the programmed threshold is reached. No

information about the specific MOSFET or bridge causing the failure is available.

As soon as the overcurrent protection is triggered the device is locked in a safe condition (all

MOSFETS are turned off) and is kept in this condition until the OCD failure flag is released

by a GetStatus command (see the Section 6.9 in the L6480 and L6482 datasheet for

details).

When the device is locked in safe state no commands which enable the bridges can be

executed (e.g.: Move, Run, GoTo, HardStop, etc.). The commands are simply ignored, no

non-performable signaling is returned by the device.

Warning:

The overcurrent protection can be disabled setting the

OC_SD pin of the CONFIG register to zero. However it is not

recommended to disable this protection.