L6728 datasheet(13/32 Pages) STMICROELECTRONICS

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L6728

Over current protection

13/32

8.1

Over current threshold setting

L6728 allows to easily program a 1st level Over Current Threshold ranging from 50mV to

550mV, simply by adding a resistor (ROCSET) between LGATE and GND. 2

nd level threshold

will be automatically set accordingly.

During a short period of time (about 5ms) following VCC rising over UVLO threshold, an

internal 10µA current (IOCSET) is sourced from LGATE pin, determining a voltage drop

across ROCSET. This voltage drop will be sampled and internally held by the device as 1

level Over Current Threshold. The OC setting procedure overall time length is about 5ms.

Connecting a ROCSET resistor between LGATE and GND, the programmed 1

st level

threshold will be:

the programmed 2nd level threshold will be:

ROCSET values range from 5kΩ to 55kΩ.

In case ROCSET is not connected, the device sets the OCP thresholds to the maximum

values: an internal safety clamp on LGATE is triggered as soon as LGATE voltage reaches

600mV, setting the maximum threshold and suddenly ending OC setting phase.

OCth1

OCSET

⋅

dsON

--------------------------------------------

OCth2

1.5

OCSET

⋅

dsON

--------------------------------------------

⋅

L6728 Datasheet(PDF) 13 Page - STMicroelectronics