Figure 19. FPWM output voltage ripple at zero load

6.7

Overcurrent protection

The current protection circuitry features a constant current protection to handle an exceptional dynamic load

request that can persist continuously for maximum 128 clock cycles. Within this time window, the device limits the

DC output current accordingly with valley current threshold programmed value with RILIM resistor, as shown in the

figure below.

Figure 20. RILIM resistor connection to define lossless and precise OCP setting

200 µA

SW

ILIM

RILIM

VIN

internal

internal

SW

ILIM

RILIM

100 µA

VIN

RSENSE

OCP lossless

OCP Precise

In case the overcurrent event is detected longer, the hiccup protection is triggered to limit the stress of the

external power components in case of continuous short-circuit event: the switching activity is prevented for 8192

clock cycles and the SS capacitor is discharged for a new soft-start cycle.

L3751

Overcurrent protection

DS13841 - Rev 1

page 20/41