The device features overcurrent protection with an adjustable protection threshold programmed in the
ILIM_CONFIG_CHx register. Additional programmability is introduced to account for capacitive loads and motor or lamp loads with a high inrush current. The type of load can be specified as capacitive or not using the CAP_CHRG_CHx bits in the
ILIM_CONFIG_CHx register. A value other than 00 indicates capacitive load and the overcurrent protection as well as capacitive load charging behavior is defined for the time defined by the INRUSH_DURATION_CHx bits in the
ILIM_CONFIG_CHx register. In these modes, the current is limited using the cap charging rate that is programmed using the
ILIM_CONFIG_CHx register CAP_CHRG_DVDT [7:4] bits. A CAP_CHRG_CHx setting of 00 is used for a non-capacitive loads and here the overcurrent protection threshold is set using INRUSH_LIMIT_CHx for the time defined by the INRUSH_DURATION_CHx bits. Unlike the capacitive charging modes, the current is not limited but the channel is turned off immediately in case the threshold current is exceeded. In either type of load, the overcurrent protection is immediate turn-off once past the inrush duration phase. The normal load current behavior is shown in the
Figure 8-4 for the capacitive loads and in the
Figure 8-3 for the inductive or resistive loads (like heaters and motors).
An overcurrent protection event occurs when IOUTx exceeds the programmed threshold level, ICL. When IOUT reaches the current limit threshold, ICL, the channel is immediately turned off. Please note that the current may peak at a higher value (ICL_pk) than the programmed overcurrent threshold (ICL). This is due to the limitation of the speed of the over-current protection response.
Figure 8-5 shows the immediate overcurrent protection switch off behavior. The switch will retry after the fault is cleared and tRETRY has expired. When the switch retries after a shutdown event, the fault indication will remain until VOUT has risen to VBB – 1.8 V. Once VOUT has risen, the fault indication at the pin is reset and current sensing is available. If there is a short-to-ground and VOUT is not able to rise, the fault indication will remain indefinitely.