SNVSCM6 February 2024 LMR38015
PRODUCTION DATA
The integrated soft-start circuit prevents input inrush current impacting the LMR38015 and the input power supply. Soft start is achieved by slowly ramping up the target regulation voltage when the device is first enabled or powered up. The typical soft-start time is 4.2ms.
The LMR38015 also employs overcurrent protection blanking time, TOCP_BLK (18ms typical), at the beginning of power up. Without this feature, in applications with a large amount of output capacitors and high VOUT, the inrush current is large enough to trigger current-limit protection, which can make the device enter into hiccup mode. The device tries to restart after the hiccup period, then hits the current limit and enters into hiccup mode again, so VOUT cannot ramp up to the setting voltage ever. By introducing the OCP blanking feature, the hiccup protection function is disabled during TOCP_BLK, and LMR38015 charges the VOUT with the maximum limited current, which maximizes the output current capacity during this period. Note that the peak current limit (IHS_LIMIT) and valley current limit (ILS_LIMIT) protection functions are still available during TOCP_BLK, so there is no concern of inductor current running away.