A 21kHz Phase Boost through Split & Filter Loop Stability Optimisation in Automotive Current Limitation.

In Active Current Limiter for High-Side (HS) circuits adopted in Automotive applications stability is strongly affected by Short Circuit (SC) cases. Such several possible SC cases depend on the specific SC situations occurring in the system and, then, present different electrical conditions, for instance with inductive load from 0 mu H to 20 mu H. These SC events result in large load current step producing large current overshoot, which could damage the overall system. In this paper a simple and extremely efficient solution (namely the Split & Filter (S&F) technique) allows to limit the overshoot during transient response for all the SC events. The technique is applied to a 350nm BCD implementation and experimentally demonstrates that for the most critical cases (i.e. with the lowest Phase-Margin) PM increases from 44 degrees to 57 degrees reducing overshoot from 61% to 30% and decreasing peak current value, from 38.7A to 29.5A, without overcompensating the less inductive short-circuit cases. Technique robustness is validated by extended simulations with PVT corners settings.