A new linear regulator features switch mode overcurrent protection [for power supplies]

A linear regulator control circuit for power supply applications is presented which, in addition to offering benefits such as low input-output differential and a precise reference voltage, features a unique and innovative approach to overload protection. By using duty-ratio, switch-mode protection, this circuit eliminates both the high internal dissipation of constant current limiting and the latch-up tendencies of limiting with current foldback. It is argued that while the power supply designer needs to incorporate foldback current limiting to reduce power dissipation, the customer needs constant-current limiting to insure reliable sharing. It is the contention of this work that what they both really need is duty-ratio protection