The AMS2942 are micropower voltage regulators ideally suited for use with high voltage powered systems. This device feature very low quiescent current (typ.130A), and very low dropout voltage (typ.45mV at light loads and 380mV at 100mA). The quiescent current increases only slightly in dropout. The AMS2942 has positive transient protection up to 60V and can survive unregulated input transient up to 20V below ground. AMS2942 is designed with a tight initial voltage reference tolerance, excellent load and line regulation (typ. 0.05%), and a very low output voltage temperature coefficient, making these devices useful as a low-power voltage regulator in telephone applications, using the telephone line as a power source. The AMS2942 is available in a special 8-pin plastic SOIC in which pin 2 and 3 are fused together with the package paddle serving also as heat sink. An error flag output warns of a low output voltage, often due to failing voltage on input line. A logic-compatible shutdown input is available, which enables the regulator to be switched on and off. The output voltage can be programmed from 1.23V to 42V with an external pair of resistors.