LinearRegulatorLinear Regulators: Theory Of Operation and Compensation Linear Regulators: Theory Of Operation and Compensation Introduction The explosive proliferation of battery powered equipment in the past decade has created unique requirements for a voltage regulator that cannot be met by the industry standards like the LM340 or the LM317. These regulators use an NPN Darlington pass transistor (Figure 1), and will be referred to in this document as NPN regulators. The demand for higher performance is being met by the newer low-dropout (LDO) regulators and quasi-LDO regulators. The NPN Regulator The NPN Darlington pass transistor with PNP driver used in an NPN regulator requires that at least 1.5V to 2.5V be maintained from input-to-output for the device to stay in regulation. This minimum voltage ″h……