National Semiconductor LM78LXX Manuals

LM78LXX Series Three Terminal Positive Regulators

The LM78LXX series is a three-terminal positive regulator with several fixed output voltages, making them suitable for a wide range of applications. When used as a zener diode/resistor combination replacement, the LM78LXX usually results in a significant improvement in effective output impedance and lower quiescent current. These regulators can provide on-card regulation, eliminating the distribution problems associated with single point regulation. The available voltages allow the LM78LXX to be used in logic systems, instrumentation, HiFi, and other solid-state electronic equipment. The LM78LXX is available in plastic TO-92 (Z) package, plastic SO-8 (M) package, and a chip-sized package (8-Bump micro SMD) using National's micro SMD package technology. With sufficient heat sinking, the regulator can deliver an output current of 100mA. Current limiting is included to limit the peak output current to a safe value. Safe area protection is provided for the output transistors to limit internal power dissipation. If the internal power dissipation exceeds the heat sinking capability, the thermal shutdown circuit prevents the IC from overheating.