08-09-2017, 11:27 AM
The LM78XX series of three terminal controllers is available with several fixed output voltages, making them useful in a wide range of applications. One of these is the local regulation of cards, eliminating the distribution problems associated with single point regulation. Available voltages allow these controllers to be used in logic systems, instrumentation, HiFi, and other solid state electronics. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents. The LM78XX series is available in an aluminum TO-3 package that will allow a charging current of more than 1.0A if adequate heat cooling is provided. Current limitation is included to limit the maximum output current to a safe value. Safe area protection is provided for the output transistor to limit internal power dissipation. If the internal power dissipation becomes too high for the provided heat sinking, the thermal shutdown circuit is in charge of avoiding overheating of the IC. Considerable effort has been extended to make the LM78XX series of controllers easy to use and minimize the number of external components. It is not necessary to skip the output, although this improves the transient response. Input diversion is only necessary if the regulator is located away from the filter capacitor of the power supply.