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LM7812Series Voltage RegulatorsGeneral DescripTIonThe LM7812series of three terminal regulators is availablewith several fixed output voltages making them useful in awide range of applicaTIons. One of these is local on cardregulaTIon, eliminaTIng the distribution problems associatedwith single point regulation. The voltages available allowthese regulators to be used in logic systems, instrumentation,HiFi, and other solid state electronic equipment. Althoughdesigned primarily as fixed voltage regulators thesedevices can be used with external components to obtain adjustablevoltages and currents.The LM78XX series is available in an aluminum TO-3 packagewhich will allow over 1.0A load current if adequate heatsinking is provided. Current limiting is included to limit thepeak output current to a safe value. Safe area protection forthe output transistor is provided to limit internal power dissipation.If internal power dissipation becomes too high for theheat sinking provided, the thermal shutdown circuit takesover preventing the IC from overheating.Considerable effort was expanded to make the LM78XX seriesof regulators easy to use and minimize the number ofexternal components. It is not necessary to bypass the output,although this does improve transient response. Input bypassingis needed only if the regulator is located far from thefilter capacitor of the power supply.For output voltage other than 5V, 12V and 15V the LM117series provides an output voltage range from 1.2V to 57V.
