design. It is a component in switching regulator designs and is not a linear regulator like other 78xx devices. The 7803SR from Datel is a full switching power supply module (designed as a drop-in replacement for 78xx chips), and not a linear regulator like the 78xx ICs. Advantages While external capacitors are typically required, 78xx series ICs do not require additional components to set their output voltage. 78xx designs are simple in comparison to switch-mode power supply designs. 78xx series ICs have built-in protection against a circuit drawing too much current. They have protection against overheating and short-circuits, making them robust in most applications. Disadvantages The input voltage must always be higher than the output voltage by some minimum amount (typically 2.5 volts). This can make these devices unsuitable for powering some devices from certain types of power sources (for example, powering a circuit that requires 5 volts using 6-volt batteries will not work using a 7805). For input voltages closer to the output voltage, a pin-compatible low-dropout regulator (LDO) can be used instead. As they are based on a linear regulator design, the input current required is always the same as the output current. As the input voltage must always be higher than the output voltage, this means that the total power (voltage multiplied by current) going into the 78xx will be more than the output power provided. The difference is dissipated as heat. This means both that for some applications an adequate heatsink must be provided, and also that a (often substantial) portion of the input power is wasted during the process, rendering them less efficient than some other types of power supplies. When the input voltage is significantly higher than the regulated output voltage (for example, powering a 7805 using a 24 volt power source), this inefficiency can be a significant issue. Buck converters may be preferred over 78xx regulators because they are more efficient and do not require heat sinks, though they might be more expensive. See also DC to DC converter – A class of devices which convert one DC voltage level to another. Linear regulators (and thus 78xx devices) are a form of DC to DC converter. List of linear integrated circuits List of LM-series integrated circuits LM317 – A similar linear regulator chip with a configurable output voltage. References External links Power Supply Design Basics - SGS-Thomson Microelectronics (now ST) Reverse engineering a