A very simple micro power 5 volts DC regulator can be designed using few operational amplifiers and some other electronic parts .
This 5 volt regulator is ideal for instrumentation requiring good power efficiency . Maximum load current is 10 mA , and can be increased by changing Q1 to a power transistor and proportionally increasing the set current of A2 .
This circuit accepts a wide input voltage range between 6.5 volt and 30 volts .
Low power 3 terminal IC regulators typically draw 2mA to 5mA quiescent current compared to only 50uA with this discrete implementation .
Using the LM5119 dual synchronous buck controller intended for step-down regulator applications from a high voltage or widely varying input supply can be designed a very simple and high efficiency power supply circuit .
The control method is based upon current mode control utilizing an emulated current ramp.
Current mode control provides inherent line feed-forward, cycle- by-cycle current limiting and ease of loop compensation.