Here is the 7805 datasheet which is the popular 5V voltage regulator IC and the 7805 pinout. It is designed to provide a constant 5V at 1.5A max when powered by 7.3V to 35V. We usually use it as a stable voltage source for a common digital circuit. Sometimes, the power supply using a transformer can have too high a voltage. dropout of 1.2 V at 800 mA of load current. The LM1117 is available in an adjustable version, which can set the output voltage from 1.25 V to 13.8 V with only two external resistors. In addition, the device is available in five fixed voltages, 1.8 V, 2.5 V, 3.3 V, and 5 V. The LM1117 offers current limiting and thermal shutdown. It can be expressed using a number of equations, usually all three together, as shown below. V = I × R: R = V: I: I = V: R: Where: V is voltage in Volts R is Notice though that the regulator has to dissipate the excess voltage and can get pretty hot when you draw a fair bit of current. The regulator will fail if the voltage goes over 20V or gets too hot too often; +5V should work fine up to 5V, and I personally wouldn't worry if an external supply delivers up to 5.5V unloaded. Quick recap. If there is 12V power flowing, allow the 5V source to pass through. If there is no 12V source present, flip the switch and shut that 5V source off. (There is always power going threw the 5V source but not always threw the 12V source). Let me know what you guys think would work the best. Giving up 0.5 V on either end is a reasonable compromise between reduction of range (20 % total) and demands on the output structure. For example the AD8676 (a precision amplifier with Rail-to-Rail output) can drive 2 kΩ to ground over the entire temperature range with less than 0.25 V drop, and can sink a couple mA with similar drop. Some op i am currently getting only max. 4.2 V. from the Uno page; 5V. This pin outputs a regulated 5V from the regulator on the board. from the Nano page; The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). \$\begingroup\$ I made an LM317 regulator circuit to provide 4.2 V, however 1. it is a waste of energy 2. it needs a heatsink and can be quite bulky 3. I started to wonder - if the device turns on fine using the 5V provided on the charging port, and it is actually specified to 4.2V, then it might be able to run from 5V as well. Cách Vay Tiền Trên Momo.

can i use 4.5 v instead of 5v