The formula for the output voltage of the 12v to 5v converter using LM317 is written above. It gives approximate value “Vo” when R2 and R1 are chosen to correctly to satisfy the formula. Put any standard value of either of the resistor (higher value of the resistor is recommended to reduce power loss), then substitute the value of required output voltage in the given formula to find the value of another resistor. For getting a steady and zero ripple output voltage, the linear voltage regulators IC’s are used. These are the integrated circuits that are made for linear voltage conversion and regulation are often termed as a step-down transformer ICs. Let’s discuss 12v to 5v DC converter using IC 7805. It works, BUT the device (or circuit) has to dissipate more power than is supplied to the load. It is even more inefficient than circuits 1 and 2, because the extra electronics take additional current. On the other hand, it would survive a short circuit and so is an improvement on circuits 2 and 3. It also limits the maximum current that would be taken under short circuit conditions, protecting the 12v source. The LM317 is an adjustable voltage regulator IC capable of supplying more than 1.0 Ampere of current with a wide range of o/p voltage from 1.25 Volts to 37 Volts. Its regulation is a little bit better than other fixed voltage-regulator IC like LM7805, 7806, 7808, 7810 …

Circuit 2 is a series Zener diode (or you could use a number of ordinary diodes in series to make up the voltage drop - say 12 x silicon diodes) All the circuits have different performance. The voltage divider circuit is not recommended for use in the high current application as it has a low output current and lower efficiency. LM7805 12v to 5v converter: The LT1173 consumes just 110µA supply current at standby, making it ideal for applications where low quiescent current is important. The device can deliver 5V at 80mA from a 3V input in step-up mode or 5V at 200mA from a 12V input in step-down mode. It is suggested to connect the input capacitor ‘Cin’ to work (as well as at output ‘recommended’). A heat sink as shown in the below figure must be there to dissipate heat (kind of extra i/p potential).The transformer IC 7805 is part of the LM78xx series of DC converter ICs. It is a linear step-down transformer IC. The digits ‘xx ‘ represents the value of the regulated o/p in volts. The IC7805 gives 5V DC as the digit ‘xx ‘ showing (05) which is 5 volts. The output will be constant at 5 Volts for all value of the input in 6.5volts to 35 volts. ( refer to datasheet) Few points worth mentioning: first, the “Cigar”, with its fixed USB output connector is providing voltage that is too high by proper USB standards. It could be due to old age or just bad quality. The difference is about 10% and I would consider it not usable. Second, most modules are capable of input voltages up to about 25 volts, but few can do 40 volts and higher. Kudos for that. Switching circuit properties Module Ps. Ripple measured with a Tektronix oscilloscope, maybe it is also possible to measure it with a multimeter set to AC Volts. Higher switching frequency will mean less ripple on the output (more accurate voltage/current) but causes more overhead due to switching, which reduces the efficiency a bit. A 12v to 5v dc converter can also be implemented with an LM317 voltage regulator IC. It is very useful in mid to high current applications(1 Amp and more). It is also found in desktop computers as voltage surge protection circuits.

And the winner is: “Fine”! This module is clearly the best for low power scenarios. When reaching currents of 100mA the differences between the 3 leading modules are minimal. The power supply for the test was providing 12V, but due to the voltage drop in the ammeter, the input voltage of the modules is a bit lower. Results The converter handles input current between 8-35V and provides a steady 5V/3A supply. It’s also waterproof and can be screwed into position. Of course, you may struggle to prove this is the case, leaving you without a device or a power supply converter.

There are many different reasons why you may need a 12V to 5V converter. If you are looking to reduce the supply and create a USB port then the Uctronics converter module could be the perfect solution for you.

A voltage regulator 12v to 5v dc can also be implemented with an LM7805 linear voltage converter. It is used for (10mA to 1 Amp ) medium current to the high current application circuits. It works, BUT most of the power is dissipated by the Zener diode. Not very efficient! On the other hand it does give a degree of regulation if the load changes. However, if you short circuit the output, the magic blue smoke will break free from the Zener... Such a short circuit may also damage the 12V source once the Zener is destroyed. The Drok 12V to 5V converter uses open wires that can be temporarily attached to a 12V supply and a 5V device. Of course, you can also solder them into a circuit to establish a more permanent connection. The Drok converter accepts input voltages of 12 and 9, it then converts them into 5 volts. Datasheets of some of the chips used in the modules contained an efficiency graph. The efficiency is a function of voltage and current. When available, I added the listed chip efficiency for the relevant Vin and Iout in the last column. Some modules have efficiency charts that don’t cover low current ranges, which might be an indication for the type of load the chips were (not) designed for. Output current of 25mA Module It works, BUT the output can be a bit spikey due to the high frequency switching nature of the device. However, it's very efficient because it uses stored energy (in an inductor and a capacitor) to convert the voltage. It has reasonable voltage regulation and output current limiting. It will survive a short circuit and protect the battery.

Overview

Many appliances rely on a 5 volt power supply. For example, any piece of equipment that gets its charge from a USB cable is likely to use 5 volts. If you attempt to put 12 volts through the device you are likely to blow the capacitors and could even cause your device to burst into flames. Yes, that includes your cell phone. I calculated the efficiency of each module per each type of load as: eff = Pin/Pout = (Vin*Iin)/(Vout*Iout) There are many applications associated with MC34063, a few of them are Human Machine Interface (HMI), Portable devise, Measurement and test, Gas and blood analyzer, computing, Telecommunications, Cable solutions, etc. 1N5819 Also, this IC is widely available and it is a lot more cost-efficient than the other ICs available in this segment. That is why we are going to use this IC for our circuit.

A wide range of IC’s and automation controller devices require 5 V DC supply for their operation, in the absence of 5 volt supply we might be needed to derive it from the existing power supply then comes these linear converter for help. Here’s the list of all possible circuits but their application differs from circuit to circuit. We already discussed 9v to 5v converter circuit previously. This module has the same connections as “Fine” but it is a bit larger. It was sold as “3A DC-DC 9V/12V/24V to 5V USB Step Down Power Module 2A Precise Vehicle Charger”. Voltage and currentOne 12v battery/ 12V adopter power source, 10uF capacitor, 1uF capacitor, IC LM7805, Heat-sink, some connecting wires, and a soldering iron (for soldering). One 12v battery, 100-ohm resistor ( higher value is recommended), 5.1V zener diode ( greater than 1W), some connecting wire, and soldering iron for permanent joints. Listed chip efficiency is within 5-10% of the measured module efficiency. The delta could be due to inefficiencies in the module itself or due to differences in the overall conditions (temperature, etc).