#Arduino uno r3 circuit diagram how to

#Arduino uno r3 circuit diagram how to

Related Articles on Arduino Power Supply SchematicĢ – How to Use MCP4725 Module with Arduinoģ – How to Use ADS1220 ADC Module with ArduinoĤ – How to Set up Arduino IDE for ESP8266 Programmingħ – NodeMCU V3 ESP8266 Pinout and ConfigurationĨ – How to Save and Restore ESP8266 and ESP32 Firmwareĩ – How to Control ESP-01 Without a Routerġ0 – How to Test NodeMCU V3 Using Esptool References on Arduino Power Supply Schematicġ – Arduino Uno on Wikipedia – the first thing to read when doing a researchĢ – Arduino Uno Schematic Diagram – complete documentation including interactive board viewerģ – Arduino Pro Mini clones 12V supply and 4B2X regulator – Arduino with 4B2X regulator getting friedĤ – Convert Arduino Uno Power Supply to 3.The pinout diagram of the Arduino Uno R3 development board contains 14 digital pins, 6 analog inputs, power jack, USB connection and ICSP header. The reason is that the ATMEGA328 chip has an absolute maximum rating of 6 volts. Furthermore, powering this terminal with a voltage greater than 6V may possibly break your Arduino board. These are:Īlso, besides losing some protections, be aware that the input voltage to the 5V terminal must be clean and well regulated. Four Ways of Powering Up The Arduino Power Supplyīased on the schematics above, we can see that there are four (4) different ways of powering up an Arduino board. As a result, it will allow the input voltage from the USB to connect to the 5V supply line. On the other hand, when the voltage from Vin disappears or goes down below 6.6 volts, the comparator turns on the MOSFET transistor. Subsequently, the USB connector voltage is disconnected from the 5V (or VCC) line. As a result the MOSFET transistor turns off. When the sampled Vin voltage is greater than or equal to 3.3 volts (>=3.3V), the op amp output goes up. This sampled Vin voltage is then compared to the output of the 3.3 volts regulator. Because the voltage divider uses two resistors of the same value, the voltage sampled is one half (1/2) of the Vin voltage. The op amp (LMV388) samples the Vin line thru a voltage divider (refer to the schematic above). However, since the DC jack is also connected to the Vin line, it is also compared with the USB connector when it is powered up (instead of the Vin input). So basically, the Arduino board only monitors the USB connector and the Vin input voltages. Also, you must refrain from powering the 5V pin together with the USB connector. If you look closely at the simplified schematic above, you will see that you should not simultaneously power the DC jack and the Vin pin. If Arduino finds an external voltage coming from either the Vin or the DC jack, it disconnects the USB connector VBUS (+5V) voltage. To prevent this from happening, Arduino monitors the Vin for the presence of any voltage. As a result, two or more input voltages may compete in supplying power to the board. As a matter of fact, in four different (4) ways. How the Auto Switching of USB Power WorksĪnyway, why, in the first place, is there a need for a switch on the USB connector? The schematics above show that the Arduino board accepts power in many ways. Its only use within the Arduino board is serving as a voltage reference for controlling the USB connector voltage.įinally, the simplified schematic shows that the USB connector connects to the 5V (and hence, VCC) thru a simplified switch. Its main purpose is for supplying external circuits with 3.3 volts. Observe that this 3.3V does not supply anything on the Arduino board. It comes out as a 3.3 volts that also terminates on the female header with a 3.3V label.

The 5-volt output of the regulator is also fed to the input of the 3.3V voltage regulator. Anyway, both AMS1117 and NCP1117 are the same 1117 device from two different manufacturers. However, the maximum input voltage is 18 volts, a two (2) volts difference from the NCP1117.

It has a similar dropout voltage of 1.2 volts. A quick check on the datasheet indicates that it is also a 1 ampere voltage regulator. In the Chinese Arduino clone that I have, the 5V voltage regulator is an AMS1117. In addition to that, it boasts of input operation up to 20 volts. Also, it has a maximum dropout voltage of 1.2 volts. According to the datasheet, it can output a current in excess of one (1) ampere. It is a three-terminal voltage regulator. In the original Arduino Uno R3e, this is a NCP1117ST50T3G chip. The main parts of the power supply are the two (2) voltage regulators, the op amp comparator, the MOSFET transistor, and the protection diode. In the picture above, the important parts of the Arduino power supply are all annotated. Arduino Uno R3 with the Power Supply Annotated