The maximum output of an Arduino is primarily defined by the current it can safely supply from its digital/analog pins and the total current the entire board can handle. Individually, a digital or analog pin can continuously supply up to 20 mA (milliamperes), while the entire Arduino board typically has a total continuous current output capacity ranging from 200 to 400 mA.
Understanding Arduino's Electrical Output Capabilities
When discussing Arduino's "output," it generally refers to the electrical power (voltage and current) it can deliver from its general-purpose input/output (GPIO) pins to external components. It's crucial to understand both the voltage level and the current limits to prevent damage to the Arduino or connected devices.
Digital Pin Voltage Output
Most standard Arduino boards, such as the Arduino Uno, operate at a 5V logic level. This means that when a digital pin is set to HIGH, it outputs approximately 5 volts. Some newer or more advanced Arduino boards, like the Arduino Due, use a 3.3V logic level.
- 5V Boards: Arduino Uno, Mega, Leonardo, Nano.
- 3.3V Boards: Arduino Due, MKR series, and many ESP32-based compatible boards.
It's vital to ensure that any component connected to an Arduino's output pin is compatible with its operating voltage.
Current Output Per Digital/Analog Pin
Each individual digital or analog output pin on an Arduino board is designed to safely supply a limited amount of current. The maximum current a connected device can continuously draw from a single pin is 20 mA. While some microcontrollers might have an absolute maximum rating of 40 mA per pin, continuously drawing more than 20 mA is highly discouraged and can lead to:
- Damage to the microcontroller: Overcurrent can burn out the internal circuitry of the pin.
- Unreliable operation: The voltage output might drop, leading to inconsistent behavior.
- Reduced lifespan: Stressing the pins continuously can shorten the board's overall life.
For example, a standard LED typically requires around 10-20 mA with an appropriate current-limiting resistor. Driving a single LED directly (with a resistor) is well within the pin's capabilities.
Total Current Output for the Arduino Board
Beyond the per-pin limit, the entire Arduino board also has a maximum total current capacity. The maximum current that can pass through an Arduino in total from all its output pins combined is approximately 200-400 mA. This is a critical limit for the onboard voltage regulator and the microcontroller itself.
- Example: If you connect multiple LEDs, each drawing 15 mA, you can power about 13-26 LEDs simultaneously (depending on the exact board and its total current limit) without exceeding the total board capacity.
- Consequence of exceeding: Drawing more than the total capacity can cause the voltage regulator to overheat and potentially fail, leading to unstable operation or permanent damage to the Arduino.
Input Voltage Management
While not an "output" specification, understanding the input voltage capability is crucial for powering the Arduino itself. The Arduino's onboard voltage regulator can manage a typical maximum source voltage of 12V when powering the board through the DC jack or VIN pin. Providing an input voltage higher than this (e.g., 20V) can overheat and damage the voltage regulator, even if the output current drawn is low.
Practical Solutions for Higher Power Needs
If your project requires driving components that need more than 20 mA per pin or a total current exceeding the board's 200-400 mA limit, you cannot power them directly from the Arduino. Instead, you need external circuitry:
- Transistors or MOSFETs: These act as electronically controlled switches. The Arduino's low-current output (e.g., 5V, 20 mA) can switch a transistor, which then controls a much larger current drawn directly from an external power supply to your high-power component (e.g., a motor, multiple LEDs).
- Relays: For AC loads or very high DC loads, relays provide electrical isolation between the Arduino and the high-power circuit. The Arduino switches a small coil current, which in turn operates a physical switch for the high-power circuit.
- External Power Supplies: For components like powerful motors, multiple LED strips, or solenoids, always use a dedicated external power supply. The Arduino's role then becomes sending control signals to activate these components via transistors or relays.
Summary of Arduino Output Specifications
| Specification | Typical Value | Notes |
|---|---|---|
| Digital Pin Voltage | 5V or 3.3V | Varies by specific Arduino board model |
| Current Per Digital Pin | 20 mA (continuous) | Recommended maximum for reliable, long-term operation |
| Total Board Current | 200-400 mA | Sum of currents drawn from all active pins; varies by board |
| Maximum Input Voltage | 12V (regulator) | Maximum typical voltage for the onboard voltage regulator input |
