Description
The AMS1117-3.3V LDO Voltage Regulator Module is a compact, high-performance linear voltage regulator board designed to provide a stable and clean 3.3V DC output from a higher voltage DC input. Built around the renowned AMS1117-3.3 low-dropout regulator (LDO), this module is an essential building block for countless electronics projects, microcontroller applications, and prototype development requiring a reliable 3.3V power source.
The AMS1117 series is a popular family of low-dropout linear regulators known for their simplicity, reliability, and excellent performance. This fixed 3.3V version accepts a wide input voltage range (typically 4.5V to 15V DC) and steps it down to a precise 3.3V output with a maximum current of up to 800mA to 1A (depending on cooling and input voltage conditions) . The module features a very low dropout voltage—the minimum difference required between the input and output for proper operation—of approximately 1.1V to 1.3V at full load . This allows you to power your 3.3V circuits from common 5V USB supplies, 9V batteries, or 12V wall adapters.
The onboard AMS1117-3.3 integrates essential protection features, including over-current protection (current limiting) and thermal shutdown, safeguarding your downstream circuitry and the regulator itself from damage during fault conditions . The regulator’s output voltage is trimmed for high accuracy, typically within ±1% to ±1.5% of the ideal 3.3V .
This module simplifies the use of the AMS1117 by breaking out the three essential pins (Input, Ground, Output) to easy-to-use pin headers or screw terminal blocks. A power indicator LED is included to visually confirm that the output is active . Many variants also feature mounting holes, allowing for secure attachment within your project enclosure.
The board is typically designed with a very simple and straightforward layout, requiring only input and output filtering capacitors (often included on the module) for stable operation. This makes it an ideal “plug-and-play” solution for developers who need a reliable 3.3V rail without designing a custom power supply circuit.
Whether you need to power a 3.3V microcontroller (like ESP8266, ESP32, or STM32), a sensor module, a wireless communication chip, or simply create a dedicated 3.3V test point on your workbench, the AMS1117-3.3V LDO Voltage Regulator Module provides a simple, effective, and reliable solution for all your voltage regulation needs.
Key Features
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Fixed 3.3V Output – Provides a stable, regulated 3.3V DC output perfect for modern microcontrollers and 3.3V logic circuits
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Wide Input Voltage Range – Accepts DC inputs from 4.5V to 15V, making it compatible with 5V USB, 9V batteries, and 12V adapters
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800mA Output Current – Capable of delivering up to 800mA of continuous output current (1A peak, derate based on cooling)
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Low Dropout Voltage – Requires only a 1.1V to 1.3V difference between input and output to maintain regulation, allowing efficient operation from 5V inputs
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Integrated Protection – Features built-in over-current limiting and thermal shutdown protection for reliable, fail-safe operation
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High Ripple Rejection – 75dB PSRR at 10kHz provides excellent power supply ripple rejection for noise-sensitive applications
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Low Quiescent Current – Consumes a very low operating current (5-10mA), making it suitable for power-sensitive applications
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Easy to Use – Simple 3-pin interface (Input, Ground, Output) on pin headers or screw terminals for quick, solderless wiring
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Visual Indicator – Onboard power LED provides instant visual confirmation that the module is powered and the output is active
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Compact Form Factor – Small footprint (approximately 13mm x 9mm), ideal for space-constrained projects and breadboard integration
Technical Parameters
Usage Guide
How It Works
The AMS1117 is a classic low-dropout linear regulator. It operates by using a control loop to adjust the resistance of an internal power transistor. This transistor acts like a variable resistor, dropping the excess input voltage and dissipating it as heat to maintain a constant, stable 3.3V at the output pin . The module is ready to use; simply provide a suitable DC input voltage on the designated input terminal, and the regulated 3.3V output will be available on the output terminal.
Pinout and Connections
The module provides access to all three pins of the AMS1117 regulator. While the labeling and arrangement may vary by manufacturer, the functions are universal .
Typical Wiring Diagram:
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Connect Input Power: Attach the positive terminal (+) of your DC power supply (e.g., 5V USB, 9V battery, or 12V adapter) to the IN terminal
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Connect Ground: Attach the negative terminal (-) of your power supply to the GND terminal
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Connect Your Load: Attach the positive (VCC) wire of your 3.3V device (e.g., ESP8266, sensor, or logic circuit) to the OUT terminal
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Complete the Load Circuit: Connect the ground (GND) of your 3.3V device to the GND terminal on the module
Important Usage Considerations
Input Voltage (VIN)
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Minimum Input: For stable operation at the full 800mA output, the input voltage must be at least VOUT + Dropout Voltage, or approximately 4.5V to 4.8V. A 5V supply is the most common and efficient choice .
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Maximum Input: The absolute maximum input voltage is 15V . Exceeding this can permanently damage the regulator. For 12V inputs, ensure adequate heat dissipation.
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Efficiency & Heat: An LDO like the AMS1117 is not 100% efficient. The wasted power is calculated as (VIN - VOUT) × ILOAD and is dissipated as heat . For example, with a 12V input and a 300mA load, the module must dissipate (12V - 3.3V) × 0.3A = 2.61W of heat. At higher currents and voltages, the module will become very hot.
Output Current (IOUT)
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The theoretical maximum current is 1A . However, the practical safe current is 800mA under ideal conditions and depends heavily on how much heat the module can dissipate .
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For a 12V input, it is recommended to keep the load well under 300mA to prevent overheating.
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For high-current applications at higher voltages, a switching (buck) converter is a much more efficient solution.
Power Indicator LED
Heat Management
The AMS1117 can get hot, especially when converting a high voltage (e.g., 12V) to 3.3V at a moderate current. Consider the following:
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Test Before Enclosing: Always test your circuit and feel the temperature of the regulator IC. If it is too hot to touch comfortably, you need to reduce the current, lower the input voltage, or add a heat sink.
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Heat Sinking: The regulator’s metal tab is often connected to ground. You can glue or solder a small stick-on heat sink to this tab to improve cooling.
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PCB Layout: If designing a custom board, providing a generous area of copper connected to the regulator’s ground pin can help wick away heat.
Typical Applications
Applications
This module is ideal for:
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Powering 3.3V microcontrollers (ESP8266, ESP32, STM32)
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Providing a stable 3.3V rail for sensors and modules
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Step-down conversion from 5V USB to 3.3V for development boards
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Creating a dedicated 3.3V power supply for breadboard experiments
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Replacing the inadequate 3.3V regulator on some development boards
Q: What is the minimum input voltage to get a stable 3.3V output?
The AMS1117-3.3 has a dropout voltage of approximately 1.1V to 1.3V at full current . This means the input must be at least 4.4V to 4.6V. A 5V supply is the perfect and most common choice, providing a comfortable 0.7V to 1.0V of headroom.
Q: Can I power this module from a 3.7V Lithium-Ion battery?
Not directly. A fully charged Li-ion cell is 4.2V, which is at the very edge of the regulator’s minimum input range. As the battery discharges to its nominal 3.7V, the voltage will drop below the minimum required input, and the module’s output will fall out of regulation and drop below 3.3V. For battery-powered applications, you should use a low-dropout regulator (LDO) specifically designed for single-cell Li-ion operation or use a boost converter.
Q: Why is my AMS1117 module getting extremely hot?
This is the most common issue with linear regulators. The heat is the result of wasted power being dissipated. Use the formula: Power = (VIN – VOUT) × ILOAD .
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Example: With VIN = 12V, VOUT = 3.3V, and ILOAD = 300mA, the power dissipated is (12 - 3.3) × 0.3 = 2.61W. This is a significant amount of heat for a small SOT-223 package.
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Solutions: Reduce the input voltage (use 5V if possible), reduce the current draw of your load, or attach a small heatsink to the regulator’s tab. For high-current or high-voltage-difference applications, a switching buck converter is recommended
Q: What is the maximum current I can draw from this module?
The AMS1117 chip is rated for a maximum of 800mA to 1A . However, the practical limit depends on the input voltage and cooling. With a 5V input and good airflow, you can reliably draw 600-700mA. With a 12V input, you should limit the current to 150-250mA to prevent overheating
Q: What are the "IN", "GND", and "OUT" terminals on the module for?
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IN (Input): This is where you connect your unregulated higher voltage power source (e.g., +5V, +9V, or +12V)
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GND (Ground): This is the common ground reference for both the input and output. You must connect the ground of your power source and the ground of your load to this terminal
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OUT (Output): This is the regulated 3.3V output. You connect the positive power input of your 3.3V device (microcontroller, sensor, etc.) to this pin
Q: Can I use this module to power an ESP8266 or ESP32 from a 5V source?
Yes, absolutely! This is one of the most common use cases. Both ESP8266 and ESP32 require a stable 3.3V supply and can draw significant current (up to 300-400mA during Wi-Fi transmission). The AMS1117-3.3V module powered from a 5V USB source is an excellent way to provide the required power.
Wiring: Connect 5V to the module’s IN, module’s GND to ESP GND, and module’s OUT to ESP’s 3.3V pin.
Q: What is the difference between the AMS1117 module and a buck converter module?
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AMS1117 (Linear Regulator): Simple, cheap, and provides very clean, low-noise output. Its main downside is inefficiency; it wastes excess voltage as heat, making it poor for large voltage drops or high currents .
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Buck Converter (Switching Regulator): More complex and can produce electrical noise (ripple) on its output. However, it is highly efficient (85-95%) and does not get hot, making it ideal for stepping down large voltages (e.g., 12V to 3.3V) or for battery-powered projects.
For most microcontroller and sensor projects powered from a clean 5V source at modest currents (<500mA), the AMS1117 is an excellent choice.
Q: My output is 3.1V, not 3.3V. What's wrong?
This usually indicates that the input voltage is too low or that the module is overheating. Check the following:
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Input Voltage: Measure the voltage on the IN pin. Is it at least 4.5V under load? If you’re using a 5V supply, measure it under load; some cheap USB chargers can drop to 4.0V or lower, which is insufficient.
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Current Limit: Your load might be drawing too much current, causing the regulator to drop out or go into thermal shutdown. Disconnect your load and measure the output voltage. If it returns to 3.3V, your load is too heavy.
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Heat: Is the regulator extremely hot? It may be in thermal shutdown. Allow it to cool and reduce your current or input voltage.
Q: Can I use this module for both home and business applications?
Home users: Powering ESP8266/ESP32 projects from 5V USB power banks or old phone chargers, creating a dedicated 3.3V supply for breadboard experiments, powering 3.3V sensors for home automation, and DIY electronics projects .
Business users: Providing a clean 3.3V rail for prototype development and testing, powering industrial sensors and 3.3V logic circuits, creating dedicated test benches, and as a local power point in larger embedded systems where efficiency is not the primary concern.
Q: Does this module have short-circuit protection?
Yes. The AMS1117 chip itself has built-in over-current limiting protection and thermal shutdown . If you short the OUT pin directly to GND, the regulator will limit its output current to a safe level (typically around 1.0A to 1.2A) and will shut down if it overheats. This protects both the regulator and your circuit. However, this is a protective feature for the chip, not a substitute for proper fusing in a safety-critical system.
