The AMS1117 9V To 5V DC-DC Step-Down Power Supply Module 800mA is an ultra-compact, high-stability voltage regulation breakout board engineered to deliver a clean, ripple-free 5.0V DC power rail for microcontrollers, sensor arrays, radio modules, and digital logic circuits. Powered by the popular AMS1117-5.0 positive low-dropout linear regulator IC in an SOT-223 surface-mount package, it steps down unstable or higher-level DC sources (such as 9V batteries, 12V wall adapters, or unregulated battery banks) with tight ±1.5% voltage precision. Equipped with dual-row 2.54mm (0.1") gold-plated header pins, onboard input/output noise-filtering capacitors, and a red SMD power status LED, it is a staple power conditioning module for breadboard prototyping, custom carrier boards, and embedded systems.

Specifications

• Regulator IC: AMS1117-5.0 (Positive Low Dropout / LDO Linear Voltage Regulator)
• Input Voltage Range (V_IN): 6.0 V to 12.0 V DC (Nominal 9.0 V DC / Maximum Limit: 15.0 V DC)
• Regulated Output Voltage (V_OUT): 5.0 V DC (±1.5?curacy / ±0.075 V Tolerance)
• Maximum Continuous Output Current (I_OUT): Up to 800 mA to 1.0 A Max. (Subject to thermal dissipation limits)
• Recommended Continuous Load Current: 400 mA to 500 mA (For prolonged thermal reliability)
• Dropout Voltage (V_DROP): Typ. 1.1 V to 1.3 V at I_OUT = 800 mA
• Minimum Required Input Voltage: V_OUT + V_DROP ≈ 6.3 V DC (at full rated 800 mA load)
• Quiescent / Ground Current (I_Q): Approx. 5 mA to 11 mA
• Line Regulation: ≤ 0.2% (V_IN = 6.5 V to 12.0 V, I_OUT = 10 mA)
• Load Regulation: ≤ 0.4% (I_OUT = 10 mA to 800 mA)
• Ripple Rejection Ratio (PSRR): > 60 dB to 75 dB (at f = 120 Hz)
• Onboard Filtering Capacitors: Dual Surface-Mount Ceramic / Tantalum Capacitors (Input: 10 μF, Output: 10 μF / 22 μF for transient suppression)
• Status Indication: Onboard Red SMD Power Indicator LED (Tied across V_OUT with series resistor)
• Interface Pinout: Standard Dual-Row 2-Pin / 4-Pin 2.54 mm (0.1 Inch) Pitch Header Pins
• Thermal & Overcurrent Protection: Built-in Thermal Overload Protection (Junction Cutoff at T_J ≈ 150°C) and Internal Current Limiting (Short-Circuit Safe)
• Operating Temperature Range: -40°C to +125°C
• PCB Dimensions: Approx. 26 mm × 12 mm × 10 mm (L × W × H including male header pins)
• Net Weight: Approx. 2.0 g to 3.5 g

Pinout & Terminal Definition

• Input Interface (VIN / VCC): Positive Unregulated DC Input Rail (Connects to +6.0 V to +12.0 V DC, e.g., 9V Battery Positive terminal)
• Output Interface (VOUT / 5V): Regulated Positive 5.0 V DC Output Rail (Supplies logic circuits, sensors, and 5V microcontrollers)
• Ground Interface (GND): Common Negative Reference Ground (0 V) / Return path for both Input and Output circuits

Features

• Clean, Ripple-Free Linear Regulation: Operates without high-frequency switching noise, inductor whine, or EMI, making it ideal for powering noise-sensitive analog-to-digital converters (ADCs), audio preamplifiers, and precision analog sensors.
• Integrated Filtering Network: Onboard input and output bypass capacitors stabilize the internal feedback amplifier, eliminate parasitic self-oscillation, and smooth out line transients.
• Standard Breadboard Pitch (2.54mm): Pre-soldered single or dual-row header pins plug directly into solderless breadboards, perfboards, and female Dupont jumper cables.
• Comprehensive Built-In Silicon Safeguards: Integrates internal thermal shutdown circuitry and foldback short-circuit current limiting to prevent catastrophic semiconductor burnout under sustained faults.
• Convenient Visual Power Confirmation: Features an onboard red SMD LED that illuminates immediately upon successful regulation, providing quick diagnostic status.

Common Applications

• Microcontroller Core Power: Providing regulated 5V DC to Arduino Nano/Pro Mini, ATmega328P chips, PIC microcontrollers, and 8051 systems from 9V PP3 batteries or 12V adapters.
• Sensor Power Distribution: Clean power rail for 5V analog and digital modules (e.g., MQ gas sensors, ultrasonic rangefinders, Hall effect sensors, and analog strain gauges).
• Relay & Display Modules: Powering 5V electromechanical relay boards, I2C 1602 LCDs, and OLED displays from higher chassis supply rails.
• Audio & RF Receiver Front-Ends: Supplying low-noise DC power to FM receivers, wireless RF 433MHz decoders, and discrete audio op-amps (e.g., NE5532, LM358).
• Educational Prototyping: Compact plug-in power source for student STEM kits, breadboard experiments, and DIY robotics sensor shields.

Usage Tips

• Thermal Dissipation Calculation (CRITICAL):
  • As a linear regulator, the AMS1117 dissipates the voltage difference between input and output as pure waste heat: P_D = (V_IN - V_OUT) × I_OUT.
  • When stepping down from 9V to 5V (V_IN = 9.0 V, V_OUT = 5.0 V): Voltage drop is 4.0 V. If drawing 400 mA (0.4 A), power dissipated as heat is P_D = 4.0 V × 0.4 A = 1.6 W.
  • Because the SOT-223 package on this small PCB can safely dissipate approximately 0.8 W to 1.0 W without an external heatsink, keep continuous load currents below 200 mA to 250 mA when powering from a 9V or 12V source to avoid triggering thermal shutdown.
  • For high-current continuous loads (>500 mA from 9V/12V), consider adding a small clip-on copper/aluminum heatsink to the tab or switching to an inductive buck regulator (e.g., LM2596 or MP1584).
• Polarity Verification: The module does not feature a series reverse-polarity blocking diode. Verify that the positive supply line connects to VIN and the negative line connects to GNDbefore powering on; reversed input polarity will permanently destroy the AMS1117 IC.
• Dropout Voltage Headroom: Always maintain at least 1.3V difference between input and output (V_IN ≥ 6.3V). If an aging 9V alkaline battery drops below ~6.2V, the output voltage will fall below 5.0V, potentially causing microcontroller brownout resets.
• Output Short-Circuit Caution: While the IC features internal thermal and current limiting, sustained direct output short circuits at high input voltages (V_IN > 9V) will cause severe localized junction overheating and may damage the IC package over time.
• RF & Analog Isolation: For high-sensitivity analog circuitry (e.g., 24-bit ADCs or microphone preamps), place an additional 0.1 μF ceramic capacitor in parallel with a 100 μF low-ESR electrolytic capacitor directly across the output pins to eliminate residual low-frequency ripple.