AMS1117-3.3 - 3.3V Fixed-Output LDO Voltage Regulator (1A, SOT-223)

The AMS1117-3.3 is a 3.3V fixed-output low-dropout linear regulator rated for 1A output current with a maximum dropout voltage of 1.3V. It is housed in the industry-standard SOT-223 package and is pin-compatible with the LM1117-3.3 (Texas Instruments) and LD1117-3.3 (STMicroelectronics). At roughly $0.05–0.12/unit depending on volume, it is the most cost-effective 3.3V LDO in its class - making it the default choice for consumer electronics, IoT devices, and general-purpose 3.3V regulation where BOM cost is the primary driver. ICMASS maintains stock of AMS1117-3.3 in SOT-223 with flexible quantity options from sample to production reels.

What Are the Technical Specifications of AMS1117-3.3?

What Are the Alternatives to AMS1117-3.3?

Pin-Compatible Replacements

Functional Alternatives (Different Package/Current)

How Much Does AMS1117-3.3 Cost and Is It in Stock?

Last updated: 2026-06-08 | Warehouse: Shenzhen

What Are the Typical Applications of AMS1117-3.3?

• MCU/MPU Power Rails: The standard 3.3V rail for ARM Cortex-M, ESP32, STM32, and other microcontrollers. The AMS1117-3.3 provides adequate current at the lowest cost.
• Router & Networking Equipment: Regulates 5V to 3.3V for SoC and Ethernet PHY on router mainboards. SOT-223 package fits space-constrained layouts.
• LED Display Driver Power: Provides a clean 3.3V rail for multiple LED driver ICs. The 1A rating handles shift register arrays in large panels.
• IoT Sensor Modules: Devices with stable 5V USB input benefit from the low cost and adequate performance of the AMS1117-3.3.
• Breakout Boards & Dev Kits: The de-facto standard for 3.3V regulation on hobbyist and prototyping boards - found on Arduino, ESP32, and STM32 dev boards.

Why Buy AMS1117-3.3 from ICMASS?

• Shenzhen sourcing advantage: We source directly from the supply chain. Our pricing reflects current market conditions, not a static catalog.
• Stock verification before shipment: Every AMS1117-3.3 order is physically verified for quantity, packaging, and visual authenticity markers before shipping.
• Counterfeit screening: AMS1117-3.3 is one of the most commonly counterfeited LDOs. We actively screen for known counterfeit markers including incorrect marking, pin 1 orientation, and packaging anomalies.
• Flexible quantity: From 1 piece for prototyping to full reels of 4,000 units - same fulfillment process.

Frequently Asked Questions About AMS1117-3.3

Q1: What is the minimum input voltage for AMS1117-3.3 to maintain regulation?
A: The minimum input voltage is 4.6V (3.3V output + 1.3V max dropout). With a 5V ±5% rail (4.75–5.25V), the tolerance is tight. A 5V ±3% supply is safer. For battery-powered designs, the AMS1117-3.3 is not suitable - use a low-dropout LDO like XC6206 (200mV dropout) instead.

Q2: Can I use AMS1117-3.3 with 3.7V lithium batteries?
A: Not directly. A fully charged 3.7V Li-ion is 4.2V - below the 4.6V minimum input. At 3.8V battery voltage, the output drops below 2.8V. For battery-powered 3.3V designs, use an LDO with <300mV dropout (XC6206, AP2112) or a boost converter.

Q3: Can AMS1117-3.3 deliver 1A continuously?
A: Yes, with adequate thermal management. At 1A with 5V input, power dissipation is (5V - 3.3V) × 1A = 1.7W. The SOT-223 junction-to-ambient thermal resistance (θJA) is about 62°C/W on 1oz copper, yielding ~105°C temperature rise - within the 125°C limit but requiring good PCB heatsinking. For continuous 1A, consider the TO-252 package variant or add thermal vias under the tab.

Q4: What's the difference between AMS1117-3.3 and LM1117-3.3?
A: Two key differences: accuracy (AMS1117 ±1.5% vs LM1117 ±1.0%) and counterfeit risk (AMS1117 is widely counterfeited). At $0.08 vs $0.13/unit, the AMS1117 costs about 60% less. For digital-only designs, the difference is negligible. For mixed-signal or industrial designs, the LM1117 premium is worth it for the tighter regulation and cleaner supply chain.

Q5: What capacitors does AMS1117-3.3 require?
A: The datasheet recommends 10µF tantalum or aluminum electrolytic on both input and output. For ceramic capacitors, use X5R/X7R dielectric with at least 10µF output and 4.7µF input. Output capacitor ESR should be between 0.1Ω and 5Ω for loop stability.

Q6: Is AMS1117-3.3 a good choice for battery-powered IoT sensors?
A: Not ideal. The 5mA quiescent current is high by modern standards. For battery-powered designs spending most time in sleep mode, consider an LDO with <1µA quiescent current (TPS7A16, XC6206). The AMS1117's 5mA baseline would drain a 200mAh battery in 40 hours even in sleep.

Q7: How do I identify counterfeit AMS1117-3.3?
A: Common counterfeit markers include: incorrect logo font or laser marking weight (lighter than genuine), different package dimensions, pin 1 orientation inconsistent with datasheet, and batch numbers that don't match manufacturer format. From our sourcing experience, the most common fake is a lower-spec part re-marked as AMS1117-3.3.

Q8: Can I replace a blown AMS1117-3.3 with LM1117-3.3?
A: Yes, they are pin-compatible in SOT-223 and TO-252 packages. LM1117-3.3 is a direct drop-in replacement with slightly better specs. No PCB change needed.

Q9: Does AMS1117-3.3 have reverse polarity protection?
A: No. The AMS1117 series does not include reverse polarity protection. Reverse voltage can damage the regulator and downstream components. Add a series diode or P-channel MOSFET reverse protection circuit if needed.

Q10: What is the typical output noise?
A: 120µVrms over 10Hz–100kHz. This is moderate for an LDO. For noise-sensitive applications (audio, ADC reference), consider the LP5912-3.3 (12µVrms) or LM1117-3.3 (90µVrms).

Q11: Can I parallel two AMS1117-3.3 for more current?
A: Not recommended. LDOs in parallel do not share current equally due to manufacturing tolerances in output voltage. One unit will take most of the current and may enter thermal shutdown. Use a single higher-current regulator or a DC-DC converter.

Q12: What is the difference between AMS1117-3.3 and AMS1117-ADJ?
A: AMS1117-3.3 has a fixed 3.3V output with internal resistor divider. AMS1117-ADJ requires two external resistors to set the output (VOUT = 1.25V × (1 + R2/R1)). Fixed version saves BOM cost and board space for 3.3V-only designs.

Q13: What is the operating temperature range?
A: Standard AMS1117-3.3 is rated 0°C to +125°C. For industrial (-40°C to +125°C) applications, check if the specific variant meets extended temperature specs or consider LM1117IMP-3.3 which is rated for -40°C.

Q14: Is AMS1117-3.3 RoHS compliant?
A: Yes, available in RoHS-compliant versions. Check the specific suffix (e.g., AMS1117-3.3V vs AMS1117-3.3-E1) for compliance status. Standard lead-free version uses matte tin plating.

Q15: What's the standard reel quantity for AMS1117-3.3 in SOT-223?
A: Standard SOT-223 reels are 2,500 or 4,000 units depending on manufacturer. Some suppliers offer 1,000-unit cut tapes for smaller production runs.

Internal Links

• LM1117-3.3 Product Page - Higher accuracy alternative
• AMS1117 vs LM1117 vs LD1117 Comparison - Full comparison guide
• LDO vs DC-DC vs Adjustable Comparison - Power regulator selection guide