LD1117AS33TR: High-Performance 3.3V 1A Linear Voltage Regulator by STMicroelectronics

The LD1117AS33TR is a premium-grade low dropout (LDO) linear voltage regulator manufactured by STMicroelectronics, a global leader in semiconductor solutions. Designed for precision power management, this regulator delivers a fixed 3.3V output with exceptional stability and efficiency, making it ideal for a wide range of electronic applications. In this comprehensive guide, we'll explore its technical specifications, key features, and practical applications to help you understand why this component is a top choice for engineers worldwide.

Product Overview and Manufacturer Background

About STMicroelectronics

STMicroelectronics is a multinational semiconductor manufacturer headquartered in Geneva, Switzerland. With a reputation for innovation and quality, STMicroelectronics produces a wide range of electronic components, including the LD1117 series of voltage regulators that are renowned for their reliability and performance.

Product Classification

• Manufacturer: STMicroelectronics
• Primary Category: Integrated Circuits (ICs)
• Secondary Category: PMIC - Voltage Regulators - Linear
• Regulator Type: Low Dropout (LDO) Voltage Regulator

Detailed Technical Specifications

Electrical Characteristics

• Output Voltage: Fixed 3.3V 1% accuracy
• Maximum Input Voltage: 15V DC
• Output Current: Up to 1A continuous
• Dropout Voltage: 1.3V maximum at full load (1A)
• Line Regulation: 0.2% (typical)
• Load Regulation: 0.4% (typical)
• Quiescent Current: 10mA (typical)
• Operating Temperature Range: 0 C to +125 C

Performance Features

• Power Supply Rejection Ratio (PSRR): 75dB @ 120Hz
• Thermal Resistance: 60 C/W (junction-to-ambient)
• Protection Circuits:
  • Over-current protection
  • Thermal shutdown
  • Safe operating area protection

Package Information and Physical Dimensions

The LD1117AS33TR comes in a compact SOT-223 surface-mount package (TO-261-4 variant) that offers excellent thermal performance in a small footprint:

• Package Dimensions: 6.5mm 7.0mm 1.8mm
• Pin Configuration:
  1. Input Voltage (VIN)
  2. Ground (GND)
  3. Output Voltage (VOUT)
  4. Tab (connected to VOUT for heat dissipation)
• Mounting Style: Surface Mount Technology (SMT)
• Lead Material: Matte Tin-plated copper

Key Advantages and Competitive Features

Why Choose the LD1117AS33TR?

1. High Accuracy: Maintains 3.3V output within 1% tolerance across varying loads and temperatures
2. Low Dropout Voltage: Only 1.3V at maximum load enables efficient operation with lower input voltages
3. Excellent Thermal Performance: SOT-223 package with thermal pad provides effective heat dissipation
4. Robust Protection: Built-in safeguards against over-current and over-temperature conditions
5. Low Noise Output: High PSRR (75dB) ensures clean power for sensitive circuits
6. Wide Temperature Range: Operates reliably from 0 C to +125 C

Typical Applications and Use Cases

The LD1117AS33TR is versatile enough for numerous applications across various industries:

Consumer Electronics

• Power supply for microcontrollers (Arduino, STM32, PIC)
• Voltage regulation in smart home devices
• Portable media players and handheld gaming systems

Industrial Applications

• PLC (Programmable Logic Controller) power circuits
• Industrial sensor networks
• Motor control systems

Telecommunications

• Base station power management
• Network router/switching equipment
• RF module power supplies

Automotive Electronics

• Infotainment systems
• ECU (Engine Control Unit) peripherals
• Dashboard instrumentation

Design Considerations and Implementation Tips

Input/Output Capacitor Selection

For optimal performance:

• Input Capacitor: 10 F ceramic or tantalum capacitor recommended
• Output Capacitor: Minimum 22 F with ESR between 0.1 and 1
• Placement: Locate capacitors as close as possible to the regulator pins

Thermal Management

To prevent thermal shutdown:

• Use adequate copper area for heat dissipation
• Consider adding thermal vias under the package
• For high ambient temperatures, calculate power dissipation using:

  P_DISS = (V_IN - V_OUT) I_OUT

PCB Layout Guidelines

• Keep high-current traces short and wide
• Separate analog and digital ground planes
• Place the regulator close to the load to minimize voltage drops

Comparison with Similar Voltage Regulators

Parameter	LD1117AS33TR	AMS1117-3.3	LM1117MPX-3.3
Manufacturer	STMicroelectronics	AMS	Texas Instruments
Output Current	1A	1A	800mA
Dropout Voltage	1.3V @ 1A	1.3V @ 1A	1.2V @ 800mA
Package	SOT-223	SOT-223	SOT-223
Price Range	$$	$	$$$

Frequently Asked Questions

Q1: Can the LD1117AS33TR handle input voltages below 4.6V?

A: Yes, but the output may not maintain regulation. The minimum input voltage is V_OUT + V_DROP (3.3V + 1.3V = 4.6V) for full 1A load. For lighter loads, the dropout voltage decreases.

Q2: Is a heatsink required for this regulator?

A: For continuous operation at 1A with significant input-output differential, proper PCB copper area or a small heatsink is recommended. The SOT-223 package can dissipate about 1W without additional heatsinking in typical conditions.

Q3: Can multiple LD1117AS33TR regulators be paralleled for higher current?

A: Not directly. For higher currents, consider using a switching regulator or a dedicated high-current LDO. Paralleling LDOs requires current-sharing circuits.

Q4: What's the typical lifespan of this regulator?

A: When operated within specifications, the LD1117AS33TR typically exceeds 50,000 hours MTBF (Mean Time Between Failures).

Purchasing Information and Resources

The LD1117AS33TR is available through authorized distributors worldwide. For design support:

• Download the official datasheet from STMicroelectronics
• Access SPICE models for simulation
• Request sample units for prototyping

Conclusion

The LD1117AS33TR from STMicroelectronics represents an optimal balance of performance, reliability, and cost for 3.3V power regulation needs. Its combination of low dropout voltage, high current capability, and robust protection features make it suitable for demanding applications across consumer, industrial, and automotive sectors. Whether you're designing a simple microcontroller board or a complex industrial system, this voltage regulator provides the stable, clean power that modern electronics require.

For engineers seeking a proven 3.3V regulator solution, the LD1117AS33TR offers exceptional value with STMicroelectronics' quality assurance. Its widespread availability and comprehensive documentation further simplify the design-in process, making it a go-to choice for power management challenges.