LF33CDT: High-Performance 3.3V Linear Voltage Regulator by STMicroelectronics

The LF33CDT from STMicroelectronics is a premium-grade linear voltage regulator delivering a fixed 3.3V output at up to 500mA current. Designed for precision power management, this IC is part of STMicroelectronics' renowned voltage regulator family, offering exceptional stability and efficiency for modern electronic systems. Below, we explore its technical specifications, applications, and why it remains a top choice despite its obsolete status.

Detailed Technical Specifications

Core Features

• Output Voltage: Fixed 3.3V ( 2% accuracy)
• Max Input Voltage: 16V
• Output Current: 500mA continuous
• Dropout Voltage: 0.7V @ 500mA (ensures efficient low-input operation)
• Quiescent Current: Just 1mA (ideal for battery-powered devices)

Advanced Performance Metrics

• PSRR: 80dB @ 120Hz (superior noise rejection for sensitive circuits)
• Operating Temp Range: -40 C to +125 C (industrial-grade reliability)
• Package: DPAK (TO-252-3) with thermal pad (optimized for heat dissipation)

Why Choose the LF33CDT?

1. Unmatched Voltage Stability

The LF33CDT maintains 2% voltage accuracy across all load conditions, critical for powering precision analog components and digital processors.

2. Robust Protection Features

• Automatic overcurrent protection (OCP)
• Thermal shutdown at 150 C (prevents damage from overheating)

3. Space-Efficient Design

The surface-mount DPAK package saves PCB space while providing excellent thermal performance through its integrated heatsink tab.

Comprehensive Applications

Industrial Systems

Perfect for PLCs, sensor modules, and control systems requiring stable 3.3V rails in harsh environments.

Consumer Electronics

• Wi-Fi modules
• IoT edge devices
• Portable medical equipment

Automotive Electronics

Used in infotainment systems and telematics where wide temperature operation is essential.

Design Considerations

Input Capacitor Selection

A 1 F ceramic capacitor is recommended at the input to suppress high-frequency noise.

Output Capacitor Requirements

Use a 10 F tantalum or 22 F aluminum electrolytic capacitor for optimal transient response.

Thermal Management

For continuous 500mA operation, ensure proper PCB copper area (minimum 50mm ) for heat dissipation.

Obsolete Status: What It Means

While marked obsolete by STMicroelectronics, the LF33CDT remains available through authorized distributors. Engineers can consider these alternatives:

• LD1117V33: Higher 800mA current version
• LM1117MPX-3.3: SOT-223 package alternative

Conclusion

The LF33CDT stands as a testament to STMicroelectronics' engineering excellence, delivering reliable 3.3V regulation for mission-critical applications. Its combination of low dropout, precise regulation, and robust protection makes it ideal for:

• Legacy system maintenance
• Cost-sensitive designs
• Applications requiring proven reliability

For engineers seeking guaranteed stock of the LF33CDT, we offer authentic parts with full traceability. Order today to secure your supply of this industry-proven voltage regulator.