LM2940CT-5.0 1A Low Dropout Voltage Regulator

Overview

The LM2940CT-5.0 is a fixed 5V positive voltage regulator capable of supplying 1A of output current with excellent line and load regulation characteristics. This low-dropout regulator features a typical dropout voltage of just 0.5V (1V maximum) across the full operating temperature range, making it particularly suitable for battery-powered applications where input voltage may approach the output voltage.

Designed with robust protection features, the LM2940CT-5.0 is well-suited for automotive and industrial applications where electrical transients and harsh operating conditions may be encountered. The device includes built-in protection against reverse battery conditions, load dump transients, and short circuits.

Key Features

• 1A guaranteed output current
• Low dropout voltage: 0.5V typical (1V max)
• Quiescent current reduction circuit (30mA typical at 5V differential)
• Fixed 5V output voltage (±2% tolerance)
• Built-in protection features:
  • Reverse battery protection
  • Load dump transient protection (up to 60V)
  • Short circuit protection
  • Thermal shutdown
• Wide operating temperature range: -40°C to +125°C
• Mirror-image insertion protection
• TO-220 package for easy mounting and heat dissipation

Applications

The LM2940CT-5.0 is ideal for a wide range of applications requiring stable, regulated 5V power:

• Automotive electronics:
  • ECU power supplies
  • Infotainment systems
  • Instrument clusters
• Industrial control systems
• Battery-powered equipment
• Microprocessor and microcontroller power supplies
• Peripheral device power regulation
• Embedded systems
• Point-of-load regulation

Electrical Characteristics

All specifications are for T_J = 25°C, V_IN = V_OUT + 5V, I_OUT = 500mA, C_IN = 0.33μF, and C_OUT = 0.1μF unless otherwise noted.

Absolute Maximum Ratings

• Input Voltage: -50V to +60V
• Operating Junction Temperature Range: -40°C to +125°C
• Storage Temperature Range: -65°C to +150°C
• Lead Temperature (Soldering, 10 sec): 260°C

Electrical Specifications

• Output Voltage: 5V ±2%
• Output Current: 1A (maximum)
• Dropout Voltage:
  • 0.5V typical (I_OUT = 1A)
  • 1V maximum (I_OUT = 1A, T_J = -40°C to +125°C)
• Line Regulation: 0.04% typical (V_IN = 6V to 26V)
• Load Regulation: 0.3% typical (I_OUT = 5mA to 1A)
• Quiescent Current:
  • 30mA typical (V_IN - V_OUT = 5V)
  • 10mA maximum (V_IN - V_OUT ≥ 3V)
• Ripple Rejection: 65dB typical (f = 120Hz)
• Output Noise Voltage: 100μV typical (10Hz to 100kHz)

Package Information

The LM2940CT-5.0 is available in a standard TO-220 package with the following mechanical characteristics:

TO-220 Package Dimensions

• Package Type: TO-220-3
• Mounting Style: Through Hole
• Number of Pins: 3
• Lead Pitch: 2.54mm
• Package Length: 10.16mm
• Package Width: 4.58mm
• Package Height: 8.89mm
• Lead Length: 3.3mm
• Weight: 2.3g typical

Thermal Characteristics

• Junction-to-Ambient Thermal Resistance (R_θJA): 50°C/W
• Junction-to-Case Thermal Resistance (R_θJC): 5°C/W
• Maximum Junction Temperature: 125°C

Typical Performance Characteristics

The LM2940CT-5.0 exhibits excellent performance across its operating range:

• Stable output voltage with varying input voltage (6V to 26V)
• Minimal output voltage variation with load current changes (5mA to 1A)
• Low dropout voltage maintained across full temperature range
• Excellent transient response to load steps
• Effective ripple rejection for noisy input supplies

Design Considerations

Input and Output Capacitors

For optimal performance, the following capacitor selection is recommended:

• Input Capacitor: 0.33μF tantalum or aluminum electrolytic
• Output Capacitor: 0.1μF ceramic or 1μF tantalum

Thermal Management

When operating at high currents or high ambient temperatures, proper heat sinking is required to maintain junction temperature within safe limits. The TO-220 package is designed for easy attachment of heat sinks.

Protection Features

The built-in protection features make the LM2940CT-5.0 particularly robust:

• Automatic shutdown during excessive input voltage transients
• Survival under reverse battery conditions (-50V)
• Current limiting and thermal shutdown for overload protection

Conclusion

The LM2940CT-5.0 provides a reliable, high-performance voltage regulation solution for demanding applications. Its combination of low dropout voltage, robust protection features, and 1A output current capability make it an excellent choice for automotive, industrial, and battery-powered systems requiring stable 5V power.