LM2941C Low Dropout Voltage Regulator Technical Summary

Overview

The LM2941C is a high-performance, low-dropout (LDO) positive voltage regulator capable of delivering up to 1A of output current. Designed for demanding applications, it features a typical dropout voltage of just 0.5V (1V maximum across the full temperature range). The device incorporates advanced quiescent current reduction technology, making it particularly suitable for battery-powered systems where power efficiency is critical.

Engineered with robust protection features, the LM2941C is well-suited for automotive and industrial applications where reliability under harsh conditions is essential. The regulator maintains stable operation during input voltage transients and includes comprehensive protection against reverse polarity, overcurrent, and thermal overload conditions.

Key Features

• High Current Capability: 1A continuous output current
• Low Dropout Voltage: 0.5V typical (1V max across temperature range)
• Quiescent Current Reduction: Automatically reduces ground pin current when input-output differential exceeds ~3V
• Low Quiescent Current: Only 30 mA at 1A output with 5V input-output differential
• Robust Protection Features:
  • Reverse battery protection
  • Two-battery jump start protection
  • Automatic shutdown during input voltage transients
  • Short circuit protection
  • Thermal overload protection
• Wide Operating Temperature Range: Suitable for industrial and automotive applications
• Stable with Low-ESR Capacitors: Designed for stability with inexpensive capacitors

Applications

The LM2941C is ideal for a wide range of applications requiring stable voltage regulation under varying load conditions:

Automotive Systems

• Engine control units
• Infotainment systems
• Body electronics modules
• Advanced driver assistance systems (ADAS)

Industrial Equipment

• PLC systems
• Motor control circuits
• Sensor networks
• Power management for embedded systems

Consumer Electronics

• Portable devices
• Battery-powered equipment
• Set-top boxes
• Home automation systems

Computing Systems

• Peripheral power supplies
• Motherboard voltage regulation
• Storage device power management

Electrical Characteristics

The following table summarizes the key electrical specifications of the LM2941C:

Absolute Maximum Ratings

• Input Voltage: 26V (transient), 20V continuous
• Power Dissipation: Internally limited by thermal shutdown
• Operating Junction Temperature: -40°C to +125°C
• Storage Temperature: -65°C to +150°C

Operating Characteristics (T_J = 25°C, unless otherwise specified)

• Output Voltage Options: Fixed 5V, 8V, 10V, 12V or adjustable from 5V to 20V
• Line Regulation: 0.3% typical (1% max)
• Load Regulation: 0.4% typical (1% max)
• Dropout Voltage: 0.5V typical at I_OUT = 1A (1V max over temperature)
• Quiescent Current:
  • 30 mA typical at I_OUT = 1A, V_IN-V_OUT = 5V
  • 10 mA typical at I_OUT = 100 mA
• Output Noise Voltage: 100 μV RMS (10Hz to 100kHz)
• Ripple Rejection: 60 dB typical at 120Hz
• Short Circuit Current: 2.2A typical
• Thermal Resistance (Junction-to-Ambient): 65°C/W (TO-220 package)

Package Information

The LM2941C is available in several industry-standard packages to accommodate different application requirements:

TO-220 Package (5-Lead)

• Package Type: Through-hole, tabbed
• Dimensions: 10.16mm x 8.89mm x 4.57mm (body)
• Lead Pitch: 2.54mm
• Thermal Characteristics: Excellent heat dissipation capability
• Mounting: Requires heatsink for high current applications

TO-263 Surface Mount Package

• Package Type: Surface mount D²PAK
• Dimensions: 10.28mm x 9.65mm x 4.57mm
• Thermal Pad: Large exposed pad for enhanced heat dissipation
• Recommended PCB Layout: Adequate copper area for thermal management

Ordering Information

• LM2941CT-5.0: Fixed 5V output in TO-220 package
• LM2941CT-12: Fixed 12V output in TO-220 package
• LM2941CSX-5.0: Fixed 5V output in TO-263 package
• LM2941CAdj: Adjustable version (5V to 20V)

Design Considerations

Input Capacitor Selection

A 10μF or greater aluminum electrolytic capacitor is recommended at the input to ensure stable operation and provide local energy storage. For automotive applications or environments with significant line transients, larger values may be required.

Output Capacitor Requirements

The LM2941C is designed to be stable with low-ESR capacitors. A minimum of 10μF aluminum electrolytic or 4.7μF tantalum capacitor is recommended. For best transient response, place the output capacitor as close as possible to the regulator's output and ground pins.

Thermal Management

For continuous operation at full load current (1A), proper thermal design is essential:

• Use adequate PCB copper area for surface mount packages
• Consider heatsinks for TO-220 packages in high ambient temperatures
• Ensure proper airflow in enclosed systems
• Monitor junction temperature in extreme environments

Adjustable Output Configuration

For adjustable versions, the output voltage is set using a resistor divider network:

• V_OUT = 1.275V × (1 + R2/R1)
• Recommended R1 value: 1kΩ to 5kΩ
• Low-tolerance resistors (1% or better) recommended for precise output

Conclusion

The LM2941C represents a robust, high-performance solution for voltage regulation in demanding applications. Its combination of low dropout voltage, current handling capability, and comprehensive protection features