LM78LXX Series Three-Terminal Positive Voltage Regulator

Overview

The LM78LXX series is a family of three-terminal positive voltage regulators designed to provide fixed output voltages for a wide range of applications. These regulators offer significant improvements over traditional zener diode/resistor combinations, delivering superior output impedance and lower quiescent current. The LM78LXX is particularly useful for on-card regulation, eliminating the challenges associated with single-point regulation in distributed power systems.

Available in multiple voltage options, this regulator series finds applications in logic systems, instrumentation, HiFi audio equipment, and other electronic systems requiring stable voltage regulation. The device incorporates several protection features including thermal overload protection, output transistor safe area protection, and internal short-circuit current limiting.

Key Features

• Output voltage tolerances of ±5% (LM78LXXAC) over operating temperature range
• Stable 100 mA output current capability
• Comprehensive protection features:
  • Internal thermal overload protection
  • Output transistor safe area protection
  • Internal short circuit current limiting
• Available in multiple package options:
  • Plastic TO-92
  • Metal TO-39
  • Plastic SO-8 low profile
• No external components required for basic operation
• Multiple fixed output voltage options:
  • 5.0V
  • 6.2V
  • 8.2V
  • 9.0V
  • 12V
  • 15V

Applications

The LM78LXX series is versatile enough for use in numerous electronic applications:

• Local voltage regulation for logic circuits and microprocessor systems
• Power supply regulation in test and measurement instrumentation
• Voltage stabilization in HiFi audio equipment
• On-card regulation for distributed power systems
• Replacement for zener diode/resistor combinations
• Battery-powered device regulation
• Consumer electronics power management

Electrical Characteristics

Absolute Maximum Ratings

Note 1: If Military/Aerospace specified devices are required, please contact the manufacturer for appropriate specifications.

• Input Voltage: 35V (for 5V-15V versions)
• Power Dissipation: Internally Limited
• Operating Junction Temperature Range:
  • Commercial: 0°C to +125°C
  • Industrial: -40°C to +125°C
• Storage Temperature Range: -65°C to +150°C
• Lead Temperature (Soldering, 10 seconds): 260°C

Electrical Specifications

All specifications are typical at 25°C unless otherwise noted.

• Output Voltage Tolerance: ±5% over full temperature range
• Line Regulation: 0.03%/V (typical)
• Load Regulation: 0.1%/mA (typical)
• Quiescent Current: 5.5mA (typical)
• Ripple Rejection: 55dB (typical at 120Hz)
• Output Noise Voltage: 40μV (typical, 10Hz to 100kHz)
• Dropout Voltage: 1.7V (maximum at 40mA)
• Short Circuit Current: 230mA (typical)
• Output Impedance: 0.3Ω (typical at 1kHz)

Package Information

Connection Diagrams

• TO-39 Metal Can Package (H):
  • Bottom View Configuration
  • Order Numbers: LM78L05ACH, LM78L12ACH, LM78L15ACH
  • NS Package Number: H03A
• SO-8 Plastic Package (M) - Narrow Body:
  • Top View Configuration
  • Order Numbers: LM78L05ACM, LM78L12ACM, LM78L15ACM
  • NS Package Number: M08A
• TO-92 Plastic Package (Z):
  • Bottom View Configuration
  • Order Numbers: LM78L05ACZ, LM78L09ACZ, LM78L12ACZ, LM78L15ACZ, LM78L62ACZ, LM78L82ACZ
  • NS Package Number: Z03A

Package Dimensions and Characteristics

• TO-39 Metal Can:
  • Package Weight: 0.33 grams (typical)
  • Maximum Height: 5.34mm
  • Lead Length: 12.7mm (minimum)
• SO-8 Plastic:
  • Package Weight: 0.09 grams (typical)
  • Maximum Height: 1.75mm
  • Lead Pitch: 1.27mm
• TO-92 Plastic:
  • Package Weight: 0.19 grams (typical)
  • Maximum Height: 5.2mm
  • Lead Pitch: 2.54mm

Design Considerations

When implementing the LM78LXX in your design, consider the following:

• Input bypass capacitors (0.33μF) are recommended when the regulator is located more than 6 inches from the power supply filter
• Output capacitors (0.1μF) improve transient response but are not required for stability
• Thermal considerations are important - ensure adequate heat dissipation for your application's current requirements
• For applications requiring higher current, consider the standard LM78XX series
• The device is not designed for use as a floating regulator

Reliability and Quality

The LM78LXX series is manufactured with high-reliability processes and meets stringent quality standards:

• ESD protection on all pins
• 100% production testing of key parameters
• High-temperature burn-in available for critical applications
• RoHS compliant versions available