NJM79L08UA: In-Depth Technical Analysis of the -8V Negative Linear Voltage Regulator

Product Introduction and Manufacturer Background

The NJM79L08UA represents a precision-engineered linear voltage regulator IC developed by Nisshinbo Micro Devices Inc., a Japanese semiconductor company renowned for its analog and power management solutions. This negative voltage regulator, though now classified as obsolete, continues to serve critical functions in electronic systems requiring stable -8V power rails.

Detailed Technical Specifications

Comprehensive Electrical Characteristics

• Output Voltage: Fixed -8V 4% accuracy
• Maximum Input Voltage: -35V (absolute maximum rating)
• Recommended Input Voltage Range: -10.5V to -30V
• Output Current Capacity: 100mA continuous
• Dropout Voltage: 1.7V typical at full load
• Line Regulation: 15mV typical (Vin = -11V to -30V)
• Load Regulation: 30mV typical (Iout = 1mA to 100mA)
• Ripple Rejection: 68dB at 120Hz (improves at lower frequencies)
• Thermal Resistance: 125 C/W (junction-to-ambient in SOT-89)

Advanced Package Information

The device comes in a SOT-89-3 (TO-243AA) surface-mount package with the following mechanical dimensions:

• Package Height: 1.6mm max
• Lead Pitch: 1.5mm
• Package Width: 4.5mm
• Thermal Pad Area: 2.5mm 2.5mm

Functional Block Diagram and Pin Configuration

Pinout Details

1. Input Pin (V_IN): Connects to the unregulated negative input voltage
2. Ground Pin (GND): System common reference
3. Output Pin (V_OUT): Delivers regulated -8V output

Internal Architecture

The IC incorporates:

• Bandgap reference circuit
• Error amplifier with temperature compensation
• Series pass transistor
• Overcurrent protection circuitry
• Thermal shutdown module

Application Circuits and Design Guidelines

Basic Implementation

For most applications, only two capacitors are required:

• Input capacitor: 0.33 F ceramic (placed close to V_IN pin)
• Output capacitor: 0.1 F ceramic (placed close to V_OUT pin)

Advanced Configurations

The NJM79L08UA can be used in:

• Dual Power Supplies: Combined with positive regulators for op-amp circuits
• Noise-Sensitive Applications: Additional LC filtering for improved PSRR
• High-Current Solutions: External pass transistor configurations

Common Applications and Industry Uses

• Audio Equipment: Negative rail for op-amps in mixers and preamps
• Test and Measurement: Precision reference circuits
• Industrial Controls: Sensor interface power supplies
• Legacy Systems: Maintenance of older electronic equipment
• Educational Projects: Demonstrating negative voltage regulation

Alternative Components and Cross-Reference

Direct Replacements

• LM79L08ACZ (National Semiconductor)
• MC79L08ACP (ON Semiconductor)
• UA79L08ACLP (Texas Instruments)

Modern Alternatives

• LDO Negative Regulators with better efficiency
• Switching Regulator Modules for higher current needs
• Programmable Power Management ICs

Reliability and Compliance Information

• Operating Temperature Range: -40 C to +85 C
• Storage Temperature Range: -65 C to +150 C
• ESD Protection: 2kV HBM (Human Body Model)
• RoHS Compliance: Original version contained lead (Pb)

Purchasing Considerations

When sourcing NJM79L08UA:

• Verify authenticity to avoid counterfeit parts
• Check date codes for remaining shelf life
• Consider minimum order quantities
• Evaluate alternative solutions for new designs

Technical Support Resources

• Original Datasheet PDF availability
• Application notes from Nisshinbo
• SPICE models for circuit simulation
• Evaluation board design files

Conclusion and Final Recommendations

The NJM79L08UA remains a technically sound solution for -8V regulation despite its obsolete status. Engineers maintaining legacy systems or requiring its specific characteristics will find it delivers reliable performance when properly implemented. For new designs, we recommend evaluating modern alternatives unless specific compatibility requirements exist.

Our inventory includes genuine NJM79L08UA regulators with full traceability. Contact our technical sales team for volume pricing, samples, or assistance with alternative component selection.