LM2594N ADJ

LM2594N ADJ Technical Summary

Overview

The LM2594N ADJ is a member of the LM2594/LM2594HV series of monolithic integrated circuits designed for step-down (buck) voltage regulation. This adjustable-output regulator is capable of delivering up to 0.5A of load current with superior line and load regulation. The device is engineered for simplicity, requiring minimal external components while offering robust performance in a variety of applications. Available in both 8-lead DIP and 8-lead surface-mount packages, the LM2594N ADJ is ideal for compact and space-constrained designs.

Key Features

• Adjustable Output Voltage: Allows users to set the output voltage via external resistors, providing flexibility for diverse applications.
• High Efficiency: Up to 88% efficiency, reducing power dissipation and improving thermal performance.
• Wide Input Voltage Range: 4.5V to 40V (LM2594) and 4.5V to 60V (LM2594HV), accommodating a broad spectrum of input sources.
• Fixed-Frequency Oscillator: 150 kHz internal oscillator ensures predictable performance and simplifies filtering.
• Excellent Line and Load Regulation: Maintains stable output voltage despite variations in input voltage or load conditions.
• Internal Frequency Compensation: Reduces external component count and simplifies circuit design.
• Thermal Shutdown and Current Limiting: Protects the device from overheating and overcurrent conditions.
• Guaranteed Output Voltage Tolerance: ±4% under all input voltage and load conditions.
• Oscillator Frequency Tolerance: ±15%, ensuring consistent switching behavior.

Applications

The LM2594N ADJ is versatile and suitable for a wide range of applications, including:

• Power Supplies: Used in industrial, automotive, and consumer power supply designs.
• Battery-Powered Systems: Efficiently steps down voltage in portable electronics and battery chargers.
• Embedded Systems: Provides regulated power to microcontrollers, sensors, and communication modules.
• Automotive Electronics: Operates reliably in automotive environments with wide input voltage ranges.
• LED Drivers: Delivers stable voltage for LED lighting applications.
• Distributed Power Systems: Used in point-of-load regulation for larger power distribution networks.

Electrical Characteristics

The following table summarizes the key electrical specifications of the LM2594N ADJ under typical operating conditions (TA = 25°C, unless otherwise noted):

• Input Voltage Range: 4.5V to 40V (LM2594), 4.5V to 60V (LM2594HV)
• Output Voltage Range: Adjustable from 1.23V to 37V (LM2594), 1.23V to 57V (LM2594HV)
• Output Current: Up to 0.5A (continuous)
• Switching Frequency: 150 kHz (typical)
• Efficiency: Up to 88% (depending on input/output conditions)
• Quiescent Current: 5 mA (typical)
• Standby Current: 50 µA (typical when disabled)
• Line Regulation: 0.01%/V (typical)
• Load Regulation: 0.5% (typical)
• Thermal Shutdown Threshold: 150°C (typical)

Package Information

The LM2594N ADJ is available in two package options:

• 8-Lead DIP (PDIP-8):
  • Package Dimensions: 9.81mm x 6.35mm x 3.3mm
  • Pin Pitch: 2.54mm
  • Operating Temperature Range: -40°C to +125°C
• 8-Lead Surface Mount (SOIC-8):
  • Package Dimensions: 4.9mm x 3.9mm x 1.75mm
  • Pin Pitch: 1.27mm
  • Operating Temperature Range: -40°C to +125°C

Typical Application Circuit

A basic adjustable output configuration for the LM2594N ADJ includes the following external components:

• Input Capacitor (C_IN): 100µF electrolytic capacitor to filter input voltage ripple.
• Output Capacitor (C_OUT): 220µF electrolytic capacitor to stabilize the output voltage.
• Feedback Resistors (R1 and R2): Sets the output voltage according to the formula V_OUT = 1.23V × (1 + R2/R1).
• Inductor (L1): 100µH inductor to store and transfer energy during switching cycles.
• Diode (D1): Schottky diode (e.g., 1N5822) for efficient freewheeling during switch-off periods.

Conclusion

The LM2594N ADJ is a highly reliable and efficient step-down switching regulator, offering adjustable output voltage, robust protection features, and ease of use. Its wide input voltage range and compact package options make it suitable for a variety of power supply applications. With its guaranteed performance metrics and minimal external component requirements, the LM2594N ADJ is an excellent choice for designers seeking a versatile and dependable voltage regulator solution.