LM723CH

LM723CH Voltage Regulator Technical Summary

Overview

The LM723CH is a highly versatile voltage regulator IC designed primarily for series regulator applications. Manufactured by Texas Instruments and other semiconductor companies, this component provides a stable voltage reference and error amplifier, making it suitable for both linear and switching regulator designs. The device can operate with input voltages up to 40V and delivers output currents up to 150mA without requiring external pass transistors. For higher current applications, external transistors can be added to scale the output current to 10A or more.

Key to its design is the extremely low standby current drain, making it energy-efficient for battery-powered applications. The LM723CH also includes built-in features for linear or foldback current limiting, providing robust protection against overload conditions. Its flexible architecture allows it to be configured as a positive or negative voltage regulator, shunt regulator, or current regulator.

Features

• Wide Input Voltage Range: Operates from 9.5V to 40V, making it suitable for various power supply designs.
• Adjustable Output Voltage: Can be set from 2V to 37V using external resistors.
• High Output Current Capability: Delivers up to 150mA without an external pass transistor; supports >10A with external transistors.
• Low Standby Current: Typically 2.5mA, enhancing efficiency in low-power applications.
• Current Limiting: Supports both linear and foldback current limiting for overload protection.
• Temperature Stability: Features a built-in temperature-compensated voltage reference.
• Short-Circuit Protection: Includes internal circuitry to prevent damage during fault conditions.
• Wide Operating Temperature Range: -55°C to +125°C (military-grade versions available).

Applications

The LM723CH is widely used in power supply designs due to its flexibility and reliability. Common applications include:

• Linear Voltage Regulators: Fixed or adjustable output voltage supplies for industrial and consumer electronics.
• Switching Regulators: Can be configured in buck or boost topologies with additional components.
• Current Regulators: Precision current sources for battery charging or LED drivers.
• Shunt Regulators: Used in overvoltage protection circuits or as a voltage clamp.
• Laboratory Power Supplies: Adjustable benchtop power supplies with programmable voltage and current limits.
• Automotive Electronics: Voltage stabilization in vehicle power systems.
• Telecommunications: Power management in communication infrastructure.

Electrical Characteristics

The following table summarizes the key electrical specifications of the LM723CH under typical operating conditions (25°C, V_IN = 15V unless otherwise noted):

• Reference Voltage (V_REF): 7.15V (min) – 7.25V (typ) – 7.35V (max)
• Line Regulation: 0.01% / V (typ)
• Load Regulation: 0.04% / mA (typ)
• Output Voltage Range: 2V to 37V (adjustable)
• Output Current (Internal): 150mA (max)
• Standby Current: 2.5mA (typ)
• Input Voltage Range: 9.5V to 40V
• Current Limit Threshold: Adjustable via external resistor
• Operating Temperature Range: 0°C to +70°C (commercial), -55°C to +125°C (military)

Package Information

The LM723CH is available in multiple package options to accommodate different PCB layouts and thermal requirements:

• TO-99 Metal Can (LM723CH):
  • 8-pin round metal package
  • Excellent thermal performance
  • Dimensions: 9.08mm diameter, 5.2mm height
• PDIP-14 (Plastic Dual In-Line Package):
  • 14-pin plastic DIP
  • Widely used for prototyping and breadboarding
  • Dimensions: 19.3mm x 6.35mm
• SOIC-14 (Surface-Mount Package):
  • 14-pin small outline IC
  • Ideal for space-constrained designs
  • Dimensions: 8.65mm x 3.9mm

Design Considerations

When implementing the LM723CH in a circuit, consider the following guidelines:

• External Pass Transistors: For high-current applications (>150mA), use NPN or PNP transistors with adequate heat sinking.
• Current Sensing Resistor: Select a low-value, high-precision resistor for accurate current limiting.
• Feedback Network: Use stable, low-temperature-coefficient resistors for voltage adjustment.
• Decoupling Capacitors: Place 0.1µF ceramic capacitors near the V_IN and V_REF pins to minimize noise.
• Thermal Management: Ensure proper heat dissipation, especially in high-current or high-ambient-temperature environments.

Conclusion

The LM723CH remains a popular choice for engineers designing custom voltage regulators due to its versatility, robustness, and ease of use. Its ability to support a wide range of configurations—from low-power battery-operated devices to high-current industrial power supplies—makes it a staple in analog power design. With proper external components, the LM723CH can deliver precision voltage regulation, current limiting, and thermal protection, ensuring reliable performance across diverse applications.