The LM117HP+ is an adjustable 3-terminal positive voltage regulator manufactured by National Semiconductor, now Texas Instruments (TI). It is capable of supplying more than 1.5A of output current over an output voltage range of 1.2V to 37V. It is extremely easy to use and requires only two external resistors to set the output voltage.

Applications

• Adjustable Power Supplies
• Battery Chargers
• Current Regulators
• Bench Power Supplies
• Microprocessor Power Supplies
• Post Regulation for Switching Supplies

Features

• Adjustable Output Voltage: 1.2V to 37V
• Guaranteed 1.5A Output Current
• Internal Thermal Overload Protection
• Internal Short-Circuit Current Limiting
• Output Transistor Safe-Area Compensation
• Floating Operation for High Voltage Applications
• Standard 3-Terminal Transistor Package

Benefits

• Simplified Power Supply Design: Requires only two external resistors for voltage adjustment.
• High Output Current Capability: Can supply power to a wide range of loads.
• Robust Protection Features: Protects the regulator and the load from damage.
• Wide Input Voltage Range: Can operate from a variety of input sources.
• Cost-Effective Solution: Provides a simple and inexpensive way to regulate voltage.

Additional Details

The LM117HP+ is typically packaged in a TO-220 package. The '+' symbol likely refers to RoHS compliance. The output voltage is determined by the formula: Vout = 1.25V * (1 + (R2/R1)), where R1 and R2 are the external resistors connected to the adjust pin. It's important to select appropriate resistor values to achieve the desired output voltage and ensure stability. The datasheet specifies the recommended range of resistor values. The input voltage must be higher than the desired output voltage by a minimum of 3V. Heat sinking may be required for applications with high input-output voltage differential and high output current to prevent overheating. Internal protection circuits limit the output current and protect the device from thermal overload. Detailed specifications including maximum input voltage, operating temperature range, thermal resistance, and ripple rejection are available in the datasheet.