Product Overview
Adjustable 1.23V-37V Buck Switching Converter IC in 5-Pin TO-220
Condition
Unused new old stock (NOS). Straight 5-pin through-hole leads with clean metal mounting tab. Markings legible: National Semiconductor logo, LM2575T, -ADJ P+. Sold each.
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Product Overview
Designed for efficient step-down voltage conversion, the National Semiconductor LM2575T-ADJ provides an adjustable DC output from 1.23V to 37V at up to 1.0A. Operating at an internal switching frequency of 52 kHz, this monolithic regulator requires minimal external components to replace inefficient linear regulators. Built-in protection includes cycle-by-cycle current limiting and thermal shutdown for robust circuit reliability.
Key Features
- Output Voltage Range: Adjustable from 1.23V to 37V
- Maximum Output Current: 1.0A continuous load
- Maximum Input Voltage: 40V
- Internal Switching Frequency: 52 kHz
- Package: 5-pin TO-220 with metal mounting tab
- Protection: Cycle-by-cycle current limiting and thermal shutdown
- Control: Pin 5 TTL-compatible ON/OFF control line
Applications
- Replacing hot linear regulators in bench supplies and embedded projects without adding bulky heatsinks.
- Stepping down 24V or 12V industrial control rails to power 5V or 3.3V microcontrollers and logic boards.
- Building custom adjustable buck converters for maker electronics, robotics, and battery-powered field gear.
- Servicing legacy industrial control equipment originally designed around National Semiconductor Simple Switcher ICs.
Frequently Asked Questions
What is the pinout for this 5-pin TO-220 package?
Pin 1 is Voltage Input (VIN), Pin 2 is Output, Pin 3 is Ground, Pin 4 is Feedback, and Pin 5 is ON/OFF control.
What external components are required for a working buck circuit?
Operation requires an input bypass capacitor, a Schottky catch diode, a buck inductor, an output filter capacitor, and two programming resistors to establish the desired feedback voltage divider.
How does the -ADJ version differ from fixed-output LM2575 regulators?
The -ADJ version uses Pin 4 as an external feedback sense input configured with a two-resistor divider, allowing custom output adjustments between 1.23V and 37V rather than relying on fixed internal resistance ladders. More pieces cost less each - the price-break table on this page shows what each quantity costs.
Before integrated switchers came along, dropping 24 volts down to five meant bolting on a heavy slab of aluminum and hoping the linear regulator survived the heat. This five-pin TO-220 does the heavy lifting quietly so your project stays cool.
