Product Overview
National Semiconductor LM2575T-ADJ 1A Step-Down Voltage Converter TO-220-5
Condition
Unused new old stock (NOS). Markings legible: LM2575T -ADJ P+ with National Semiconductor logo. Heatsink mounting tab shows a handwritten inventory mark. Straight through-hole leads are clean and intact. Sold each.
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Product Overview
National Semiconductor LM2575T-ADJ is a monolithic step-down switching voltage regulator capable of driving a 1.0A load with high efficiency. Operating at an internal fixed frequency of 52 kHz, this Simple Switcher series device provides an adjustable output range from 1.23V to 37V using an external two-resistor divider. The 5-pin TO-220 through-hole package integrates active protection circuitry, including cycle-by-cycle current limiting and thermal shutdown.
Key Features
- Adjustable output voltage range from 1.23V to 37V set via external feedback resistors
- Delivers up to 1.0A continuous output current
- Wide input operating voltage range from 4.75V to 40V
- Internal 52 kHz fixed-frequency oscillator simplifies inductor selection
- Built-in thermal shutdown and cycle-by-cycle current limit fault protection
- Through-hole 5-lead TO-220 package (TO-220-5) with straight pins
- TTL-compatible ON/OFF control pin for low-power standby operation
Applications
- Stepping down higher-voltage industrial DC rails to regulated 5V or 3.3V logic levels without massive heatsinking
- Replacing inefficient linear regulators on prototyping breadboards and custom maker power supplies
- Powering microcontroller, sensor, and relay boards from wide-range wall adapters or battery banks
- Servicing legacy automation controllers and instrumentation requiring original National Semiconductor Simple Switcher silicon
Frequently Asked Questions
How is the output voltage configured on the LM2575T-ADJ?
The output voltage is set using two external resistors configured as a voltage divider between the regulated output, the feedback pin (Pin 4), and ground. The internal reference regulates to 1.23V across the lower divider resistor.
What is the pinout configuration for this 5-lead TO-220 package?
Pin 1 is input voltage (VIN), Pin 2 is switching output, Pin 3 is ground, Pin 4 is feedback (FB), and Pin 5 is the ON/OFF control input.
How does the LM2575T-ADJ differ from fixed-voltage LM2575 regulators?
Fixed versions like the LM2575T-5.0 integrate an internal resistor network preset for a specific voltage. The -ADJ version routes the error amplifier directly to Pin 4, allowing custom output voltages across the 1.23V to 37V range.
Simple Switchers made efficient buck regulation approachable back when switchmode power usually required discrete oscillator design and tedious tuning. Drop this one in to keep an established rail running cool and steady.
