A range of of regulators that are monolithic integrated circuits, which provide all the active functions for a step-down (buck) switching regulator, have been introduced by Texas Instruments with the the LM2596 series. The series is capable of driving a 3A load with line and load regulation. These devices are available in fixed output voltages of 3.3, 5, and 12V, and an adjustable output version.
Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation, and a fixed-frequency oscillator.
The LM2596 series operates at a switching frequency of 150kHz, thus allowing smaller sized filter components than what would be required with lower frequency switching regulators. Available in a standard seven pin TO-220 package with several different lead bend options, and a seven pin TO-263 surface mount package.
A standard series of inductors are available from several different manufacturers optimised for use with the LM2596 series. This feature greatly simplifies the design of switch-mode power supplies.
Other features include a ±4% tolerance on output voltage under specified input voltage and output load conditions, and ±15% on the oscillator frequency. External shutdown is included, featuring typically 80 µA standby current. Self-protection features include a two stage frequency reducing current limit for the output switch and an over temperature shutdown for complete protection under fault conditions.
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