The LM2597xx series of regulators are monolithic integrated circuits that provide all the
active functions for a step-down (buck) switching regulator, capable of driving a 0.5-A load with
excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V,
5 V, 12 V, and an adjustable output version, and are packaged in an 8-pin PDIP and an 8-pin
This series of switching regulators is similar to the LM2594 series, with additional
supervisory and performance features added.
Requiring a minimum number of external components, these regulators are simple to use and
include internal frequency compensation, improved line and load specifications, fixed-frequency
oscillator, Shutdown/Soft-start, error flag delay, and error flag
The LM2597xx series operates at a switching frequency of 150-kHz, thus allowing
smaller-sized filter components than what would be required with lower-frequency switching
regulators. Because of its high efficiency, the copper traces on the printed-circuit board are
normally the only heat sinking required.
A standard series of inductors (both through-hole and surface-mount types) are available
from several different manufacturers optimized for use with the LM2597xx series. This feature
greatly simplifies the design of switch-mode power supplies.
Other features include a specified ±4% tolerance on output voltage under all conditions
of input voltage and output load conditions, and ±15% on the oscillator frequency. External
shutdown is included, featuring typically 85-µA standby current. Self protection features include a
two stage current limit for the output switch and an overtemperature shutdown for complete
protection under fault conditions.
The LM2597HV is for use in applications requiring and input voltage up to 60 V.