Features: *3.3V, 5V, 12V, and adjustable output versions
* Adjustable version output voltage range, 1.2V to 37V (57V for the HV version)±4% max over line and load conditions
*Available in 8-pin surface mount and DIP-8 package
* Guaranteed 0.5A output current
* Input voltage range up to 60V
* Requires only 4 external components
* 150 kHz fixed frequency internal oscillator
* TTL Shutdown capability
* Low power standby mode, IQ typically 85 A
* High Efficiency
* Uses readily available standard inductors
* Thermal shutdown and current limit protectionApplicationSimple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to Negative convertorPinout
SpecificationsIf Military/Aerospace specified devices are required,pleasecontacttheNationalSemiconductorSalesOffice/Distributors for availability and specifications.
Maximum Supply Voltage
LM2594 45V
LM2594HV 60V
ON /OFF Pin Input Voltage -0.3 V +25V
Feedback Pin Voltage -0.3 V +25V
Output Voltage to Ground
(Steady State) -1V
Power Dissipation Internally limited
Storage Temperature Range -65 to +150
Human Body Model (Note 2) 2 kV
Lead Temperature
M8 Package
Vapor Phase (60 sec.)
Infrared (15 sec.)+215
N Package (Soldering, 10 sec.)+220
Maximum Junction Temperature+260
ESD Susceptibility +150
DescriptionThe LM2594/LM2594HV series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 0.5A load with excellent line and load regulation. These de-vices are available in fixed output voltages of 3.3V, 5V, 12V,and an adjustable output version, and are packaged in a 8-lead DIP and a 8-lead surface mount package.
Requiringaminimumnumberofexternalcomponents,these regulators are simple to use and feature internal frequency compensation+, a fixed-frequency oscillator, and improved line and load regulation specifications.
The LM2594/LM2594HV series operates at a switching fre-quency of 150 kHz thus allowing smaller sized filter compo-nents than what would be needed with lower frequency switching regulators. Because of its high efficiency, the cop-per traces on the printed circuit board are normally the only heat sinking needed.
A standard series of inductors (both through hole and sur-face mount types) are available from several different manu-facturers optimized for use with the LM2594/LM2594HV se-ries. This feature greatly simplifies the design of switch-mode power supplies.
Other features include a guaranteed ±4% tolerance on out-put voltage under all conditions of input voltage and output load conditions, and ±15% on the oscillator frequency. Ex-ternal shutdown is included, featuring typically 85 A 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.
The LM2594HV is for applications requiring an input voltag up to 60V.
LM2594 Data Sheet
