Features: *3.3V, 5V, 12V, 15V, and adjustable output versions
* Adjustable version output voltage range, 1.23V to 37V (57V for HV version) ±4% max over line and load conditions
* Guaranteed 0.5A output current
* Wide input voltage range, 40V, up to 60V for HV version
* Requires only 4 external components
* 52 kHz fixed frequency internal oscillator
* TTL shutdown capability, low power standby mode
* 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 converter (Buck-Boost)Pinout
SpecificationsIf Military/Aerospace specified devices are required,pleasecontacttheNationalSemiconductorSalesOffice/Distributors for availability and specifications.
LM2574 45V
LM2574HV 63V
ON /OFF Pin Input Voltage -0.3V V +VIN
Output Voltage to Ground
(Steady State) -1V
Minimum ESD Rating
(C = 100 pF, R = 1.5 k) 2kV
Storage Temperature Range -65 to +150
Lead Temperature
(Soldering, 10 seconds) 260
Maximum Junction Temperature 150
Power Dissipation Internally Limited
| Output Current |
500 mA |
| Input Min Voltage |
4 Volt |
| Input Max Voltage |
40 Volt |
| Output Min |
3.3, 1.23, 12, 5 Volt |
| Output Max |
3.3, 37, 12, 5 Volt |
| Frequency Min |
52 kHz |
| Frequency Max |
52 kHz |
| Efficiency (peak) |
77, 88, 72 % |
| On/Off Pin |
Yes |
| Error Flag |
No |
| SoftStart |
No |
| Sync Pin |
No |
| Inverting |
Yes |
| Flyback |
No |
| RegType |
Switching Regulator |
| Temperature Min |
-40 deg C |
| Temperature Max |
125 deg C |
| Adjustable Output |
Yes, No |
| Adj Switch Frequency |
No |
| PWM Mode |
Voltage |
| Topology |
Buck |
| Special Features |
SIMPLE SWITCHER regulator |
| Step-Down |
Yes |
| Multiple Output Capability |
No |
| Output Power |
Undefined Watt |
| Output Voltage |
3.3, Undefined, 12, 5 Volt |
| Output Range |
5V, 12V, 1.23V to 37V, 3.3V |
| Switching Frequency |
52 kHz |
| Regulator Family |
SIMPLE SWITCHER |
| AEC Q-100 Automotive Grade |
Undefined |
| Synchronous Rectification |
No |
| View Using Catalog |
DescriptionThe LM2574 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 devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an adjustable output version.
Requiringaminimumnumberofexternalcomponents,these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator.
The LM2574 series offers a high-efficiency replacement for popular three-terminal linear regulators. Because of its high efficiency, the copper traces on the printed circuit board are normally the only heat sinking needed.
A standard series of inductors optimized for use with the LM2574 are available from several different manufacturers.This feature greatly simplifies the design of switch-mode power supplies.
Other features include a guaranteed ±4% tolerance on out-put voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External shutdown is included, featuring 50 A (typical) standby cur-rent. The output switch includes cycle-by-cycle current limit-ing, as well as thermal shutdown for full protection under fault conditions.
LM2574 Data Sheet
