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Details, datasheet, quote on part number:LM2574-5.0BWM
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Datasheet text preview:
LM2574
Micrel
LM2574
52kHz Simple 0.5A Buck Regulator Final Information
General Description
The LM2574 family is a series of easy to use fixed and adjustable switching voltage regulators. The LM2574 contains all of the active circuitry necessary to construct a stepdown (buck) switching regulator and requires a minimum of external components. The LM2574 is available in 3.3V, 5V, and 12V fixed output versions, or an adjustable version with an output voltage range of 1.23V to 37V. Output voltage is guaranteed to ±4% for specified input and load conditions. The LM2574 can supply 0.5A while maintaining excellent line and load regulation. The output switch includes cycle-bycycle current limiting, as well as thermal shutdown for full protection under fault conditions. An external shutdown connection selects operating or standby modes. Standby current is less than 200µA. Heat sinks are generally unnecessary due the regulator's high efficiency. Adequate heat transfer is usually provided by soldering all package pins to a printed circuit board. The LM2574 includes internal frequency compensation and an internal 52kHz fixed frequency oscillator guaranteed to ± 10% of the frequency. Circuits constructed around the LM2574 use a standard series of inductors which are available from several different manufacturers.
Features
· 3.3V, 5V, 12V, and Adjustable Output Versions · Adjustable Version Output 1.23V to 37V ±4% Max. over Line and Load Conditions. · Guaranteed 0.5A Output Current · Wide Input Voltage, up to 40V · Thermal Shutdown and Current Limit Protection · Requires only 4 external Components. · Shutdown Capability (Standby Mode) · Low Power Standby Mode < 200µA Typical · High Efficiency · 52kHz Fixed Frequency Internal Oscillator · Uses Standard Inductors
Applications
· · · · Simple High-efficiency Step-down (Buck) Regulator Efficient Pre-Regulator for Linear Regulators On-card Switching Regulators Positive to Negative Converter (Buck-Boost)
Ordering Information
Part Number LM2574BN LM2574BWM LM2574-3.3BN LM2574-3.3BWM LM2574-5.0BN LM2574-5.0BWM LM2574-12BN LM2574-12BWM Temp. Range 40°C to +85°C 40°C to +85°C 40°C to +85°C 40°C to +85°C 40°C to +85°C 40°C to +85°C 40°C to +85°C 40°C to +85°C Package 8-pin Plastic DIP 14-pin Wide SOIC 8-pin Plastic DIP 14-pin Wide SOIC 8-pin Plastic DIP 14-pin Wide SOIC 8-pin Plastic DIP 14-pin Wide SOIC
Pin Configuration
FB SIG GND ON/OFF PWR GND 1 2 3 4 8 7 6 5 * OUTPUT * VIN
Typical Application
8-pin DIP (N)
40V MAX UNREGULATED DC IN VIN
* * FB SIG GND ON/OFF PWR GND * 1 2 3 4 5 6 7 14 13 12 11 10 9 8 * * OUTPUT * VIN * *
FB LM2574 PWR GND SIG GND OUT ON/ OFF 11DQ05 330µH REGULATED OUTPUT 0.5A
CIN 22µF
COUT 220µF
14-pin SOIC (WM) Figure 1. Fixed Output Regulator Circuit
* NC: solder to printed circuit for maximum heat transfer
Micrel, Inc. · 1849 Fortune Drive · San Jose, CA 95131 · USA · tel + 1 (408) 944-0800 · fax + 1 (408) 944-0970 · http://www.micrel.com
August 1999
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LM2574
LM2574
Micrel
Absolute Maximum Ratings
Maximum Supply Voltage LM2574 ............ 45V OFF Pin Input Voltage ........ 0.3V V VIN Output Voltage to Ground (Steady State) ............ 1V Power Dissipation ... Internally Limited Storage Temperature Range .......... 65°C to +150°C Minimum ESD Rating C = 100pF, R = 1.5k ..... 2kV FB Pin ..... 1kV Lead Temperature (soldering, 10 sec.) ............ 260°C Maximum Junction Temperature ....... 150°C
Operating Ratings
Temperature Range LM2574 .......... 40°C TJ +125°C Supply Voltage LM2574 ............ 40V
Electrical Characteristics
Symbol Parameter
Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply
over full Operating Temperature Range. Unless otherwise specified, Vin = 12V, and ILOAD = 100mA. Condition Min Typ Max Units
SYSTEM PARAMETERS, ADJUSTABLE REGULATORS (Note 3) Test Circuit Figure 2 VOUT VOUT Feedback Voltage Feedback Voltage (LM2574) Efficiency VIN = 12V, ILOAD = 0.1A, VOUT = 5V 0.1A ILOAD 0.5A, 7V VIN 40V, VOUT = 5V VIN = 12V, ILOAD = 0.1A, VOUT = 5V VIN = 12V, ILOAD = 0.1A, VOUT = 3.3V 0.1A ILOAD 0.5A, 4.75V VIN 40V, VOUT = 3.3V VIN = 12V, ILOAD = 0.1A VIN = 12V, ILOAD = 0.1A, VOUT = 5V 0.1A ILOAD 0.5A, 7V VIN 40V, VOUT = 5V VIN = 12V, ILOAD = 0.1A, VOUT = 5V VIN = 25V, ILOAD = 0.1A, VOUT = 12V 0.1A ILOAD 0.5A, 15V VIN 40V, VOUT = 12V VIN = 25V, ILOAD = 0.1A 11.760 11.520 11.400 4.900 4.800 4.750 3.234 3.168 3.135 1.217 1.193 1.180 1.230 1.230 78 1.243 1.267 1.280 V V V %
SYSTEM PARAMETERS, 3.3V REGULATORS (Note 3) Test Circuit Figure 3 VOUT VOUT Output Voltage Output Voltage (LM2574-3.3) Efficiency 3.3 3.3 73 3.366 3.432 3.465 V V V %
SYSTEM PARAMETERS, 5V REGULATORS (Note 3) Test Circuit Figure 3 VOUT VOUT Output Voltage Output Voltage (LM2574-5.0) Efficiency 5.0 5.0 78 5.100 5.200 5.250 V V V %
SYSTEM PARAMETERS, 12V REGULATORS (Note 3) Test Circuit Figure 3 VOUT VOUT Output Voltage Output Voltage (LM2574-12) Efficiency 12 12 88 12.240 12.480 12.600 V V V %
LM2574
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LM2574
Micrel
Electrical Characteristics (continued)
Symbol Parameter Condition Min Typ Max Units DEVICE PARAMETERS, ADJUSTABLE REGULATOR IB Feedback Bias Current VOUT = 5V 50 100 500 nA nA
DEVICE PARAMETERS, FIXED and ADJUSTABLE REGULATORS fo VSAT DC ICL IL IQ ISTBY JA Oscillator Frequency Saturation Voltage Max Duty Cycle (ON) Current Limit Output Leakage Current Quiescent Current Standby Quiescent Current Thermal Resistance Note 8 IOUT = 0.5A, Note 4 Note 5 Peak Current, tON 3µs, Note 4 VIN, Note 6, Output = 0V Note 6, Output = 1V Note 6 ON/OFF Pin = 5V (OFF) N Package, Junction to Ambient, Note 7 WM Package, Junction to Ambient, Note 7 93 0.7 0.65 47 42 52 0.8 98 1.0 1.6 1.8 2 30 10 200 58 63 1.2 1.4 kHz kHz V V % A mA mA µA °C/W °C/W
7.5 5 50 85 100
ON/OFF CONTROL, FIXED and ADJUSTABLE REGULATORS Test Circuit Figures 2, 3 VIH VIL I IH IIL
Note 1
ON/OFF Input Level ON/OFF Input Level ON/OFF Logic Current ON/OFF Logic Current
VOUT = 0V VOUT = 5V ON/OFF = 5V (OFF) ON/OFF = 0V (ON)
2.2 2.4
1.4 1.2 4 0.01 1.0 0.8 30 10
V V V V µA µA
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are guaranteed via testing. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2574 is used as shown in Figure 1 test circuit, system performance will be shown in system parameters section of Electrical Characteristics. Output (pin 2) sourcing current. No diode, inductor, or capacitor connected to input. Feedback (pin 4) removed from output and connected to 0V. Feedback (pin 4) removed from output and connected to 12V to force the output transistor OFF. Junction to ambient thermal resistance with approximately 1 square inches of PC board copper surrounding the leads.
Note 2 Note 3
Note 4 Note 5 Note 6 Note 7
August 1999
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