LM2575 52kHz Simple Buck Regulator General Description

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LM2575 52kHz Simple Buck Regulator General Description

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LM2575
LM2575
52kHz Simple Buck Regulator
General Description
LM2575 series monolithic integrated circuits provide active functions step-down (buck) switching regulator. Fixed versions available with 3.3V, 12V, fixed output. Adjustable versions have output voltage range from 1.23V 37V. Both versions capable driving load with excellent line load regulation. These regulators simple because they require minimum number external components include internal frequency compensation fixed-frequency oscillator. LM2575 series offers high efficiency replacement popular three-terminal adjustable linear regulators. substantially reduces size heat sink, many cases heat sink required. standard series inductors available from several different manufacturers ideal with LM2575 series. This feature greatly simplifies design switch-mode power supplies. feedback voltage guaranteed tolerance adjustable versions, output voltage guaranteed fixed versions, within specified input voltages output load conditions. oscillator frequency guaranteed ±10%. External shutdown included, featuring less than 200µA standby current. output switch includes cycle-bycycle current limiting thermal shutdown full protection under fault conditions.
Features
3.3V, 12V, adjustable output versions Voltage over specified line load conditions: Fixed version: max. output voltage Adjustable version: max. feedback voltage Guaranteed output current Wide input voltage range: Wide output voltage range 1.23V Requires only external components 52kHz fixed frequency internal oscillator power standby mode typically 200µA efficiency (adjustable version typically 80%) Uses readily available standard inductors Thermal shutdown current limit protection 100% electrical thermal limit burn-in
Applications
Simple high-efficiency step-down (buck) regulator Efficient pre-regulator linear regulators On-card switching regulators Positive negative converter (inverting Buck-Boost) Isolated Flyback Converter using minimum number external components Negative Boost Converter
Typical Applications
7V-40V Unregulated Input
+VIN 100µF
LM2575-5.0 Output 330µH On/Off 1N5822
Feedback
+5V, Regulated Output COUT 330µF
7V-40V Unregulated Input
LM2575
Feedback
+VIN 100µF
On/Off
Output 330µH 1N5822
+5V, Regulated Output COUT 330µF 3.09k
Note: numbers TO-220 Package
Note: numbers TO-220 Package VOUT 1.23
Fixed Regulator Typical Application
Adjustable Regulator Fixed Output Application
August 1999
M2575
LM2575
Ordering Information
Part Number LM2575BN* LM2575-3.3BN LM2575-5.0BN LM2575-12BN LM2575BWM* LM2575-3.3BWM LM2575-5.0BWM LM2575-12BWM LM2575BT*
Temperature Range -40°C -40°C -40°C -40°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C
Package 16-pin Plastic 16-pin Plastic 16-pin Plastic 16-pin Plastic 24-pin Wide SOIC 24-pin Wide SOIC 24-pin Wide SOIC 24-pin Wide SOIC 5-lead TO-220 5-lead TO-220 5-lead TO-220 5-lead TO-220 5-lead TO-263 5-lead TO-263 5-lead TO-263 5-lead TO-263
LM2575-3.3BT LM2575-5.0BT LM2575-12BT LM2575BU*
LM2575-3.3BU LM2575-5.0BU LM2575-12BU
Adjustable output regulators. Contact factory bent staggered leads option.
Configurations
5-LEAD TO-220
ON/OFF FEEDBACK GROUND OUTPUT
5-LEAD TO-263
ON/OFF FEEDBACK GROUND OUTPUT
24-LEAD SOIC (WM)
16-LEAD
OUTPUT ON/OFF
ON/OFF
OUTPUT OUTPUT
LM2575
August 1999
LM2575
Absolute Maximum Ratings (Note
Maximum Supply Voltage ON/OFF Input Voltage Output Voltage Ground (Steady State) Power Dissipation Storage Temperature Range Minimum Rating 100pF, 1.5k Lead Temperature (soldering, sec.) Maximum Junction Temperature -0.3V +40V Internally Limited -65°C +150°C 260°C 150°C
Operating Ratings
Temperature Range Supply Voltage -40°C +125°C
Electrical Characteristics Specifications with standard typeface 25°C, those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, 12V, ILOAD 200mA.
LM2575 Symbol Parameter Conditions Limit (Note Units (Limits)
SYSTEM PARAMETERS, ADJUSTABLE REGULATORS (Note Test Circuit Figure VOUT Feedback Voltage ILOAD 0.2A VOUT 0.2A ILOAD VOUT 12V, ILOAD VOUT ILOAD 0.2A VOUT 3.3V 0.2A ILOAD VOUT 3.3V 12V, ILOAD ILOAD 0.2A VOUT 0.2A ILOAD VOUT 12V, ILOAD ILOAD 0.2A VOUT 0.2A ILOAD VOUT 25V, ILOAD 1.230 1.217 1.243 1.230 1.193/1.180 1.267/1.280 V(min) V(max) V(min) V(max)
VOUT
Feedback Voltage LM2575 Efficiency
SYSTEM PARAMETERS, 3.3V REGULATORS (Note Test Circuit Figure VOUT Output Voltage 3.234 3.366 3.168/3.135 3.432/3.465 V(min) V(max) V(min) V(max)
VOUT
Output Voltage LM2575-3.3 Efficiency
SYSTEM PARAMETERS, REGULATORS (Note Test Circuit Figure VOUT Output Voltage 4.900 5.100 4.800/4.750 5.200/5.250 V(min) V(max) V(min) V(max)
VOUT
Output Voltage LM2575-5.0 Efficiency
SYSTEM PARAMETERS, REGULATORS (Note Test Circuit Figure VOUT Output Voltage 11.760 12.240 11.520/11.400 12.480/12.600 V(min) V(max) V(min) V(max)
VOUT
Output Voltage LM2575-12 Efficiency
August 1999
M2575
LM2575
Electrical Characteristics (continued)
LM2575 Symbol Parameter Conditions Limit (Note Units (Limits)
DEVICE PARAMETERS, ADJUSTABLE REGULATOR Feedback Bias Current VOUT 100/500
DEVICE PARAMETERS, FIXED ADJUSTABLE REGULATORS Oscillator Frequency 47/42 58/63 Saturation Voltage Duty Cycle (ON) Current Limit IOUT (Note (Note Peak Current, (Note 1.2/1.4 1.7/1.3 3.0/3.2 Standby Quiescent Current Thermal Resistance ON/OFF (OFF) Package, Junction Ambient (Note Package, Junction Ambient (Note Package, Junction Case Package, Junction Ambient (Note Package, Junction Amb. (Note (min) (max) V(max) %(min) A(min) A(max) mA(max) mA(max) mA(max) µA(max) °C/W
VSAT
Output Leakage Current
40V, (Note (Note
Output Output Output
ISTBY
Quiescent Current
(Note
LM2575
August 1999
LM2575
LM2575 Symbol Parameter Conditions Limit (Note
Units (Limits)
ON/OFF CONTROL, FIXED ADJUSTABLE REGULATORS Test Circuit Figure
Note
ON/OFF Logic Input Level /OFF Logic Current
VOUT VOUT /OFF (OFF) ON/OFF (ON)
2.2/2.4 1.0/0.8
V(min) V(max) µA(max) µA(max)
0.01
Absolute Maximum Rating indicate limits beyond which damage device occur. Operating Ratings indicate conditions which device intended functional, guarantee specific performance limits. guaranteed specifications test conditions, Electrical Characteristics. limits guaranteed room temperature (standard type face) temperature extremes (bold type face) room temperature limits 100% production tested. limits temperature extreme guaranteed testing. External components such catch diode, inductor, input output capacitors affect switching regulator system performance. When LM2575/LM1575 used shown Figure test circuit, system performance will shown system parameters section Electrical Characteristics. Output (pin sourcing current. diode, inductor capacitor connected output. Feedback (pin removed from output connected Feedback (pin removed from output connected force output transistor OFF. Junction ambient thermal resistance external heat sink) 5-lead TO-220 package mounted vertically, with 1/2" leads socket, board with minimum copper area. Junction ambient thermal resistance external heat sink) 5-lead TO-220 package mounted vertically, with 1/4" leads soldered board containing approximately square inches copper area surrounding leads. Junction ambient thermal resistance with approximately square inch board copper surrounding leads. Additional copper will lower thermal resistance further.
Note Note
Note Note Note Note Note Note
Typical Performance Characteristics
Normalized Feedback Voltage*
NORMALIZED FEEDBACK VOLTAGE (mV)
Feedback Voltage Duty Cycle*
FEEDBACK VOLTAGE CHANGE (mV)
ILOAD 200mA Normalized 25°C
ILOAD
JUNCTION TEMPERATURE (°C)
DUTY CYCLE
Adjustable version only
August 1999
M2575
LM2575
(Circuit Figure
Typical Performance Characteristics (continued)
Supply Current Duty Cycle
Supply Current
SUPPLY CURRENT (mA)
Standby Quiescent Current
STANDBY QUIESCENT CURRENT (µA)
SUPPLY CURRENT (mA)
Measured Ground 25°C VOUT
20.0 17.5 15.0 12.5 10.0 from ILOAD
VON/OFF
ILOAD
JUNCTION TEMPERATURE (°C)
INPUT VOLTAGE
DUTY CYCLE
Current Limit
SATURATION VOLTAGE OUTPUT CURRENT
Switch Saturation Voltage
-55°C -40°C 25°C
EFFICIENCY
Efficiency
VOUT
INPUT VOLTAGE
VOUT
125°C 150°C
SWITCH CURRENT
JUNCTION TEMPERATURE (°C)
Minimum Operating Voltage
NORMALIZED FEEDBACK VOLTAGE (mV)
Line Regulation
Normalized VOUT ILOAD 500mA
STANDBY QUIESCENT CURRENT (µA)
Feedback Current
-100
INPUT VOLTAGE
VOUT 1.23V ILOAD
JUNCTION TEMPERATURE (°C)
INPUT VOLTAGE
JUNCTION TEMPERATURE (°C)
Normalized Output Voltage
OUTPUT VOLTAGE CHANGE (mV)
Oscillator Frequency
NORMALIZED FREQUENCY
Dropout Voltage
INPUT-OUTPUT DIFFERENTIAL
ILOAD 200mA Normalized 25°C
Normalized 25°C ILOAD
VOUT
ILOAD
-100
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
LM2575
August 1999
LM2575
Typical Performance Characteristics (Circuit Figure
Load Transient Response Switching Waveforms
+100mV Output Voltage Change -100mV
1.0A Output Current 0.5A 100µS/div.
Output voltage 10V/div Output current 1A/div Inductor current 0.5A/div Output ripple voltage mV/div. coupled
Test Circuits Layout Guidelines
FEEDBACK +VIN
Horizontal Time Base: 5µs/div
LM2575
UNREGULATED INPUT ON/OFF
OUTPUT
MBR360
VOUT 5.00V 470µF
100µF, Aluminum Electrolytic 470µF, Aluminum Electrolytic Schottky, MBR360 330µH, 415-0926 (AIE) 0.01% 3.065k, 0.01% 5-pin TO-220 socket-2936 (Loranger Mfg. Co.) 4-pin TO-3 socket-8112-AG7 (Augat Inc.)
FEEDBACK +VIN
LM2575-5.0
UNREGULATED INPUT ON/OFF
OUTPUT
MBR360
VOUT 5.00V 220µF
100µF, Aluminum Electrolytic 330µF, Aluminum Electrolytic Schottky, MBR360 330µH, 415-0926 (AIE) 5-pin TO-220 socket-2936 (Loranger Mfg. Co.) 4-pin TO-3 socket-8112-AG7 (Augat Inc.)
Note: numbers TO-220 Package
Figure
switching regulator, layout very important. Rapidly switching currents associated with wiring inductance generate voltage transients which cause problems. minimal stray inductance ground loops, length leads indicated heavy lines should kept short possible. Single-point grounding indicated) ground plane construction should used best results.
Block Diagrams
FEEDBACK
3.1k
INTERNAL REGULATOR
ON/OFF
ON/OFF
INTERNAL REGULATOR
ON/OFF
ON/OFF
FIXED GAIN ERROR
FIXED GAIN ERROR COMPARATOR SWITCH FEEDBACK
1.0k
COMPARATOR
SWITCH
DRIVER
DRIVER
1.23V BAND-GAP REFERENCE
OUTPUT 1.23V BAND-GAP REFERENCE
OUTPUT
OSCILLATOR
RESET
THERMAL SHUTDOWN
CURRENT LIMIT
OSCILLATOR
RESET
THERMAL SHUTDOWN
CURRENT LIMIT
Note: numbers TO-220 package
Fixed Regulator August 1999
Adjustable Regulator M2575

LM2575 52kHz Simple Buck Regulator General Description

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