LM2576

3.0A, 52kHz, Step-Down Switching Regulator FEATURES 3.3V, 5.0V, 12V, 15V, and Adjustable Output Versions Adjustable Version Output Voltage Range, 1.23 to 37V +/- 4% AG10Maximum Over Line and Load Conditions Guaranteed 3.0A Output Current Wide Input Voltage Range Requires Only 4 External Components 52kHz Fixed Frequency Internal Oscillator TTL Shutdown Capability, Low Power Standby Mode High Efficiency Uses Readily Available Standard Inductors Thermal Shutdown and Current Limit Protection Moisture Sensitivity Level 3 LM2576 TO-220 PKG 1 5 TO-220V PKG 1 5 TO-263 PKG Applications Simple High-Efficiency Step-Down(Buck) Regulator Efficient Pre-Regulator for Linear Regulators On-Card Switching Regulators Positive to Negative Converter(Buck-Boost) Negative Step-Up Converters Power Supply for Battery Chargers 1 5 1. Vin 2. Output 3. Ground 4. Feedback 5. On/Off DESCRIPTION The LM2576 series of regulators are monolithic integrated circuits ideally suited for easy and convenient design of a step-down switching regulator(buck converter). All circuits of this series are capable of driving a 3.0A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5.0V,12V, 15V, and an adjustable output version. ORDERING INFORMATION Device LM2576T-X.X LM2576TV-X.X LM2576R Marking LM2576T-X.X LM2576T-X.X LM2576R-X.X Package TO-220 TO-220V TO-263 These regulators were designed to minimize the number of external components to simplify the power supply design. Standard series of inductors optimized for use with the LM2576 are offered by several different inductor manufacturers. Since the LM2576 converter is a switch-mode power supply, its efficiency is significantly higher in comparison with popular three-terminal linear regulators, especially with higher input voltages. In many cases, the power dissipated is so low that no heatsink is required or its size could be reduced dramatically. A standard series of inductors optimized for use with the LM2576 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies. The LM2576 features include a guaranteed +/- 4% tolerance on output voltage within specified input voltages and output load conditions, and +/-10% on the oscillator frequency (+/- 2% over 0oC to 125 oC). External shutdown is included, featuring 80 ㎂(typical) standby current. The output switch includes cycle-bycycle current limiting, as well as thermal shutdown for full protection under fault conditions. 2008 - Ver. 1.0 HTC -1- 3.0A, 52kHz, Step-Down Switching Regulator Typical Application (Fixed Output Voltage Versions) LM2576 Figure 1. Block Diagram and Typical Application ABSOLUTE MAXIMUM RATINGS (Absolute Maximum Ratings indicate limits beyond which damage to the device may occur) Rating Maximum Supply Voltage On/Off Pin Input Voltage Output Voltage to Ground (Steady-State) Power Dissipation TO-220 5Lead Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Case TO-263 5Lead Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Case Storage Temperature Range Minimum ESD Rating(Human Body Model : C=100 pF, R=1.5㏀) Lead Temperature (Soldering,10seconds) Maximum Junction Temperature Symbol Vin PD PθJA PθJC PD PθJA PθJC Tstg TJ Value 45 -0.3V ≤ V ≤ +Vin - 1.0 Internally Limited 65 5.0 Internally Limited 70 5.0 -60 to +150 2.0 260 150 Unit V V V W ℃/W ℃/W W ℃/W ℃/W ℃ kV ℃ ℃ HTC -2- 3.0A, 52kHz, Step-Down Switching Regulator LM2576 OPERATING RATINGS(Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications, see the Electrical Characteristics.) Rating Operating Junction Temperature Range Supply Voltage Symbol TJ Vin Value -40 to +125 40 Unit ℃ V ELECTRICAL CHARACTERISTICS / SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 15) (Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values TJ = 25°C, for min/max values TJ is the operating junction temperature range that applies [Note 2], unless otherwise noted.) Characteristics LM2576-3.3V ([Note 1] Test Circuit Figure 2) Output Voltage (Vin = 12V, ILOAD=0.5A, TJ=25℃) Output Voltage (6.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A TJ=25℃ TJ= -40℃ ~ +125℃ Efficiency (Vin=12V, ILOAD=3.0A) LM2576-5.0V ([Note 1] Test Circuit Figure 2) Output Voltage (Vin = 12V, ILOAD=0.5A, TJ=25℃) Output Voltage (8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A TJ=25℃ TJ= -40℃ ~ +125℃ Efficiency (Vin=12V, ILOAD=3.0A) LM2576-12V ([Note 1] Test Circuit Figure 2) Output Voltage (Vin = 25V, ILOAD=0.5A, TJ=25℃) Output Voltage (15V≤Vin≤40V, 0.5A≤ILOAD≤3.0A TJ=25℃ TJ= -40℃ ~ +125℃ Efficiency (Vin=25V, ILOAD=3.0A) LM2576-ADJ ([Note 1] Test Circuit Figure 2) Feedback Voltage (Vin=12V, ILOAD=0.5A, TJ=25℃) Feedback Voltage(8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A, Vout=5.0V) Symbol Min TYP Max Unit Vout Vout η 3.234 3.168 3.135 - 3.3 3.3 75 3.366 3.432 3.465 - V V % Vout Vout η 4.9 4.8 4.75 - 5.0 5.0 77 5.1 5.2 5.25 - V V % Vout Vout η 11.76 11.52 11.4 - 12 12 88 12.24 12.48 12.6 - V V % Vout Vout η 1.217 1.193 1.18 - 1.23 1.23 77 1.243 1.267 1.28 - V V % TJ=25℃ TJ= -40℃ ~ +125℃ Efficiency (Vin=12V, ILOAD=3.0A, Vout=5.0V) 1. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576 is used as shown in the Figure 15 test circuit, system performance will be as shown in system parameters section . 2. Tested junction temperature range for the LM2576: Tlow = –40°C Thigh = +125°C HTC -3- 3.0A, 52kHz, Step-Down Switching Regulator ELECTRICAL CHARACTERISTICS / Device Parameters LM2576 (Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values TJ = 25°C, for min/max values TJ is the operating junction temperature range that applies [Note 2], unless otherwise noted.) Characteristics All Output Voltage Versions Feedback Bias Current (Vout=5.0V [Adjustable Version Only]) Symbol Min TYP Max Unit TJ=25℃ TJ= -40 to +125℃ Oscillator Frequency [Note 3] TJ=25℃ TJ= 0 to +125℃ TJ= -40 to +125℃ Saturation Voltage (Iout=3.0A [note 4]) TJ=25℃ TJ= -40 to +125℃ Max Duty Cycle ("0") [Note 5] Current Limit (Peak Current [Note 3 and 4]) TJ=25℃ TJ= -40 to +125℃ Output Leakage Current [Note 6 and 7], TJ=25℃ Output = 0V Output = -1.0V Quiescent Current [Note 6] TJ=25℃ TJ= -40 to +125℃ Standby Quiescent Current (ON/OFF Pin = 5.0V ("off")) TJ=25℃ TJ= -40 to +125℃ ON/OFF Pin Logic Input Level (Test circuit Figure 15) Vout=0V TJ=25℃ TJ= -40 to +125℃ Vout=Nominal Output Voltage TJ=25℃ TJ= -40 to +125℃ ON/OFF Pin Input Current (Test Circuit Figure 15) ON/OFF Pin = 5.0V (Regulator OFF), TJ=25℃ ON/OFF Pin = 0V (Regulator ON), TJ=25℃ Ib 47 42 94 4.2 3.5 - 25 52 1.5 98 5.8 0.8 6 5 80 - 100 200 58 63 1.8 2 6.9 7.5 50 30 9 11 200 400 nA Fosc kHz Vsat DC ICL V % A IL mA IQ mA ISTBY ㎂ VIH 2.2 2.4 - 1.4 1.2 15 0 1 0.8 30 5.0 V VIL V IIH IIL ㎂ 3. The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which causes the regulated output voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%. 4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to output pin. 5. Feedback (Pin 4) removed from output and connected to 0 V. 6. Feedback (Pin 4) removed from output and connected to +12 V for the Adjustable, 3.3 V, and 5.0V ersions, and +25 V for the 12 V and15 V versions, to force the output transistor “off”. 7. Vin = 40 V. HTC -4- 3.0A, 52kHz, Step-Down Switching Regulator TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 15) LM2576 20 18 IQ, QUIESCENT CURRENT (mA) 16 14 12 10 8 6 4 HTC -5- 3.0A, 52kHz, Step-Down Switching Regulator TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 15) LM2576 HTC -6- 3.0A, 52kHz, Step-Down Switching Regulator TYPICAL PERFORMANCE CHARACTERISTICS LM2576 HTC -7- 3.0A, 52kHz, Step-Down Switching Regulator LM2576 HTC -8- 3.0A, 52kHz, Step-Down Switching Regulator PIN FUNCTION DESCRIPTION Symbol 1 Vin LM2576 Description This pin is the positive input supply for the LM2576 step–down switching 2 3 4 5 regulator.In order to minimize voltage transients and to supply the switching currents needed by the regulator, a suitable input bypass capacitor must be present .(Cin in Figure 1). Output This is the emitter of the internal switch. The saturation voltage Vsat of this output switch is typically 1.5 V. It should be kept in mind that the PCB area connected to this pin should be kept to a minimum in order to minimize coupling to sensitive circuitry. Circuit ground pin. See the information about the printed circuit board layout. Gnd Feedback This pin senses regulated output voltage to complete the feedback loop. The signal is divided by the internal resistor divider network R2, R1 and applied to the non–inverting input of the internal error amplifier. In the Adjustable version of the LM2576 switching regulator this pin is the direct input of the error amplifier and the resistor network R2, R1 is connected externally to allow programming of the output voltage. ON/OFF It allows the switching regulator circuit to be shut down using logic level signals, thus dropping the total input supply current to approximately 80 mA. The threshold voltage is typically 1.4 V. Applying a voltage above this value (up to +Vin) shuts the regulator off. If the voltage applied to this pin is lower than 1.4V or if this pin is left open, the regulator will be in the "on" condition HTC -9- 3.0A, 52kHz, Step-Down Switching Regulator LM2576 HTC - 10 - 3.0A, 52kHz, Step-Down Switching Regulator LM2576 HTC - 11 - 3.0A, 52kHz, Step-Down Switching Regulator LM2576 HTC - 12 - 3.0A, 52kHz, Step-Down Switching Regulator LM2576 HTC - 13 - 3.0A, 52kHz, Step-Down Switching Regulator LM2576 HTC - 14 -