General description

LM2575 The series stabilizer is a single -chip integrated circuit (BUCK) switching regulator that provides all activation functions, which can drive 1A well -loaded lines And load adjustment. These devices can be used for 3.3V, 5V, 12V, 15V and adjustable output publications. The minimum number of external component regulators is required, including internal frequency compensation and fixed frequency oscillator. The LM2575 series is a popular three -terminal linear regulator. It greatly reduces the size of the radiator and does not require a sink in many cases. A standard series of inductor optimization can be obtained from several different manufacturers. This feature greatly simplifies the design power of the switch mode. Other features include the guarantee ± 4%tolerance conditions of the output voltage within the specified input voltage and output load range, and ± 10%of the oscillator frequency. The outside includes shutdown, with 50 Weire (typical) spare current. The output switch includes weekly current limits and heat shutdown for failure conditions.

Features

3.3V, 5V, 12V, 15V, and adjustable output publish 4%maximum value line and load conditions

Guarantee 1A output current

Wide input voltage range, high voltage type is 40V to 60V

Only 4 external components

52 kHz fixed frequency internal oscillator

TTL closing ability, low power standby mode

High efficiency

Use the ready -made standard electrical sensor

[123 ] Hot Portal and Flow Limitation Protection

P+product enhancement test

Application

Simple and efficient antihypertensive regulator

Effective pre -adjustment of linear regulator Device

The front and reverse converter (Buck Boost) on the card on the card

Typical application (fixed output voltage version)

] Fragics and typical applications

Absolutely maximum rated value (Note 1)

Maximum power supply voltage

LM1575/LM2575 45 伏 [123 [123 ]

LM2575HV 63V

Open/off the input voltage -0.3v ≤V ≤+vin

output voltage to the ground (steady-state) –1v

Gong Internal restrictions

The storage temperature range is -65 ° C ~+150 ° C

The highest knot temperature 150 303C

The minimum ESD rated value (C 100 PF, R 1.5 kΩ) 2 kV

Lead temperature (welding, 10 seconds) 260 degrees Celsius

Rate -fixed value running value

Temperature range

lm1575 55 ° C ≤TJ≤+150 ° C

LM2575/LM2575HV 40 ° C ≤TJ≤+125 ° C

供电电压

LM1575/LM2575 40伏

LM2575HV 60伏

LM1575-3.3、LM2575-3.3、LM2575HV-3.3

[123 ] Electrical characteristics

The specifications of the standard surface are suitable for TJ 25 ° C. The specifications of the black body type are suitable for the entire working temperature range.

All output voltage versions

Electrical characteristics

The specifications of the standard surface surface are suitable for TJ 25 ° C, black body type specifications Suitable for the entire work temperature range. Unless there are other regulations, vehicle recognition numbers of 3.3V, 5V and adjustable versions 12V, 12V version of vehicle identification number 25V, and 15V version of vehicle identification numbers are 30V. Iload 200 mia.

All output voltage versions

Electric characteristics (continued)

The specifications of the standard surface are suitable for TJ 25 ° C, black body, black body, The specifications are suitable for the entire work temperature range. Unless there are other regulations, vehicle recognition numbers of 3.3V, 5V and adjustable versions 12V, 12V version of vehicle identification number 25V, and 15V version of vehicle identification numbers are 30V. Iload 200 mia.

Note 1: Absolute maximum rated value indicates the limit that the device may be damaged. The working rated value represents the state of the device

It is designed to play the function, but does not guarantee specific performance limit. Please refer to the electrical characteristics of the guarantee specifications and test conditions.

Note 2: All limits guaranteed under room temperature (standard surface) and extreme temperature (thick body surface). All limits are used to calculate the average value

The quality level of the factory is 10%production inspection.

Note 3: All limits guaranteed under room temperature (standard surface) and extreme temperature (thick body surface). All room temperature is limited to 100%production test. Use standard statistical quality control (SQC) method to ensure all the limit at extreme temperatures through correlation.

Note 4: External components such as capturing diode, inductance,Input and output capacitors affect the performance of the switching regulator system. When the LM1575/LM2575 uses the test circuit as shown in Figure 2, the system performance will be electrical characteristics as shown in the system parameter part.

Note 5: Output (pin 2) source current. Without a diode, the inductance or capacitor is connected to the output pin.

Note 6: Feedback (pin 4) removed and connected to 0V from the output end.

Note 7: Remove the feedback from the output end (pin 4) and connect to+12V (suitable for adjustable, 3.3V and 5V versions) and+25V Forced output transistors are turned off.

Note 8: VIN 40V (60V for high -voltage versions).

Note 9: The 5th lines of the vertical installation of the 220 packaged environmental thermal resistance (no external radiator), the socket or PC has a board with the smallest copper area of 1/2 inch lead.

Note 10: The ambient thermal resistance (no external radiator) connecting to 220 packaged by the vertical installation, 1/2 -inch lead is welded to about 4 square inch copper areas around the PC board guide line.

Note 11: There are about 1 square inch PC plate copper around the wires, which are connected to the environmental thermal resistance. The additional copper area will reduce further thermal resistance. See the hot model with simple software in the exchange mechanism.

Note 12: If you use To-263 packaging, you can reduce thermal resistance by increasing the PC plate area with the package heat connection: use the copper area of 0.5 square inch inch, θja is 50 ° C/W; 1 The square area of the square is 37 ° C/W; 1.6 or more square -inch copper area, and θJa is 32 ° C/W.

Note 13: When the output is short -circuit or overload causes the adjustment output voltage, the frequency of the oscillator is reduced to about 18 kHz about 40%of the rated output voltage. This self -protection characteristics reduce the average power consumption of integrated circuits from 5%to 2%by reducing the minimum duty cycle.

Note 14: See RETS LM1575J for military RETS/SMD.

Typical performance characteristics (Figure 2 circuit)

Typical performance characteristics (Figure 2 circuit) (continued)

[ 123]

Test circuit and layout guide

In any switch regulator, the layout is very important. RAP inert switch current associated with wiring inductances generates the voltage transient that may cause problems. In order to minimize the inductance and grounding circuit, the wire length should be expressed as short as possible. It is best to use a single point ground (as shown in the figure) or ground plane structure. When the adjustable version is used, the programming resistance near the physical positioning regulator,It is short to maintain a sensitive feedback wiring.

Test circuit and layout guide (continued)

LM2575 series antihypertensive regulator design program

program (fixed output voltage version) Example (fixed output voltage version) Give: VOUT adjustment output voltage (3.3V, 5V, 12V, or 15V) vehicle identification number (maximum value) maximum input voltage ILOAD (maximum value) Maximum load current given: VOUT 5V vehicle identification number (maximum value) 20V ILOAD (maximum value) 0.8a

1. Sensor selection (L1) Select the guide (the output voltage is 3.3V, 5V, 12V, or 15V). For other output voltages, it is available. B. Select the guide according to the inductance value, determine the vIN (MAX) and ILOAD (MAX), and pay attention to the inductors code in the area. C. Recognize the inductor value from the inductors code, and select the appropriate inductor Figure 9 in the table shown in it. List parts of the three sensors. The rated value of the selected electrical sensor must be 1.15 x Iload at the LM2575 switching frequency (52 kHz) and the rated current. For information related information, please refer to the chapters of this data table in the app in the application prompt. 1. Sensor selection (L1) A. The use of the selection guide is shown in Figure 4. B. The inductance area of the 20V line and 0.8A line from the selection guide is L330. C. The required inductance value is 330 μH. It can be seen from the table in Figure 9, select AIE 415-0926, pulse engineering

PE-52627

or RL1952.

2. Output capacitor selection (COUT) A output capacitor and inductance define the extremely pair of control switch regulator circuit. In order to stable work and acceptable output ripple voltage, (about 1%of the output voltage) is recommended to use 100 μF and 470 μF. B. The rated voltage of the capacitor should be at least out of the output voltage. For 5V regulator, the rated value is at least 8V, and the recommended rated voltage is 10V or 15V. High -voltage electrolytic capacitors usually have a lower ESR number, so a rated voltage may need to be selected higher than the usual needs.

2. Output capacitor selection (COUT) A.COUT 100 Micr F reached 470 μF standard aluminum electrolytic. B. The rated voltage of the capacitor 20V.

3. Capture the two -pole tube selection (D1) a. Capture the current fixed value of the diode must be at least 1.2 times the negative current. In addition, if the power supply design must withstand the short circuit of the continuous output, the diode should be equal to LM2575. The maximum pressure of this diode is output overload or short circuit. B. ReverseThe rated value of the voltage diode should be at least maximum input voltage. 3. Capture the diode selection (D1) A. For this example, A 1A rated current is sufficient. B. Use 30V 1N5818 or

SR103

Schottky diode, or the rapid recovery of the diode as shown in Figure 8.

4. Input capacitors (CIN) aluminum or cricket electrolytic bypass electric containers near the regulator need to run stably.

4. Input capacitors (CIN) A 47 μF, 25V aluminum electrolytic is located in the capacitor near the input and ground pins to provide a sufficient bypass

inductive value selection guide (for continuous mode operation) [ 123]

Program prompt

Input capacitors (CIN)

In order to maintain stability, the regulator input pin must be with at least 47 μF electrolytic container together pass. The leader of this capacitor must keep a short distance and is located in the regulator. If the operating temperature range includes the temperature below -25 degrees Celsius, the input capacitor value may require a larger. For most electrolytic containers, with the decrease in temperature and age, blood sinks decreased, and blood sinks rose. Paided ceramics or solid cavities will improve the stability of the regulator at low temperature. For the maximum working -life capacitor of the capacitor, the rated value of the moral root ripples of the capacitor should be greater than

The sensor selection

All the switching regulators have two basic operation modes: continuous and discontinued of. The difference between the two two types are related to the continuity of the inductance current or in the normal switching cycle. Each mode has obvious differences that can affect the performance and requirements of the regulator's performance and requirements. LM2575 (or any simple switch series) can be used for continuous and discontinuous operation mode. The inductance value selection guide in Figure 3 to 3 is a continuous inductor current. When the inductance value shown in the inductive selection guide, the current of peak -to -peak electrical ripples is about the maximum DC current. Under a relatively heavy load current, the circuit working current in continuous mode (electrical sensor) is always flowing), but under light load conditions, the circuit will be forced to the discontinuous mode (the sensor current has fallen to zero within a period of time to zero zero for a period of time To. This discontinuous operation mode is fully acceptable. For light loads (less than about 200 mia), the regulator may need to be operated in the discontinuous mode, mainly because the inductance value required by the Discon continuous mode is low. Select the guideline to select suitable continuous mode operations, but if the inductance value is too high, the designer should investigate the possibility of non -continuous operation. Computer design simple software switches will provide value operations of all component discontinuous (and continuous) modes.

There are different types of inductors, such as pots, compound surfaces, E -shaped frames, line axis cores, etc., as well as different core iron oxygen and iron powder. The minimum expensive wire -shaft core is wrapped in metal silk on the iron oxygen rod core. This structureMakes cheap inductances, but because the magnetic flux is not fully included in the core, it will produce more electromagnetic interference (EMI). This electromagnetic interference can cause problems in sensitive circuits, or may give incorrect scope reading because of the inductive voltage in the oscilloscope probe. The inductors listed in the table include the core structure of the iron oxygen groove AIE, the pulse engine engineering, and the core of the iron oxygen line shaft. The operation of the inductor should not exceed its maximum rated current because it may be saturated. When the sensor begins to be saturated, the inductor quickly reduces the inductors to start to look mainly resistant (DC resistance). This will cause switching current to rise rapidly. Different inductance types have different saturation characteristics, and should be kept in mind when selecting the inductor. The data table of an inductor manufacturer includes the energy restrictions of current and avoiding inductive saturation.

Direct ripple current

When the switch is running in a continuous mode, the inductive current waveform shaped from triangular to sawtooth wave types (depending on the input voltage). For a given input voltage and output voltage, the peak-peak amplitude of the current waveform of the induction is unchanged. When the load current rises or decreases, the entire sawtooth current waveform also rises or decreases. The value of the average DC electricity is equal to DC load current (configuration in the antihypertensive regulator). If the load current drops to a sufficiently low level, the jagged current waveform will reach zero, and the switch switch will be switched to the discontinuous operation mode. This is a fully acceptable operation mode. Any dollar switching regulator (no matter how large the inductor value is, if the load current is light enough.

output capacitor

requires an output capacitor The capacitor should be located near LM2575 using short PC traces. Standard aluminum electrolytic is usually sufficient, but ESR is low for low output ripple voltage and stability. The ESR of the capacitor depends on some factors including: voltage value, rated voltage voltage, voltage voltage , Physical dimensions and structure types. Generally speaking, low -value or low voltage (below 12V) electrolytic capacitors have higher blood sink. The size of the output ripple voltage is mainly ESR (equivalent series resistance) and inductive ripples that output capacitors The amplitude of the current (dIind). See the chapters of the electrical ripple current in the application prompt. The lower capacitance (220 μF – 680 μF) will allow a typical 50 MV to 150 MV output ripple voltage, and the larger ones The capacitance value will reduce the ripple to about 20 MV millivolves to 50 millivolves. Output ripple voltage (∏IIND) (COUT's ESR) In order to further reduce the output ripple voltage, several standard electrolytic capacitors can be connected in parallel, or more High -level capacitors can be used. This kind of capacitor is usually called high -frequency "