LM2575 Adjustable Voltage Regulator Manufacturer, Layout Guidelines, Applications and Other Details
01 December 2023
Ⅱ. Manufacturer of LM2575 voltage regulator
Ⅲ. What are the features of LM2575 voltage regulator?
Ⅳ. The pin configuration of LM2575 voltage regulator
Ⅴ. How does the LM2575 voltage regulator work?
Ⅵ. LM2575 test circuit and layout guidelines
Ⅶ. What are the applications of LM2575 voltage regulator?
Ⅷ. LM2575 voltage regulator dimension and package
Ⅸ. LM2575 voltage regulator design considerations
The LM2575 series voltage regulator is a monolithic integrated circuit. It provides all the active functions of a buck (or boost) switching regulator, is capable of driving 1A loads, and has excellent line and load regulation. It incorporates an internal fixed oscillator, which allows it to form a highly efficient voltage regulator circuit with very few peripheral components. In addition, it has a switching operating frequency of 52KHz.
The LM2576 series consists of the LM1575, LM2575, and LM2575HV, of which the LM1575 is a military-grade product, the LM2575 is a standard voltage product, and the LM2575HV is a high-voltage input product. Each product family offers different voltage grades, such as 3.3V, 5V, 12V, 15V and adjustable (ADJ). Except for military grade products, the two series are offered in a variety of packages such as molded DIP-16 pin, TO-200 straight pin, TO-220 curved pin and surface mount DIP-24 pin.
Replacements and equivalents:
• LM2675
• LM2677
• LM7912
• LM2596
• MP2307
LM2575 is manufactured by National Semiconductor. The company is headquartered in Santa Clara, is a leading developer of analog power management technology, the production of a wide range of power management products. These include easy-to-use integrated circuits, PowerWise products that improve system energy efficiency, and SolarMagic products that increase the amount of power generated by solar energy systems. National Semiconductor's key markets include wireless headsets, displays and a number of broad electronics markets including automotive, medical, industrial and test and measurement applications.
In 2011, TI acquired National Semiconductor for $6.5 billion. The acquisition significantly enriches TI's product portfolio with power management ICs, graphics card drivers, audio amplifiers, communications interface products and data conversion solutions, while laying the foundation for next-generation signal processing.
• Low power consumption: When working with a wide range of input voltages, it only needs to add appropriate heat sinks to work normally.
• Good stability: It has good stability, and the output voltage stability can reach 5‰.
• Built-in filter to suppress power supply jitter: LM2575 contains some filter capacitors internally to help reduce ripple and noise in the output voltage.
• High efficiency: LM2575 adopts fixed frequency PWM control technology, allowing it to work under high efficiency. In typical applications, its efficiency can reach over 90%.
• Adjustable output voltage: Its output voltage can be adjusted through external resistors to adapt to different application scenarios.
• Wide input voltage range: Its input voltage range is 4V to 40V, which is suitable for a variety of power input conditions.
• Internal overheating and short circuit protection: LM2575 has overheating and short circuit protection mechanisms to ensure safe operation of the chip under extreme conditions.
• Low dropout design: LM2575 is a low dropout linear regulator. It achieves a stable output voltage by effectively adjusting the voltage difference between input and output while avoiding wasting excessive power.
As shown in the picture, LM2575 has a total of 5 pins, whose names and descriptions are as follows.
Pin 1 (Vin): Input voltage pin
Pin 2 (OUT): Output pin
Pin 3 (GND): Ground pin
Pin 4 (FB): Feedback pin
Pin 5 (ON’/OFF): Complement on/Off pin
LM2575 adopts the working principle of a step-down switching regulator, which periodically connects the input voltage to the output voltage through the switching of the switching tube, thereby achieving a stable output voltage. Its core components include capacitors, inductors, switching tubes and feedback control circuits.
During operation, when the input voltage passes through the switching tube and is connected to the inductor, the inductor stores electrical energy. When the switch is turned off, the inductor releases the stored electrical energy and continues to deliver current to the output capacitor to meet the load. By controlling the switching period and duty cycle of the switching tube, it can achieve a stable output voltage.
The LM2575 also has a feedback control circuit for regulating the output voltage. When the output voltage is lower than the set value, the feedback control circuit increases the duty cycle of the switching tubes, thereby increasing the output voltage; when the output voltage is higher than the set value, the feedback control circuit decreases the duty cycle of the switching tubes, thereby decreasing the output voltage to achieve a stable output voltage.
As in any switching regulator, layout is very important. The fast switching currents associated with the wiring inductance generate transient switching voltages that can cause problems. To minimize stray inductance and ground loops, the lead lengths shown in bold should be as short as possible. For best results, a single point ground (as shown) or a ground plane structure should be used.
• Power adapter
• Communication device
• Medical equipment
• LED lighting
• Automated industry
• Automotive electronic systems
• Power supplies for electronic equipment
Taking the LM2575T-5.0 as an example, it uses a TO-220 package with a length of 10.54mm, a width of 4.57mm, and a height of 9.40mm.
When designing a circuit using LM2575, we should pay attention to the following points (taking LM2575T-5.0 as an example).
1. Diode selection
The rated current value of the diode should be greater than 1.2 times the maximum load current. At the same time, we should also consider the risk of load short circuit, so the rated current value of the diode should be at least greater than the maximum current limit of the LM2575. In addition, in order to ensure that the diode can work properly, its reverse voltage should be greater than 1.25 times the maximum input voltage.
2. Selection of inductor
We can find the required inductance value based on the output voltage level, maximum input voltage, maximum load current and other parameters and refer to the corresponding inductance curve.
3. Selection of input and output capacitors
The input capacitor should be greater than 47uF and as close to the circuit as possible. The recommended capacitance of the output capacitor is 100 uF to 470 uF, and its withstand voltage value should be greater than 1.5 to 2 times the rated output. For 5V voltage output, it is recommended to use a capacitor with a withstand voltage of 16V.
Frequently Asked Questions
1. What is the use of LM2575T?
The LM2575T-5G is a step-down Switching Regulator ideally suited for easy and convenient design of a step-down switching regulator (buck converter). It is designed to minimize the number of external components to simplify the power supply design.
2. What are the three 3 basic types of voltage regulators?
There are three types of Switching voltage regulators: Step up, Step down, and Inverter voltage regulators.
3. Can the LM2575 be used for adjustable voltage output?
The LM2575 is available in fixed voltage versions. If adjustable voltage is needed, one may consider using a different IC, such as the LM2576, which is an adjustable version of the LM2575.
4. What are some common applications of the LM2575?
The LM2575 is often used in various electronic devices and circuits, such as power supplies, battery chargers, and other applications where a stable and regulated voltage is required.
5. What is the adjustable voltage regulator?
An adjustable voltage regulator produces a DC output voltage, which can be adjusted to any other value of certain voltage range. Hence, adjustable voltage regulator is also called as a variable voltage regulator. The DC output voltage value of an adjustable voltage regulator can be either positive or negative.
