LM2596 usage experience

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LM2596 usage experience [Copy link]

The LM2596 series is a 3A current output step-down switch integrated voltage regulator chip produced by TI. It contains a fixed frequency oscillator (150KHZ) and a reference regulator (1.23v), and has a complete protection circuit,

Current limiting, thermal shutdown circuit, etc. This device only needs a few peripheral devices to form a high-efficiency voltage stabilization circuit. It provides multiple voltage grades such as 3.3V, 5V, 12V and adjustable (ADJ).

A brief introduction to the content:

◆ LM2596 technical features ◆ LM2596 similar devices ◆ LM2596 typical circuit ◆ LM2596 Schottky diode and inductor selection

◆ PCB layout of LM2596 ◆ Heat dissipation of LM2596

1. LM2596 Technical Features
3.3V, 5V, 12V fixed voltage output and adjustable voltage output

●Adjustable output voltage range 1.2V～37V±4%

●Good output linearity and load adjustable

●Output current can be up to 3A

●Input voltage can be up to 40V

●Using 150KHz internal oscillation frequency, it belongs to the second generation switching voltage regulator, with low power consumption and high efficiency

● Low power standby mode, typical IQ is 80μA

●TTL power-off capability

●With overheat protection and current limiting protection function

●Package: TO-220 (T) and TO-263 (S)

●The peripheral circuit is simple, only 4 external components are needed, and standard inductors that are easy to buy are used
2. LM2596 and similar devices

Similar devices to LM2596 include: LM1575, LM2575, LM2576, etc.

For high voltage input: HV version is available, such as LM2576HVT, LM2576HVS, the maximum input voltage can reach 60V;

3. Typical circuit of LM2596

The typical circuit of LM2596 is shown below:

The specific parameters of the circuit can be obtained by going to TI's website and using TI's tools to generate a schematic diagram based on your needs. The parameters are as follows:

If the output ripple requirement is high, LC filtering can be added to the output, as shown in the following figure:

The frequency of the LC filter can be selected, 10~1/20 of the DCDC frequency

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4. Selection of Schottky diode and inductor for LM2596

Schottky diode: commonly used SMD, generally use SS34, if the load current is not very large, you can use SS14, SS24, etc., for larger current, you can consider using SS56; Inductor: choose 33uH/3A, preferably a shielded inductor, if there is no requirement for EMC, you can also choose a plug-in power inductor. The rated current of the inductor is generally 1 times the actual load current.

Because the rated current of the inductor will change due to the influence of temperature, and the quality of domestic products is not necessarily reliable, derating is an important guarantee to improve product reliability, so I usually leave at least 1 times the margin.

quantity;

5. PCB layout of LM2596

It is best to refer to the PDF material for PCB wiring, as shown below:

The following figure is a PCB diagram for reference only:

6. Heat dissipation of LM2596

The following figure is for reference only (lay 1 layer on TopLayer, TopSolder, BottomLayer, BottomSolder, and then place more vias. The vias are generally 35mil in outer diameter and 20mil in inner diameter):

The actual board is paved with ground, and the inductor used is 100uH, for reference only;

dcexpert

The LM25 series has low frequency, large inductance and capacitance, high ripple, and many parallel imports. It has no advantages except being cheap.

okhxyyo

Thanks for sharing

btty038

Use a 12V