Why is the power supply voltage pulled down from 12V to more than 3V when using lm2596 to stabilize 5V?

峰江大闪电

Why is the power supply voltage pulled down from 12V to more than 3V when using lm2596 to stabilize 5V? [Copy link]

 

Using lm2596 to stabilize 5V, why is the power supply voltage pulled down from 12V to more than 3V? The small light bulb cannot light up and cannot output 5V

bqgup

There may be something wrong with your schematic design. I have a circuit diagram that I have tried myself. The chip is the same as yours, both use LM2596.

topwon

The power supply voltage can be pulled down. Maybe I bought a fake product?

qwqwqw2088

The output of this chip is often pulled down, but there are many reasons for the pull-down. LM2596 is an old DCDC chip, and the circuit is mature after all. Take a good look at the manual and check the parameters of your own components.

maychang

What device is used to power the 12V DC? Is it an adjustable voltage stabilizer used in the laboratory? What is the output current limit?

qwqwqw2088

This forum also often discusses 2596 LM2596 module input voltage is pulled down to 3V https://en.eeworld.com/bbs/forum ... 07&highlight=lm2596 LM2596-5.0 Help as shown in the circuit, the input voltage is pulled down, how to find the reason https://en.eeworld.com/bbs/forum ... 23&highlight=lm2596 Strange problems encountered when using LM2596 https://en.eeworld.com/bbs/forum ... 77&highlight=lm2596 To reduce the voltage of about 25V to about 3.3V, with low power consumption requirements, can't we use LM2596 or something like that? https://en.eeworld.com/bbs/forum ... 12&highlight=lm2596

qq849682862

First test the impedance of Pin1 & Pin4 to ground. If there is no abnormality, it is probably that the front-end power supply (12V) is insufficient. It is recommended to explain the test situation clearly, whether the input and output are loaded, etc.

PowerAnts

Have you bought the Wuxi product?

峰江大闪电

bqgup posted on 2018-9-5 16:06 There may be something wrong with your schematic design. I have a circuit diagram that I have tried myself. The chip is the same as yours, both using LM2596

What is your circuit like?

峰江大闪电

maychang posted on 2018-9-5 16:37 What device is used to power the 12V DC power supply of the original poster? Is it an adjustable voltage stabilizer used in the laboratory? What is the output current limit?

This feeling should be enough

maychang

Fengjiang Lightning published on 2018-9-6 13:40 This feeling should be enough

This should be enough. The output voltage of this adapter is pulled down, which must be a problem with your LM2596.

maychang

Fengjiang Lightning published on 2018-9-6 13:40 This feeling should be enough

The output voltage of this adapter is pulled down. Use a multimeter to measure how much current is when connected to LM2596.

Arvinˇ

What is your maximum output current? It seems that the inductance value is too small.

qwqwqw2088

The inductor in the picture posted on the first floor is 4.7uH, which is much smaller. You can refer to the selection diagram in the manual

lehuijie

The inductor used by the OP is not the kind of carbon film package. In addition, the inductance value is a bit small. For details, please refer to the reference circuit in the manual.