DCDC power supply burns out at the moment of power-on

z45217

DCDC power supply burns out at the moment of power-on [Copy link]

 

As the title says, what is the common reason and how to avoid it? I use a 12V to 5V DCDC chip, and sometimes it burns out when powered on.

I bought a SIM module yesterday, which also has a DCDC chip. I used it a few times, and it caught fire instantly when I connected the 12V to the module in the afternoon. I don't know why.

Please advise how to avoid this situation.

There are several AC to DC12V power supplies. The one below burned out the SIM module yesterday.

I don't know what the DCDC chip on the SIM module is.

My own board is SY8201ABC

wangerxian

What is the power supply? What is the model of the 12V to 5V DCDC chip? If you drew the circuit yourself, could you please send me the circuit diagram?

z45217

wangerxian posted on 2023-3-3 16:03 What is the power supply? What is the model of the 12V to 5VDCDC chip? If you drew the circuit yourself, can you please send the circuit diagram?

I have uploaded and re-edited the post, thank you.

呜呼哀哉

z45217 posted on 2023-3-3 17:08 I have uploaded and re-edited the post, thank you

Why do you need to add C2 for compensation? I checked the datasheet for this model and found that it only has 3 pages. There is no description of the error amplifier and no description of compensation. When you tested it, was the output stable?

吾妻思萌

Is it recommended to gradually check the board to find out the many test pads?

led2015

The DCDC power supply may burn out at the moment of power-on for the following reasons:

1. Instantaneous overcurrent: At the moment of power-on, a large instantaneous current will appear in the circuit because the load capacitor circuit needs to be charged. If the DCDC power supply is not designed properly, the output voltage will deviate greatly from the set value instantly, which will cause the DCDC power supply to burn out.
2. Insufficient overvoltage/overcurrent protection: The DCDC power supply needs to have overvoltage/overcurrent protection function during normal operation to protect the load and the DCDC power supply itself. If the protection function is insufficiently designed or fails, the DCDC power supply will burn out at the moment of power-on.
3. Design defects: Defects in the DCDC power supply design, such as unreasonable selection of components and unreasonable circuit layout, may cause the DCDC power supply to burn out at the moment of power-on. In order to solve this problem, you can consider adopting a more reasonable DCDC power supply design, adding overvoltage/overcurrent protection circuits, optimizing circuit layout and component selection, so as to improve the stability and reliability of the DCDC power supply. At the same time, it is also necessary to check whether there are problems with the load circuit, such as whether there is a large capacitance load circuit, etc. These factors need to be taken into consideration during the design.

hahajing

First: The ac/dc and dc/dc you chose are both small brands, the parameters may not be guaranteed, some indicators may not meet the requirements, and a group pulse stage is broken. Second: The input and output capacitance is too small, at least at the level of hundreds of microfarads, and basic operations may cause overload. The chip is not very good, so it is directly messed up.

z45217

Alas, posted on 2023-3-3 17:17 Why do we need to add C2 for compensation? I checked the information of this model, and the datasheet is only 3 pages, without any description of the error amplifier, nor about compensation, ...

I directly follow the typical application picture on the first page

聋门叨客

The description is not very clear. Which part is burned? Is it the power chip that is burned? Generally speaking, this type of chip has a soft start and the current limiting is relatively fast, so overcurrent is ruled out. You have to use an oscilloscope to see specifically how much the instantaneous voltage is when powered on. It is most likely overvoltage breakdown. I personally recommend configuring appropriate electrolytic capacitors for input and output. Due to the parasitic inductance on the power adapter cable and PCB traces, appropriately increasing the ESR of the input capacitor can reduce the overshoot of the instantaneous voltage when powered on. If space is limited and electrolytics cannot be used, it is recommended that the fuse be replaced with a 0.5 or 1 ohm resistor to solve the problem, but this will increase power consumption. If your resettable fuse is used to prevent reverse connection, it is recommended to place it in front of the diode so that it can provide reverse connection protection.

z45217

Longmendaoke published on 2023-3-4 16:31 The description is not very clear. Which part is burned? Is it the power chip? Generally speaking, this kind of chip has soft start and current limiting is also relatively fast, so...

Thanks

秦天qintian0303

The possibility of overcurrent is not high, and there is no load. I also encountered an abnormality when using TPS5450 before. At that time, a tantalum capacitor was soldered upside down.

z45217

Longmendaoke published on 2023-3-4 16:31 The description is not very clear. Which part is burned? Is it the power chip? Generally speaking, this kind of chip has soft start and current limiting is also relatively fast, so...

The DcDc chip caught fire the moment it was plugged in, but other circuits were fine. The sim module requires 10w of power. The series resistor method is not suitable for large currents. Can an inductor be used instead?

z45217

hahajing posted on 2023-3-3 22:48 First: The ac/dc and dc/dc you chose are small brands, the parameters may not be guaranteed, some indicators may not meet the requirements, and a group pulse post-stage is broken. ...

Thank you for your answer. Due to space issues, I cannot use large capacitors. Can I replace the self-recovery fuse with an inductor or resistor to reduce the damage rate?

zhangdaoyu

You can do an experiment to see if the output current can reach 1A. I always choose 2A 3A DC chips.

chunyang

A momentary fire indicates a short circuit or reverse polarity of the input power.

zgc135

You can try to add a protection circuit to increase the suppression of the tip pulse, or try other chips.