【USB charger DIY】Connect current sensor

dcexpert

【USB charger DIY】Connect current sensor [Copy link]

I have been busy lately and the progress is slow. Today I took some time to weld the current detection part. There is no current detection signal on the fast charging module. In order to measure the current, it is necessary to use the detection circuit of the application. Hall sensors or current amplifiers are generally used to measure current. The ACS712ELCTR Hall sensor is used here. It is a bidirectional current detection chip that can measure ±5A/±20A/±30A current. The power here is not large, so the ±5A model is just right.

In order to detect the current, it is necessary to find the appropriate signal connection point on the fast charging module. If each USB is detected separately, the most detailed detection can be achieved, but it will increase the complexity and require more flying wires. In the end, it was decided to only collect the total current of each module this time. The front and back of the fast charging module are shown in the figure:

The total current can be obtained from the inductor, so the Hall sensor needs to be connected in series with the inductor. In order to minimize damage to the PCB, one pin of the inductor can be soldered off and then connected with a flying wire. The pins of the inductor are usually glued and need to be scraped off before soldering.

Then connect the flying wires.

hjl2832

The Hall sensor will be disturbed by the magnetic field of the switching transformer, resulting in measurement errors. Be careful to keep it away from transformers and inductors.

dcexpert

hjl2832 posted on 2024-4-9 07:56 The Hall sensor will be disturbed by the magnetic field of the switching transformer, resulting in measurement errors. Be careful to stay away from transformers and inductors.

There is indeed this problem, I will pay attention to it

wangerxian

You made three?

dcexpert

wangerxian posted on 2024-4-9 15:08 The boss has made three?

3 in a box

秦天qintian0303

What is the current sensing accuracy?

dcexpert

Qintianqintian0303 posted on 2024-4-10 08:47 What is the current detection accuracy?

The test has not started yet (under assembly). Theoretically, the sensitivity of the Hall effect chip is relatively high and the response speed is also relatively fast. For chip information, please refer to LiChuang:

https://item.szlcsc.com/45473.html

dcexpert

Qintianqintian0303 posted on 2024-4-10 08:47 What is the current detection accuracy?

According to the current test data, it is basically the same as the USB tester, and the sensitivity is also very high. However, without a very professional instrument, it is hard to say how high the real accuracy is, but it is definitely no problem for general use.