DC charging efficiency issues

zhangdaoyu

DC charging efficiency issues [Copy link]

 

As shown in the figure, two lithium batteries are charged, and the designed charging current is 1A. After testing: input 11.1V current 0.71A charging output: 7.8V/0.82A charging efficiency is about 81%

Charging for half an hour, the inductor and chip were tested with a temperature measuring device at about 72 degrees, and the board temperature was 30 degrees

Question: How can we improve the efficiency of DC charging? What factors affect the efficiency of DC? Can anyone tell me? Is the layout unreasonable? Are there any other convenient methods?

Fred_1977

1. Increase the heat dissipation area. 2. The inductance can be appropriately reduced. 3. The VIN/VOUT traces should be as thick as possible. 4. What is the efficiency of the chip as specified in the chip specification?

zhangdaoyu

Fred_1977 posted on 2022-4-15 14:23 1. Increase the heat dissipation area. 2. The inductor can be appropriately reduced. 3. The VIN/VOUT traces should be as thick as possible. 4. How efficient can the chip be in the specification sheet...

No, one of the parameters is 83%.

zhangdaoyu

This is his manual. The temperature I tested may not be very accurate, but the data is reliable.

Fred_1977

The data sheet says 83, which is about right. If you use an inductor with a smaller DCR, the improvement won't be much. Using MPS will be more efficient.

PowerAnts

Do you have any idea of efficiency? Efficiency is required. Let alone asynchronous operation, how dare you choose such a large sampling voltage drop and BJT process device?

PowerAnts

I don't save specs for this kind of film, I just delete it after watching it.

Gen_X

Your parameters are already good!

In addition to the inductor, you can also consider replacing the 5821 with a better one, because the voltage drop of 5821 is not small enough.

zhangdaoyu

PowerAnts posted on 2022-4-16 09:04 Do you have any idea of efficiency? Efficiency is required. Let’s not talk about asynchronous. How dare you choose such a large sampling voltage drop and BJT process devices?

It seems that I have met someone who knows the business. I don’t do much charging products, so I didn’t pay much attention to this.

zhangdaoyu

Gen_X posted on 2022-4-16 11:56 Your parameters are already pretty good! In addition to the inductor, you can also consider replacing it with a better 5821, because the voltage drop of 5821 is not small enough.

Thank you. Is it true that the voltage drop of the diode selected here should be as small as possible?

zhangdaoyu

Fred_1977 posted on 2022-4-15 19:02 The data sheet says 83, which is about right. Use an inductor with a smaller DCR. If you improve it further, it won't be much. Using MPS is more efficient.

I think MPS is an imported chip. I would rather lose some efficiency than choose domestic chips. This is controllable.