LTC4040备用电池方案充电故障及出现负载加载后输入电源停用转由电池升压输出的问题

Hello,

It sounds like you may just have some power limiting issues. For problem 1, does all work well with no load attached? At what load do you start seeing issues? Does charging work normally?

For problem 2, it sounds like one of your adapters may be either hitting its power limit or may have a high series resistance contributing to a voltage drop. Adjusting the PFI threshold may help.

It is a little difficult for me to pick out all of the information from your problem descriptions as I need to translate them to English. Going forward, can you please use shorter sentences and smaller paragraphs to convey the information more efficiently and concisely? Sorry to ask, but it will help both of us solve this faster.

Your schematic looks good, but it may be worth going through the equations in the datasheet to size the external components to your use case. The values shown seem to be those used for the demo board. This is usually ok, but may not be as optimized as possible.

Regards,

Zack

Thank you very much for your reply. I'm very sorry. I thought that the Chinese forum could describe the problem in Chinese. The pictures in the previous description may not be displayed properly due to problems with the website upload. I now need to upload it again. During my debugging process In, it was found that when the finger accidentally touches the grounding resistance of the inverting resistance voltage divider of the PFI comparator, the LTC4040 controller resets, the indicator light that resets flashes, and the charging indicator light also flashes. In the test using an adjustable power supply as the input power, the battery can be charged normally without a load. After the load is increased, the frequency of the SW pin of the controller is still about 2.2Mhz, which is in accordance with the normal switch of BUCK mode. The frequency is only when the current sampling resistance of the fuel gauge of the battery is measured and the charging current of the battery is reduced. I think this is a normal working situation, but when the power adapter of the above picture is used, after the load of the rear stage increases The switching frequency of the SW pin of the LTC4040 will be switched from 2.2Mhz to 1.15Mhz, and the voltage of the input power adapter will increase a little. The voltage drop across the R43 and the input sampling resistor is very small, and there is no manual. The 25mV mentioned in the above, but after adjusting the resistance of the voltage divider resistor of the PFI pin, the first two adapters can be loaded normally, and when the power consumption of the load increases, the charging indicator will go out, but the third adapter is still unable to Under no-load condition, the battery is not charged and the charging indicator and reset indicator will flash.

Figure 1: The first power adapter 5V 4A

Figure 2: The second power adapter with a single-port output capability of 5V 2.4A

Figure 3: The third power adapter is a universal mobile phone adapter

The following figure is the PCB drawing and the schematic diagram of the later adjustment and modification. The parameters after adjusting the device

PCB

Schematic 

Thank you very much for your reply. I'm very sorry. I thought that the Chinese forum could describe the problem in Chinese. The pictures in the previous description may not be displayed properly due to problems with the website upload. I now need to upload it again. During my debugging process In, it was found that when the finger accidentally touches the grounding resistance of the inverting resistance voltage divider of the PFI comparator, the LTC4040 controller resets, the indicator light that resets flashes, and the charging indicator light also flashes. In the test using an adjustable power supply as the input power, the battery can be charged normally without a load. After the load is increased, the frequency of the SW pin of the controller is still about 2.2Mhz, which is in accordance with the normal switch of BUCK mode. The frequency is only when the current sampling resistance of the fuel gauge of the battery is measured and the charging current of the battery is reduced. I think this is a normal working situation, but when the power adapter of the above picture is used, after the load of the rear stage increases The switching frequency of the SW pin of the LTC4040 will be switched from 2.2Mhz to 1.15Mhz, and the voltage of the input power adapter will increase a little. The voltage drop across the R43 and the input sampling resistor is very small, and there is no manual. The 25mV mentioned in the above, but after adjusting the resistance of the voltage divider resistor of the PFI pin, the first two adapters can be loaded normally, and when the power consumption of the load increases, the charging indicator will go out, but the third adapter is still unable to Under no-load condition, the battery is not charged and the charging indicator and reset indicator will flash.

Figure 1: The first power adapter 5V 4A

Figure 2: The second power adapter with a single-port output capability of 5V 2.4A

Figure 3: The third power adapter is a universal mobile phone adapter

The following figure is the PCB drawing and the schematic diagram of the later adjustment and modification. The parameters after adjusting the device

PCB

Schematic 

Hello,

Does your LTC4040's GND paddle have vias through the board connecting to a GND plane?

Is PFO toggling during the problematic operation? I wonder if there is a problem with the adapter. Do you have multiple of that model?

Regards,

Zack