Two lithium battery charging management IC detection knowledge:
    1, do not easily determine the damage of integrated circuits
    Do not easily judge that the integrated circuit is damaged. Because the vast majority of integrated circuits are directly coupled, once a circuit is abnormal, it may lead to multiple voltage changes, and these changes are not necessarily caused by integrated circuit damage, in addition, in some cases, when the measured pin voltage is consistent with or close to the normal value, it may not always be able to show that the integrated circuit is good. Because some soft faults do not cause a change in the DC voltage.
    2. Test to avoid short circuit between pins
    When measuring voltage or testing waveform with oscilloscope probe, avoid short circuit between pins, ** measurement is performed on peripheral printed circuit in direct communication with pins. Any instant short circuit can easily damage the integrated circuit, especially when testing CMOS integrated circuits in flat packages.
    3. It is strictly prohibited to use the grounded test equipment to contact the TV, audio, video and other equipment that is live on the bottom plate without the isolation transformer
    It is strictly forbidden to directly test TV, audio, video and other equipment without power isolation transformer with the equipment whose shell has been grounded. Although the general radio recorder has a power transformer, when it comes to the more special TV or audio equipment, especially the output power is larger or the nature of the power supply is not well understood, it is necessary to first find out whether the chassis of the machine is charged, otherwise it is easy to cause short circuit of the power supply with the TV, audio and other equipment that is charged on the bottom plate, affecting the integrated circuit, resulting in further expansion of the fault.
    4, to understand the working principle of integrated circuits and related circuits before detection
    Before checking and repairing integrated circuits, we must first be familiar with the function of the integrated circuit used, the internal circuit, the main electrical parameters, the role of each pin, the normal voltage of the pin, the waveform and the working principle of the circuit composed of peripheral components.
   5, to ensure the quality of welding
    The welding is really solid, and the accumulation of solder and porosity are easy to cause virtual welding. The welding time is generally not more than 3 seconds, and the power of the soldering iron should be about 25W of internal heat. The soldered integrated circuit should be carefully checked, ** Use an ohmmeter to measure whether there is a short circuit between the pins, and confirm that there is no solder adhesion before switching on the power supply.
    6, pay attention to the insulation properties of the soldering iron
    Do not allow the use of electric soldering iron welding, to confirm that the iron is not charged, the shell of the iron is grounded, the MOS circuit should be more careful, can use 6~8V low-voltage soldering iron is safer.