The following circuit schematic designed according to the device manual works abnormally. The design is as follows: 12V input, connected with five filter capacitors to the ground; Four circuits of 3.3V, 2.5V, 1.5V and 0.9V are output respectively. The output is first disconnected from the load through magnetic beads, and then connected to 47uF capacitor to the ground; RUN is connected to the input 12V, TRACK/SS is connected to 0.1uF to the ground, FB is connected to the resistance to the ground, and the resistance value corresponds to the voltage value, which is determined to be consistent with the manual; 4-way INTVCC is connected with 4-way MODE respectively. Each PGOOD pulls up 10K to the corresponding INTVCC. Test condition: When the input is 12V, the output is 5.5V, 5.5V, 3.9V and 1.3V respectively, which is higher than the design output value. (At this time, the load is disconnected and the magnetic bead is not welded) INTVCC is 3.3V, the voltage of the first FB circuit is between 1.1~1.2V, and the latter circuits are reduced in turn. After the first circuit is connected with the magnetic bead and the load, the output is 3.9V, and the VFB becomes 0.6V (without connecting the load of other circuits to avoid burning things). Each circuit is about 0.4V higher than the design value; Then reduce the input voltage. When it is reduced to 5V, the output is about 3.4V At 4V input, the output is about 3.2V At present, the main test situation is this. The welding problem is under investigation, and it can't be determined whether there is a problem. How can I determine whether it is the circuit design problem or the chip itself Two chips on the same board have the same problem, so they dare not change chips at will (the probability of two chips having problems at the same time is relatively small The following circuit schematic designed according to the device manual works abnormally. The design is as follows: 12V input, connected with five filter capacitors to the ground; Four circuits of 3.3V, 2.5V, 1.5V and 0.9V are output respectively. The output is first disconnected from the load through magnetic beads, and then connected to 47uF capacitor to the ground; RUN is connected to the input 12V, TRACK/SS is connected to 0.1uF to the ground, FB is connected to the resistance to the ground, and the resistance value corresponds to the voltage value, which is determined to be consistent with the manual; 4-way INTVCC is connected with 4-way MODE respectively. Each PGOOD pulls up 10K to the corresponding INTVCC. Test condition: When the input is 12V, the output is 5.5V, 5.5V, 3.9V and 1.3V respectively, which is higher than the design output value. (At this time, the load is disconnected and the magnetic bead is not welded) INTVCC is 3.3V, the voltage of the first FB circuit is between 1.1~1.2V, and the latter circuits are reduced in turn. After the first circuit is connected with the magnetic bead and the load, the output is 3.9V, and the VFB becomes 0.6V (without connecting the load of other circuits to avoid burning things). Each circuit is about 0.4V higher than the design value; Then reduce the input voltage. When it is reduced to 5V, the output is about 3.4V At 4V input, the output is about 3.2V At present, the main test situation is this. The welding problem is under investigation, and it can't be determined whether there is a problem. How can I determine whether it is the circuit design problem or the chip itself Two chips on the same board have the same problem, so they dare not change chips at will (the probability of two chips having problems at the same time is relatively small
