In the DCDC power supply test, the Load Transient Test is a very important part. The load transient test can be used to quickly evaluate the stability and rapidity of the tested power supply. In the selection of the DCDC converter chip When the load transient test performance is also an important reference for evaluating the dynamic performance of the chip. The figure below is a typical waveform of a DCDC converter load transient test, CH3 is the AC component of the output voltage, and CH4 is the load current.Note that the rising slope and falling slope of the load current are not the same, a slower rising slope corresponds to a smaller voltage drop (Undershoot), and a steep falling slope corresponds to a larger . IGBTs
Load transients are usually tested with an Electronic load (E-Load). As mentioned earlier, the slew rate of the load will have a critical impact on the test results. However, due to the internal circuit limitations of the device, conventional electronic loads can achieve The di/dt will not be very high. In addition, due to factors such as the design of different manufacturers, the hopping rate that can be achieved by different types of electronic loads is not the same, as shown in Figure 2(a)(b) below. The two figures are respectively Models A and B compare the actual current rising slope when the same setting is 2.5A/us. It can be seen that the actual current jump slope is much smaller than the set value, and the jump slope of different models is different. This may cause the power transient test results to be more than ideal, or the performance evaluation between different chips is not objective enough. Therefore, it is of great engineering significance to design a simple and practical electronic load with a load jump slope that can meet the experimental requirements.