Transient response

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Transient response is when the load absorption current jumps, which causes the voltage at the power supply output to deviate from the set value instantly.

First, let's look at this waveform (Figure 1). The voltage drops by about 120 mV and lasts for about 30 uS. This is the output of a high-performance programmable power supply. When the load current increases suddenly, the output voltage changes instantly.

Figure 1: Output voltage changes when the load current jumps from 1 mA to 500 mA

This is a problem that exists in any power supply. When the load absorption current jumps, the voltage at the power supply output terminal will instantly deviate from the set value. This screenshot of the oscilloscope screen (Figure 1) shows that when the load current of a power supply changes from 1mA to 500mA, the output voltage undergoes a 30uS instantaneous change.

This characteristic of the power supply is what we usually call the load transient recovery time, or transient response time. It represents the time required for the power supply voltage to recover to the set range when the load current changes suddenly. As shown in Figure 2:

Figure 2: A sudden change in load current causes a transient response in the power supply voltage

When characterizing the transient response of a power supply, we consider three points:

The magnitude of the load changes, for example, the load jumps from 50% of the full load to 100% load. For a power supply with a maximum output current of 10 A, the load current jumps from 5 A to 10 A.
The power supply starts to change and recovers to a certain range of the set voltage before the load change. It should be noted that due to the dual influence of the load change and the load effect of the power supply, the power supply voltage cannot return to the value before the load change. In this way, we will standardize a range, such as recovering to within ±20 mV of the voltage before the load change, or within ±0.1%.
The transient response time is the time value required for the voltage to recover to the specified power supply range.

se7ens

Is this what is circulating on the Internet:

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se7ens posted on 2021-5-26 14:03 Is this what is circulating on the Internet: Everything was fine when I came here, but I can't go back...

Mainly the change of load and the load effect of power supply