Outpvut resistance indicators for use with regulated power supplies
Quality Indicators of Voltage Regulated Power Supplies
The output voltage Uo of the voltage regulator circuit will be affected by three factors, namely, the input voltage UI, the load current Io and the ambient temperature T, i.e.
Uo = f (UI, Io, T)
Therefore, the general expression for the amount of change in the output voltage of the regulated power supply can be written as Uo = f (UI, Io, T)
It can be seen that the four main indicators reflecting the quality of DC regulated power supply are Su, Ro, ST, Ur. The following are described as follows:
(1) Input Adjustment Quotation and Voltage Regulation Factor
We will rectify the filtered input voltage change, and the resulting output voltage change ratio, called the input voltage regulation factor. In fact, the ratio of the relative changes in output voltage and input voltage is often used to characterise the voltage regulation performance of the power supply, which is called the voltage regulation factor.
(2)Output resistance
Under the condition of constant input voltage and temperature, the ratio of output voltage change and load current change is defined as output resistance, which is recorded as
The negative sign in the formula indicates that ΔUo changes in the opposite direction to ΔIo.
(3) Temperature coefficient
In the case of input voltage and load circuit are unchanged, the unit temperature change caused by the output voltage change is the temperature coefficient of the regulated power supply or temperature drift, recorded as
(4)Ripple voltage
In the case of the rated operating current, the value of the AC component of the output voltage becomes the ripple voltage. The symbol for the rms value of the ripple voltage is Ur, and UIr can be regarded as the amount of change in the input voltage. Obviously, the voltage regulator circuit itself suppresses this amount of variation. So Ur≈SuUIr
Sometimes also commonly used ripple suppression ratio to illustrate the size of the ripple voltage, writing 20lg (UIr/Ur) (dB), it is clear that the larger the ripple suppression ratio the better.
For a high-performance voltage regulator circuit, the four indicators described above, the smaller the better.
