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Technical Terms

Line regulation is a specification that quantifies how much the output voltage (Vout) of a power supply changes in response to fluctuations in its input voltage (Vin). Ideally, the output voltage should remain constant regardless of input voltage changes, resulting in a line regulation of 0%. It is often expressed in percent per volt (%/V) and calculated as follows:

Line Regulation (%/V) = ((ΔVout / Vout>) / ΔVin) x 100

where ΔVout is the change in output voltage, Vout is the nominal output voltage, and ΔVin is the change in input voltage. For example, if the input voltage changes from 100 V to 110 V (a ΔVin of 10 V) and the 5.00 V nominal output voltage shifts to 5.05 V (a ΔVout of 0.05 V), the line regulation is calculated as: ((0.05 V / 5.00 V) / 10 V) × 100 = 0.1 %/V

Line regulation is typically measured by varying the input voltage across its specified range (e.g., ±10% of the nominal value) while maintaining a constant, full-rated load. The test is usually performed at a standard ambient temperature of 25℃. A lower line regulation value indicates better output stability against input voltage changes.

Good line regulation is particularly critical in applications with unstable input power sources or high levels of electrical noise, such as in industrial and automotive environments. In high-precision electronic devices, poor line regulation can compromise performance and accuracy, requiring careful design and component selection.

To improve line regulation, engineers utilize feedback control loops, high-gain error amplifiers, and stable voltage references. These techniques work together to ensure a stable output voltage even when the input voltage varies.