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 Lecture for Measurement

Posted 26/02/2020

DC Power Supply (AC-DC Power Supply)

Circuit Method and Features of DC Power Supply

Here, the DC power supplies that operates by inputting commercial power supply (AC-DC power supplies) are described. DC power supplies are mainly categorized as two types: switching and linear regulator. It is generally known that the switching type is small and highly efficient but noisy, while the linear regulator type is less efficient but has lower noise.


Table 1: Performance differences between the two systems

  Noise Efficiency Size Weight
Switching type system Large Good Small Light
Linear regulator type system Low noise Poor Large Heavy


Therefore, it is necessary to select the appropriate power supply depending on the application. For example, a linear regulator type power supply (which provides low noise and high stability) is suitable as “a power supply for the amplifiers” or “a bias source for the sensors” used for measurement of small signals. For measuring small signals, we provide the LP-series power supplies that have better characteristics in low noise and high stability among linear regulator types.


1. Switching-type System

The switching type system has power loss due to the on-resistance of the switching device, however it achieves high efficiency of 80 % or more and many of the high-frequency transformers are small because the through frequency* is high.

However, noise due to switching (switching frequency and its harmonic components) appears at the output, and the noise performance is poor compared to that of the linear regulator type system.

*Generally, switching frequency is around 20 kHz to 1 MHz.

Figure 1: Schematic of switching-type DC power supply

Related Product

Low-noise DC Voltage Source LP6016-01/P

Bias-voltage and control-voltage source for sensors and devices.

  •  Low noise: 10 µV/√Hz (Bandwidth: 10 Hz to 20 MHz)
  •  High stability: ±10 ppm/°C
  •  Setting accuracy: ±(0.03%+250µ V)
  •  Output voltage: 0 to +16.1 V (LP6016-01)
         0 to +16.1 V x 2ch (LP6016-01P)
  •  Output current: 100 mA
  •  External control interface: USB, RS-232, LAN



Related keywords :  Low Noise DC Voltage Source

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