# Driving the future of technology : Original solution in measurement and control

## Lecture for Measurement

Posted 2020/2/26

### DC-power-supply (AC-DC power supply)

Contents List

#### 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 switching type is small and highly efficient but noisy, while linear regulator type is poor efficient but low noise.

Table 1: Performance differences between 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 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 achieve high efficiency of 80 % or more. And, many of 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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