New concept in DC power supply: Low ripple and easy-to-use digital

New concept in DC power supply: Low ripple and easy-to-operate digital DC power supply

DC power supplies are generally divided into linear power supplies and switching power supplies. Linear power supplies are limited by the size and weight of the transformer, so they are generally low in power and heavy in weight. Switching power supplies use a switch switching method, so they have higher power but also higher ripple.
Traditional power supplies generally use pointer or digital display to display the current voltage or current, and use a potentiometer to adjust the desired voltage and current output values. If you want to adjust the precise voltage output, you must use an accurate display instrument for monitoring. Because the resistance characteristics of the potentiometer are nonlinear, it takes a certain amount of time to adjust, and you must be careful about drift, so you have to make do with what you have! !
In order to solve the problems of users, MOTECH Co., Ltd. has developed a fully digital power supply. Its architecture and features are introduced as follows:
1. Basic architecture

The 12-bit D/A converter is used to determine the resolution of voltage and current (which increases or decreases with the size of voltage, current and capacity). The voltage and current sensing (+S) at the output end enables the CPU to automatically help you detect the current output status without worrying about whether the output drift occurs, solving the problem of power supply effect and load effect caused by fluctuations in the mains. Users can clearly see the current output voltage and current status on the LCD display. Because it is controlled by a single-chip microcomputer, you only need to directly enter the required value on the button to get an accurate output. A digital DC power supply with simple operation and great value for money is born.
2. Functional characteristics:
1. Direct calibration of the panel: The most troublesome thing about the whole instrument is the accuracy drift caused by the aging of parts. Therefore, regular calibration is required, which is also clearly specified in the ISO-9000 system. However, in general calibration, it is time-consuming, labor-intensive and expensive, and the calibration workers also have production bottlenecks due to insufficient equipment. Self-calibration, open the case, and don't know where to start with densely packed parts. Let Motech intelligent power supply handle these. You can complete the calibration process by simply pressing a few buttons on the panel, saving time and effort, and you don't need to do regular ISO-9000 calibration.
2. Intelligent expansion: Traditionally, if you buy a power supply, such as 30V/2A, this specification only limits the user to a maximum of 2A. If you want to use 4A, you have to buy another one, which is a waste of money. Motech's intelligent power supply has automatic switching between High and Low Modes. When you want to use 4A, the voltage can be automatically expanded to 4A within 15V. One power supply can be used as two, which is economical and affordable.
3. RS-232 interface expansion: Power supplies with and without interfaces were originally two fields, and the design methods were also different. In order to seek economic benefits, increase competitiveness and ensure product quality, automated production testing is imperative.
Motech's digital power supply LPS series can be directly expanded to an RS-232 interface design. When you want to expand to a programmable power supply, the LPS series is what you want.
4. Single-step output function: In design and development or quality inspection, different voltage values ​​are often required to verify circuits or product components. For example, in the design of the commonly used voltage-frequency conversion circuit, whether the product is affected by different input voltages, the changes in the withstand voltage characteristics or voltage control characteristics of the components, etc.
In order to solve the problems faced by customers, Motech's digital power supply provides a single-step output function, with a minimum change of 10mV each time, such as: 12.34---->12.35---->12.36, to verify the linearity of the circuit or components.
5. True constant current source characteristics: General power supplies provide short-circuit protection function, but if the constant current source is used for a long time, there is a risk of burning the transistor. Motech's digital power supply provides a constant current operation mode (Constant Current Mode; CC), which can arbitrarily set the constant current value output, and can be used in factories such as electroplating plants that require constant current equipment.
6. Remote control (Remote Sensing)

As shown in the figure, assuming that the internal resistance of the wiring is 0.1, if 5A is produced, a voltage drop of 0.5V will be generated on each of the two lines, so that the original 10V output to the load is only 9V; to solve this problem, add +S and -S, connect one line to the load, and the voltage you set (10V) will be completely used on the load, and you don’t have to worry about the voltage drop caused by the internal resistance of the wiring. In addition, the low ripple and low noise power supply effect and load effect of less than 1mV are also the characteristics of this power supply. This is a top-selected power supply boutique and a favorite choice of experts.
7. External input control function: Use external input analog signals to change the output value. It is typically used in closed-loop control systems, such as constant temperature and constant humidity control.
8. Protection function:
a. Suppress the damage caused by instantaneous surges to the circuit: Most high-frequency components are easily burned by surge signals due to their low internal resistance. I believe that development engineers have similar experiences. The digital power supply of Motech Corporation is particularly output-prohibited when it is turned on, and the output is not generated until the user presses the output key. At this time, the damage to the circuit caused by the surge caused by the moment of power on is greatly reduced.
b. Voltage confirmation protection function: The biggest disadvantage of the power supply adjusted by the potentiometer is that if the potentiometer is accidentally touched when it is turned on, the voltage will also change. How many engineers have burned the circuit due to "carelessness", affecting efficiency. After the digital power supply of Motech Company is turned on, the voltage output can be confirmed, and it can be turned on if there is no problem, thereby protecting the user's circuit.
C. Short circuit protection: When short-circuited, the Motech power supply automatically enters the constant current source mode and issues an alarm to remind the user to check whether the line is connected incorrectly, while protecting the power supply.
D. Overvoltage and overcurrent protection: If the LPS series digital power supply is set beyond the rated value, the machine will refuse to accept the command and remind the user that it is an "input error" to protect the power supply.

Figure 1 Various voltage and current combinations at maximum power level Maintaining constant voltage or constant current

In the constant voltage (CV) mode of operation, the power supply will adjust its output current as needed to maintain the output voltage you set. This feature compensates for changes in load resistance, ensuring that you get the voltage level you need without having to constantly monitor and adjust the power supply's output.
In the figure, Vset is the desired voltage set on the front panel. In the CV mode of operation, the power supply adjusts Iset along the CV operating line as required to maintain Vset (at operating point 1, the power supply is in CV operating mode).
The constant current (CC) mode of operation works in the same way: the power supply adjusts Vset along the CC operating line as required to maintain Iset (at operating point 2, the power supply is in CC operating mode).