The power ground is mainly for the path taken by the power loop current. Generally, the current flowing through the power supply is large, and the signal ground is mainly for the return of the communication signal between the two chips or modules. Path, in general, the current flowing through the signal is very small. In fact, both are GND. The reason is that you want to understand that when you are laying PCB board, you must clearly understand the flow of power and signal return. Path, then consider how to avoid the power supply and signal sharing return path when laying out. If it is shared, it may cause a large current on the power ground to generate a voltage difference on the signal ground (can be explained as: the wire is impedance, just Very small resistance, but if the current flowing is large, it will also produce a potential difference on this wire, which is also called common impedance interference), so that the true potential of the signal ground is higher than 0V, if the potential of the signal ground When it is large, it may cause the signal to be high level, but it is misjudged as low level.
First, different grounding
Of course, the power supply is inherently unclean, and this avoids misjudging the signal due to interference. So take a little attention to both wiring, you can. Generally speaking, even if they are together, there will be no big problem because the threshold of the digital circuit is high. In addition to proper grounding design and installation, grounding of various signals must be performed correctly. In the control system, there are roughly the following ground lines:
1, digitally
Digital ground: Also called logical ground, is the zero potential of various switching (digital) signals.
2, analog ground
Analog ground: is the zero potential of various analog signals.
3, signal ground
Signal ground: Usually the ground of the sensor.
4, exchange place
AC ground: The ground of the AC power supply, which is usually the ground where noise is generated.
5, DC ground
DC ground: The ground of the DC power supply.
6, shielding ground
Shielding ground: also called the chassis ground, designed to prevent static induction and magnetic field induction.
Second, some views on the grounding problem
These ground wire treatments are an important issue in system design, installation, and commissioning. Here are some thoughts on the grounding problem:
1. The control system should be grounded at one point.
Under normal circumstances, the high-frequency circuit should be grounded at multiple points, and the low-frequency circuit should be grounded at one point. In the low-frequency circuit, the inductance between the wiring and the component is not a big problem. However, the interference of the loop formed by the ground has a great influence. Therefore, the grounding point is often used as a grounding point; but one-point grounding is not suitable for the high frequency because the high frequency At the time, the ground line has an inductance, which increases the impedance of the ground line, and inductive coupling between the lines. Generally speaking, the frequency is below 1MHz, and one point can be grounded; when it is higher than 10MHz, multi-point grounding is used; one point can be grounded between 1~10MHz, and multiple points can be grounded.
2. The ground and signal ground cannot be shared.
Since there are several mV or even a few V voltages between two points of a power ground, this is a very important interference for low level signal circuits and must be isolated and prevented.
3. Comparison of floating and grounding
The whole system is floating, that is, all parts of the system are floating with the earth. This method is simple, but the insulation resistance of the whole system and the earth cannot be less than 50MΩ. This method has a certain anti-interference ability, but it will cause interference once the insulation is lowered. Another method is to ground the case and leave the rest floating. This method is strong in anti-interference ability, safe and reliable, but it is complicated to implement.
4, analog ground
The connection of the analog ground is very important. In order to improve the anti-common mode interference capability, shielded floating technology can be used for analog signals. Grounding of specific analog signals should be designed in strict accordance with the requirements in the operation manual.
5, shielding ground
In the control system, in order to reduce the capacitive coupling noise in the signal, accurate detection and control, it is necessary to use shielding measures for the signal. Depending on the purpose of the shielding, the connection of the shielding ground is different. Electric field shielding solves the problem of distributed capacitance, generally connected to the earth; electromagnetic field shielding mainly avoids high-frequency electromagnetic field radiation interference such as radar and radio. Made of high-conductivity of low-resistance metal materials, it can be grounded. The magnetic field shielding is used to prevent magnetic induction of magnets, motors, transformers, coils, etc. The shielding method is to use a high magnetic conductive material to close the magnetic circuit, generally it is better to connect the earth. When the signal circuit is grounded at one point, the shield of the low frequency cable should also be grounded at one point.
If there is more than one shield location of the cable, a noise current will be generated, creating a source of noise interference. When a circuit has an ungrounded signal source connected to a grounded amplifier in the system, the shield at the input should be connected to the common terminal of the amplifier; conversely, when the grounded signal source is connected to an ungrounded amplifier in the system, the input to the amplifier The terminal should also be connected to the common end of the signal source.
For the grounding of electrical systems, it should be classified according to the requirements and purpose of grounding. It is not possible to simply and arbitrarily connect different types of grounding. Instead, it should be divided into several independent grounding subsystems, each with its common grounding point. Or ground the trunk, and finally connect together to implement the total grounding.
Hotel Door Lock Motor also known as Smart Hotel Door Lock Motor, perform operations in the hotel door lock, at this point, the cardholder simply throw the door handle to open the door. That is to say the hotel door lock motor is used to open the door.
Induction door lock is a infrared sensor through induction of new security equipment, widely used in hotels, hotels and clubs, and other areas of the smart IC card, rf door lock, generally divided into induction induction door lock system, provides the high quality for the hotel induction door lock system. Induction in the European and American countries have been developed to a certain extent, has been a measure of the quality of life index of height and life.
Operating temperature range:
Hotel door lock motor should be used at a temperature of -10~60℃.
The figures stated in the catalog specifications are based on use at ordinary room temperature catalog specifications re based on use at ordinary room temperature (approximately20~25℃.
If a Smart Hotel Door Lock Motor is used outside the prescribed temperature range,the grease on the gearhead area will become unable to function normally and the motor will become unable to start.Depending on the temperature conditions ,it may be possible to deal with them by changing the grease of the motor's parts.Please feel free to consult with us about this.
Storage temperature range:
lock motor should be stored ta a temperature of -15~65℃.
In case of storage outside this range,the grease on the gearhead area will become unable to function normally and the motor will become unable to start.
Service life:
The longevity of Smart Hotel Door Lock Motor is greatly affected by the load conditions , the mode of operation,the environment of use ,etc.Therefore,it is necessary to check the conditions under which the product will actually be used .The following conditions will have a negative effect on longevity.Please consult with us should any of them apply.
â—Use with a load that exceeds the rated torque
â—Frequent starting
â—Momentary reversals of turning direction
â—Impact loads
â—Long-term continuous operation
â—Forced turning using the output shaft
â—Use in which the permitted overhang load or the permitted thrust load is exceeded
â—A pulse drive ,e.g.,a short break,counter electromotive force,PWM control
â—Use of a voltage that is nonstandard as regards the rated voltage
â—Use outside the prescribed temperature or relative-humidity range,or in a special environment.
â—Please consult with us about these or any other conditions of use that may apply,so that we can be sure that you select the most appropriate model.
Hotel door lock motor applicable door types: building doors, fire doors, security doors, door and office door, fire doors, etc. Applicable scenario: family, company, office buildings, schools, shopping malls, such as Banks.
when it come to volume production,we're a major player as well .each month,we rurn out 600000 units,all of which are compliant with the rohs directive.Have any questions or special needed, please contact us, we have the engineer group and best sales department to service to you
Looking forward to your inquiry. Welcome to our factory.
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