Description
1 Introduction
Homyet Parts offers a wide range of switch products. These products are used for many applications to simply open and close electronic circuits.
The switching function is mainly mechanical, but many switches are operating like an analog-digital interface for modern electronic circuits, with clearly defined voltage levels for logic 0 and logic 1. But anyone who has built an application with a tact or detector switch with a fast responding electronic circuit may be wondering why the circuit is not working properly. The reason may be what is called contact bouncing (also known as chattering). There are possibilities to eliminate the effects of this phenomena and this application note proposes a circuit to avoid this common issue.
2 What is contact bounce
We naturally have the impression that the contact in a switch is immediate and firm. Figure 2: Idealized graph of a switched signal However, the "reality" looks a little bit different.
At each switch position, contact between electrically conductive points is established or separated by means of movable mechanical elements.Typically, spring components are used as transmitters of the nominal state, either as a metal plate or as a coiled spring, which have a certain mass and thus a certain moment of inertia. When these small components are set in motion for a change of state, they are accelerated until they have reached the desired position. There, they experience a reverse acceleration due to the principles of elastic shock and their spring characteristics. This effect occurs several times in succession until the movement is completely damped. As the damping factor is high and the moment of inertia is small, the effect itself typically only takes a few microseconds. This is not problematic for power circuits but this rebounding signal on status change creates bad transitions for a digital input. During the status change, the electronic signal has an unstable or better said undefined status. For a logic IC this can be really problematic, as it needs a clean defined signal. A microcontroller reading the port may miss the changed state if read at the wrong moment. Therefore a solution is needed to generate a clear output from the switch and we will take a look at a switch debounce circuit to solve this problem.
| Product Name: | Tact Switch Serise |
| Rating: | DC 12V 50mA Max |
| Contact Resistance: | ≤100mΩ |
| Insulation Resistance: | ≥100MΩ |
| Operating Temperature: | -20ºC~+70ºC |
| Travel: | 0.2±0.1mm; 0.25±0.1mm and etc. |
| Operating Force: | 100gf±50gf, 130gf±50gf, 160gf±50gf, 180gf±50gf, 200gf±50gf, 250gf±50gf |
| Compressive Strength: | 100V AC for 50Hz/1min |
| Lifetime: | 50,000cycles or 100,000cycels |
| Material: | NYLON/PBT/LCP/PA66/Copper |
| MOQ: | 1000Pcs |
| Packing: | Bag Packing or Reel&tape Packing
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Q: Are your a trading company or factory?
A: We are the manufacturer, we establish in 2008, have more than 10 years experiences in this field.
Q: Do you provide samples?
A: Yes,we could offer the sample for free charge but do not pay the cost of freight.
Q: What is the MOQ for your products ?
A: The MOQ of most of our product is 1000pcs
Q: Do you provide customized services?
A: Yes,we support OEM/ODM service.
Q: When will you ship the goods out if i send payment now?
A: Usually,our lead time is 7 days after payment recevied.
Q: Is there quality control on all production lines?
A: Yes, all production lines have adequate quality control.
Q: What is your terms of payment?
A: We accept Multiple payment methods such us T/T in advance,Paypal, L/C and so on.
Q: How do you arrange the shipment?
A: We can provide multiple modes of transportation, such as by express(DHL,FedEx,UPS,TNT etc), by sea and by air.
Q: What is your after-sales service?
A: We provide return and exchange service for quality problems caused by non-human factors, and we will pay the freight. We assist in solving any product technical problems throughout the process.
Complaint
