Product Description
MZ11-06A300-600RM and MZ11-10A300-600RM PTC thermistor is a protection component used in 485 communication interface evolved from the program-controlled security unit for program-controlled switches. The product is connected in series with the 485 communication interface, which can effectively prevent the interface from being damaged when the 220V mains is introduced into the communication line due to accidental damage or man-made damage, and can also appropriately reduce the impact of lightning inductance on the interface. This product has the characteristics of small steady-state resistance, low rated current, high withstand voltage capability and fast response speed. It is an economical and suitable choice for realizing 485 communication interface protection. Its application principle is shown in the figure below: In normal communication state, the product is equivalent to a current limiting resistor connected in series in the line, and the resistance value does not change. When abnormal overvoltage occurs, the TVS tube will be broken down, and the voltage will be reduced. The 485 communication interface is protected by being clamped. At this time, a large current passes through the PTC thermistor, so that its resistance changes in a stepwise manner, rising by 4-5 orders of magnitude and showing a high resistance state to achieve the purpose of protection. After the overvoltage disappears, the PTC thermistor will return to its initial state without affecting the communication function.
Application
For the 485 chip with overvoltage function, our company recommends using a PTC thermistor string A line or B line, and the TVS tube is connected between A and B after the thermal.
For the 485 chip without safety function, our company recommends using two PTC thermistors in series A line and B line, and then two TVS tubes are connected to the ground.
In some industrial sites, there are three 485 communication lines (A, B, ground) that are led out together, our company recommends that you connect to configure protection.
Our company has the following four general models for the overvoltage protection of the 485 communication interface, all of which are suitable for the normal working requirements of the ambient temperature below 75 °C.
| Marking | Withstand level | P/N |
| MZ6 | Anti-220V voltage | MZ11-06A300-600RM MZ11-06A500-800RM |
| MZ9 | Anti-380V voltage | MZ11-10A300-600RM MZ11-10A500-800RM |
. For some occasions with high lightning protection requirements, users can consider adding gas discharge tube protection. For 220V and 380V circuits, it is recommended to use 400V and 800V voltage levels.
Specification
Dimension Of PTC Thermistor
| Dmax | 10.50 |
| Hmax | 14.00 |
| Lmin | 5.00 |
| W±1 | 5.00 |
| Tmax | 5.00 |
| d±0.05 | 0.60 |
Electrical properties
| Item | Standard |
| Rated zero power resistance value | (30~60) ±2% |
| Non-action current | 20mA
R/Rn≤20% |
| Action current | 150mA
R/Rn≤20% |
| Max operating voltage | 450VAC
R/Rn≤30% |
| Curie temperature | 83±7ºC |
| Recovery time | t≤90S |
| Color | Green |
