Help 485 chip is always broken down

ppr123

Help 485 chip is always broken down [Copy link]

 

The Max485 on my instrument communicates with a 485 chip (unknown model) in an external device, and the two chips are always broken down at the same time at irregular intervals.

bigbat

Add chip power supply diode clamp circuit and terminal resistor, and add TVS circuit to signal line

damiaa

If you need to add a protection circuit, at least add an SM712 or something like that.

If the product is to be used and connected to multiple units, it is best to add a gas discharge tube (GDT)

The specific circuit can be found on the Internet.

Otherwise, your 485 will do. It is not safe to travel alone at night after 12 o'clock.

surge

chunyang

This indicates that there is a problem with the circuit design. Let’s first give the current circuit.

chunyang

It is recommended to check out the old posts related to 485 on the site.

langtuodianzi

The figure below is the recommended RS485 typical application circuit diagram for reference.

damiaa

langtuodianzi published on 2023-7-11 15:36 The figure below is the recommended RS485 typical application circuit diagram for reference.

The one upstairs is a professional surge protector.

jinshan010

At least TVS should be added to the signal line

lanhua

"Two chips are broken down at the same time at irregular intervals"

Yesterday my 485 module was burned out due to a short circuit after the external line was disconnected.

一叶知秋霜

Whether the damage is in a strong interference environment, add a TVS tube to protect against static electricity and surges, and a small resistor can be connected in series on the AB line to suppress interference energy. AB should be reasonably designed for pull-up and pull-down, and the interference is large.

q1233

Add TVS tubes and discharge tubes. The key is to see what environment the application is in and choose the appropriate one.

mcu9651

To provide surge protection