Post Go back to editing

Questions about using MAX3485 and MAX3088 together

Category: Hardware
Product Number: MAX3485, MAX3088
Software Version: .

Our company is using it for RS-485 communication.
1) MAX3088 uses existing mass-produced products
2) Scheduled to be changed to MAX3485 for new mass production

For the reasons above, please answer the following three questions.

1. Mixed use of MAX3088 and MAX3485.
 - Existing products use MAX3088 for RS-485 communication.
 - Additional production products use the MAX3485 for RS-485 communication.
 - When using mixed products, check if there are any abnormalities.

2. Whether to remove the terminating resistor.
 - The length of the line using RS-485 Max. Within 100M.
 - Connected products max. Within 7 devices.
 - Termination resistance 110Ω is connected to each product.
 - As a result of the current test, if a product is added to the RS-485 line, the RS-485 communication voltage level is low.

3. Combination of RS-485 A/B line protection circuit.
 - Existing products have 485 A-line pull-down and 485 B-line pull-up applied.
 - 485 -> 4 of 1N4148WS (switch diode) is applied to 485 A/B Line 1st Fix due to poor communication. (VCC/GND line)
 - 2 SM712-02HTG(TVS) 485 A/B Line applied -> 2nd correction due to poor communication of 485 ground line)
 - When using mixed using protect diode, check if there are any abnormalities.

Please reply to confirm whether it is applicable to mass production.

Thank you