SLLU356 September   2022 THVD1424

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Information on Cautions and Warnings
  5. 3Board Description
    1. 3.1 Board Component Overview
      1. 3.1.1 Powering the Boarde
        1. 3.1.1.1 Single Supply Operation
        2. 3.1.1.2 Dual Supply Operation (Separate Digital Logic and Driver supplies)
        3. 3.1.1.3 Default Operation Mode
        4. 3.1.1.4 Single Ended Bus Modification Operational Modes
  6. 4Design Documents
    1. 4.1 Schematics
    2. 4.2 Board Layout
    3. 4.3 Bill Of Materials
  7. 5Revision History

3.1.1.2 Dual Supply Operation (Separate Digital Logic and Driver supplies)

In Dual Supply operation the digital circuit supply, the supply which supplies the R, D, /RE, DE, H/F, SLR, TERM_RX, and TERM_TX, can be held at a lower level than the VCC voltage of 3 V to 5.5 V as it can go down to 1.65V. Allowing a 3.3V - 5V RS-485 bus to interface with devices operating at 1.8 V or 2.5 V logic. See Table 3-3 for information on power supply components in dual operation mode.

The VL supply is located at J6 on the bottom of the board and VCC is J5 located at the top of the board.

Table 3-3 Dual Supply Operation Configuration Table
Component ID Comment
J5 Connect to VL source (1.65V to 5.5V) for Logic Supply
J6 Connect to VCC Source (3V to 5.5V)
J7 Leave Open
C2, C3, C4, and/or C5 Have Minimum of 1uF of Decoupling Capacitance on VL
C6 and/or C8 If More Decoupling Capacitance is Desired Attach Capacitors to C6 and C8
R14 and/or R15 Install Resistor if Low impedance pathway between GND and EARTH is desired