SN75HVD08DG4 datasheet by Texas Instruments

SN75HVD08DG4 Frequently Asked Questions (FAQs)

• What is the maximum cable length supported by the SN75HVD08DG4?
  The maximum cable length supported by the SN75HVD08DG4 depends on the baud rate and the type of cable used. As a general rule, the maximum cable length is around 100 meters at 9600 bps and 10 meters at 115200 bps. However, it's recommended to consult the RS-485 standard and perform signal integrity analysis to determine the maximum cable length for a specific application.
• How do I configure the SN75HVD08DG4 for half-duplex or full-duplex operation?
  The SN75HVD08DG4 is a half-duplex transceiver, meaning it can only transmit or receive at a time. To configure it for half-duplex operation, connect the DE (driver enable) pin to the RE (receiver enable) pin. For full-duplex operation, use two separate transceivers, one for transmission and one for reception.
• What is the minimum input voltage required for the SN75HVD08DG4 to operate?
  The minimum input voltage required for the SN75HVD08DG4 to operate is 3.0V. However, it's recommended to operate the device at a minimum of 3.3V to ensure reliable operation and to meet the RS-485 standard.
• Can I use the SN75HVD08DG4 in a 5V system?
  Yes, the SN75HVD08DG4 can be used in a 5V system, but it's recommended to use a voltage regulator to regulate the supply voltage to 3.3V or 3.0V to ensure reliable operation and to meet the RS-485 standard.
• How do I terminate the RS-485 bus to prevent signal reflections?
  To terminate the RS-485 bus, connect a 120-ohm resistor between the A and B lines at the end of the bus. This will prevent signal reflections and ensure reliable operation. Additionally, it's recommended to use a termination network consisting of a 120-ohm resistor and a 220-ohm resistor in series to provide additional signal integrity.