DESCRIPTION
   The SP33 is a programmable RS-232 and/or RS-485 transceiver IC. The SP33 contains four drivers and four receivers when selected in RS-232 mode; and two drivers and two receivers when selected in RS-485 mode. The SP33 also contains a dual mode which has two RS-232 drivers/receivers plus one differential RS-485 driver/receiver. 

• +5V Only Operation
• Software Programmable RS-232 or RS-485
   Selection
• Four RS-232 Transceivers in RS-232 Mode
• Two RS-485 Full-Duplex Transceivers in
   RS-485 Mode
• Two RS-232 Transceivers and One RS-485
   Transceiver in Dual Mode
• Self-Testing Loopback Mode
• Full Driver Tri-State (Hi-Z) Control
• Ideal for RS-232 to RS-485 conversion