SCEU012A April   2018  – July 2021 SN74AVC4T245 , SN74AVC4T245-Q1 , SN74AXC1T45 , SN74AXC8T245

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Features
    2. 1.2 Hardware Description
      1. 1.2.1 Headers
      2. 1.2.2 Bypass Capacitors
      3. 1.2.3 Pullup and Pulldown Resistors
      4. 1.2.4 SMB Connectors
  3. 2Board Layout
  4. 3Schematic and Bill of Materials
    1. 3.1 Schematic
    2. 3.2 Bill of Materials
  5. 4Revision History

1.2.3 Pullup and Pulldown Resistors

The direction control and output enable pins are the inputs for the devices and should never be left floating. The CMOS inputs must be held at a known state, either VCC or ground, to ensure proper device operation. Refer to Implications of Slow or Floating CMOS Inputs (SCBA004). The default state of the control input is referenced to VCCA using a 10-kΩ pullup resistor. There is also the option of connecting the inputs to ground using pulldown resistors, or directly to ground via jumper on the header pins.

Table 1-5 lists the pullup and pulldown resistors.

Table 1-5 Pullup and Pulldown Resistors
DevicePinPullupPulldown
One Channel DTQDIRR4R8
One Channel DEADIRR2R7
Four Channel RSV(1)DIR1R14R25
DIR2R13R26
1OENR12R23
2OENR18R24
Eight Channel RJW (2)DIR1R11R28
DIR2R10R27
OENR9R22
(1) Four channel considering SN74AVC4T245
(2) Eight channel considering SN74AXC8T245