SCEU023 October   2021

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Features
  3. 2Hardware
    1. 2.1 PCB Overview
    2. 2.2 Headers
    3. 2.3 Voltage Supply
    4. 2.4 Bypass Capacitors
    5. 2.5 OE Select
    6. 2.6 RC Loading
  4. 3Board Layout
  5. 4Schematic and Bill of Materials
    1. 4.1 Schematic
    2. 4.2 Bill of Materials

2.5 OE Select

A 3x1 100 mil header provides access to the Output Enable (OE) pins on the device. The 100 mil jumper is available for selecting a known state for the OE pin. The outer header pins access VCCA or VCCAB through a 10 kΩ resistor (0402). Because of VCC(MIN) circuitry, the OE pin on TXU device will defer to the lowest of the two supply voltages as reference for OE operation. The VCC(MIN) circuitry in conjunction with the over-voltage tolerant inputs allow the enable pin to be referenced to either VCCA or VCCAB.

An internal pull down resistor is present within the OE pin, allowing for the header to be disconnected without concern of the consequences of a floating CMOS input. Not pulling the OE to either VCCA or VCCAB will cause the OE pin to be pulled low and isolate your inputs from your outputs.

Figure 2-3 OE Pin Selection Jumper with Pullup Resistors