SCEU020B October   2019  – June 2021 TXS0101 , TXS0102 , TXS0104E , TXS0108E

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Features
      1. 1.1.1 TXS Family
    2. 1.2 Hardware Description
      1. 1.2.1 Headers
      2. 1.2.2 Voltage Supply
      3. 1.2.3 Bypass Capacitors
      4. 1.2.4 OE Select
      5. 1.2.5 RC Loading
  3. 2Board Layout
  4. 3Schematic and Bill of Materials
    1. 3.1 Schematic
    2. 3.2 Bill of Materials
  5. 4Revision History

1.1.1 TXS Family

The TXS family uses two separate configurable power supply rails VCCA and VCCB with A ports tracking the VCCA supply and B ports tracking the VCCB supply. These devices are fully specified for partial-power-down applications using IOFF. The IOFF circuitry (SCEA026) disables the outputs, preventing damaging current backflow through the device when it is powered down. The VCC isolation feature ensures that if either VCC supply is powered down (0V), then the I/O ports are in a high-impedance state.

The TXS family share the same architecture and one-shot circuitry for faster logic level transitions. In addition to the One-Shot circuitry, the TXS has a “weak-buffer” I/O structure which enables both slow speed open drain compatibility and higher speed push-pull operation up to 100 Mbps. TXS0101, TXS0102, and TXS0104E devices have a fixed internal 10 kΩ pull-up resistor on the I/O ports. The TXS0108E has smart pull-up resistors that switch between 4 kΩ when the output is driving a high and 40 kΩ when the output is driving a low. Refer to the application note A guide to voltage translation with the TXS family for more information on TXS family characteristics. Careful consideration should be taken when using external pull-up or pull-down resistors with TXS devices. Refer to the application note Effects of external pullup and pulldown resistors for further information.

Table 1-1 shows the comparison between the TXB, TXS and LSF Auto-Bidirectional families of TI.

Table 1-1 Auto-Bidirectional Families
MetricsTXBTXSLSF
Translation mechanismWeak buffered translationPassive translation with NMOS and internal pull-up resistorsPassive translation with NMOS and external pull-up resistors
Drive strengthVery low drive of 20ua due to 4K limiting bufferNo DC driveNo DC drive
Applications/ InterfacePush-pull applicationsOpen-drain applicationsPush-pull and open-drain applications
SpeedUp to 140MbpsUp to 24MbpsHigh speed up to 200Mbps
Translation flexibilityBuffered and fixed translation on A and B portsIntegrated pull-up resistors-reduces BOM cost of the system; Fixed translation on A and B portsFlexible translation due to external pull-up resistors
Frequency vs load balance trade-off
I/O portsA ports referenced to Vcca and B ports referenced to VccbA ports referenced to Vcca and B ports referenced to VccbA ports not referenced to Vcca, B ports not referenced to Vccb; allows multi-voltage translation
Edge- accelerationIntegrated one-shot edge acceleration circuitryIntegrated one-shot edge acceleration circuitryNo integrated one-shot acceleration circuitry
Vih/Vil requirementsDatasheet spec has Vih/Vil specificationsHas Vih /Vil spec but no RON for the FETNo Vih / Vil conditions, has RON specifications
Additional care-aboutVCCA<=VCCBVCCA<=VCCBVCCB>VCCA+0.8 V

Table 1-2 shows the packages supported by the TXS-EVM.

Table 1-2 TXS-EVM Packages and Devices supported
DevicePackagePinsDevice Populated
TXS0101DCK6Yes
TXS0102 (TXS0102-Q1)(1)DCU8Yes
TXS0104E (TXS0104E-Q1)(1)PW14Yes
TXS0108E (TXS0108E-Q1)(1)PW20No
RGY20Yes
(1) -Q1 devices are not populated on the EVM but are footprint compatible to the non -Q1 devices.
GUID-507A00C6-A6B8-4ABE-920B-AB5D10507DEC-low.gifFigure 1-1 TXS-EVM