SN74AXCH1T45 - Single-bit dual-supply bus transceiver

The SN74AXCH1T45 is a single-bit noninverting bus transceiver that uses two individuallyconfigurable power-supply rails. The device is operational with both V_CCAand V_CCB supplies as low as 0.65 V. The A port is designed to trackV_CCA, which accepts any supply voltage from 0.65 V to 3.6 V. The B port isdesigned to track V_CCB, which also accepts any supply voltage from 0.65 V to3.6 V. Additionally the SN74AXCH1T45 is compatible with a single-supply system.

The DIR pin determines the direction of signal propagation. With the DIR pin configuredHIGH, translation is from Port A to Port B. With DIR configured LOW, translation is from Port B toPort A. The DIR pin is referenced to V_CCA, meaning that its logic-high andlogic-low thresholds track with V_CCA.

Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use ofpullup or pulldown resistors with the bus-hold circuitry is not recommended. If a supply is presentfor V_CCA or V_CCB, the bus-hold circuitry alwaysremains active on the A or B inputs respectively, independent of the state of the direction controlpin.

This device is fully specified for partial-power-down applications using theI_off current. The I_off protection circuitry ensuresthat no excessive current is drawn from or to an input, output, or combined I/O that is biased to aspecific voltage while the device is powered down.

The V_CC isolation feature ensures that if eitherV_CCA or V_CCB is less than 100 mV, both I/O portsenter a high-impedance state by disabling their outputs.

Glitch-free power supply sequencing allows either supply rail to be powered on or off inany order while providing robust power sequencing performance.

• Fully Configurable Dual-Rail Design Allows Each Port to Operate With a Power Supply Range from 0.65 V to 3.6 V
• Operating Temperature: –40°C to +125°C
• Glitch-Free Power Supply Sequencing
• Bus-hold on Data Inputs Eliminates the Need for External Pullup or Pulldown Resistors
• Maximum Quiescent Current (I_CCA + I_CCB) of 8 µA (85°C Maximum) and 14 µA (125°C Maximum)
• Up to 500-Mbps Support When Translating from 1.8 to 3.3V
• V_CC Isolation Feature
  • If Either V_CC Input is Below 100 mV, All I/Os Outputs are Disabled and Become High-Impedance
• I_off Supports Partial-Power-Down Mode Operation
• Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
• ESD Protection Exceeds JESD 22
  • 8000-V Human Body Model
  • 1000-V Charged-Device Model

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