SN74LVTH16646 - 3.3 V ABT 16-Bit Bus Transceivers and Registers With 3-State Outputs

The 'LVTH16646 devices are 16-bit bus transceivers designed for low-voltage (3.3-V) V_CC operation, but with the capability to provide a TTL interface to a 5-V system environment.

These devices can be used as two 8-bit transceivers or one 16-bit transceiver. Data on the A or B bus is clocked into the registers on the low-to-high transition of the appropriate clock (CLKAB or CLKBA) input. Figure 1 illustrates the four fundamental bus-management functions that can be performed with the 'LVTH16646 devices.

Output-enable (OE\) and direction-control (DIR) inputs are provided to control the transceiver functions. In the transceiver mode, data present at the high-impedance port may be stored in either register or in both. The select-control (SAB and SBA) inputs can multiplex stored and real-time (transparent mode) data. The circuitry used for select control eliminates the typical decoding glitch that occurs in a multiplexer during the transition between stored and real-time data. DIR determines which bus receives data when OE\ is low. In the isolation mode (OE\ high), A data can be stored in one register and/or B data can be stored in the other register.

When an output function is disabled, the input function is still enabled and can be used to store and transmit data. Only one of the two buses, A or B, can be driven at a time.

Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors with the bus-hold circuitry is not recommended.

To ensure the high-impedance state during power up or power down, OE\ should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

These devices are fully specified for hot-insertion applications using I_off and power-up 3-state. The I_off circuitry disables the outputs, preventing damaging current backflow through the devices when they are powered down. The power-up 3-state circuitry places the outputs in the high-impedance state during power up and power down, which prevents driver conflict.

Products containing the "SN74LVTH16646" keyword are: SN74LVTH16646DGGR , SN74LVTH16646DGGR , SN74LVTH16646DGGRE4 , SN74LVTH16646DGGRG4 , SN74LVTH16646DL , SN74LVTH16646DL , SN74LVTH16646DLG4 , SN74LVTH16646DLG4 , SN74LVTH16646DLR , SN74LVTH16646DLR

• Members of the Texas Instruments Widebus™ Family
• State-of-the-Art Advanced BiCMOS Technology (ABT) Design for 3.3-V Operation and Low Static-Power Dissipation
• Support Mixed-Mode Signal Operation (5-V Input and Output Voltages With 3.3-V V_CC)
• Support Unregulated Battery Operation Down to 2.7 V
• Typical V_OLP (Output Ground Bounce) < 0.8 V at V_CC = 3.3 V, T_A = 25°C
• I_off and Power-Up 3-State Support Hot Insertion
• Bus Hold on Data Inputs Eliminates the Need for External Pullup/Pulldown Resistors
• Distributed V_CC and GND Pin Configuration Minimizes High-Speed Switching Noise
• Flowthrough Architecture Optimizes PCB Layout
• Latch-Up Performance Exceeds 500 mA Per JESD 17
• ESD Protection Exceeds JESD 22
  • 2000-V Human-Body Model (A114-A)
  • 200-V Machine Model (A115-A)

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