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These bus buffers are designed specifically for low-voltage (3.3-V) V_CC operation, but with the capability to provide a TTL interface to a 5-V system environment.

The ’LVTH125 devices feature independent line drivers with 3-state outputs. Each output is in the high-impedance state when the associated output-enable (OE) input is high.

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.

When V_CC is between 0 and 1.5 V, the devices are in the high-impedance state during power up or power down. However, to ensure the high-impedance state above 1.5 V, 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.