10 Power Supply Recommendations

The output-enable (OE) input circuit is designed so that it is supplied by V_CCA and when the OE input is high, all outputs are placed in the high-impedance state. To ensure the high-impedance state of the outputs during power up or power down, the OE input pin must be tied to V_CCA through a pullup resistor and must not be enabled until V_CCA and V_CCB are fully ramped and stable. The minimum value of the pullup resistor to V_CCA is determined by the current-sinking capability of the driver.

V_CCA or V_CCB can be powered up first. If the SN74LVCH8T245 is powered up in a permanently enabled state
(for example OE is always kept low), pullup resistors are recommended at the input. This ensures proper, glitch-free, power-up. For more information, see Designing with SN4LVCXT245 and SN74LVCHXT245 Family of Direction Controlled Voltage Translators/Level-Shifters. In addition, the OE pin may be shorted to GND if the application does not require use of the high-impedance state at any time.