八路寄存收发器与3态输出 OCTAL REGISTERED TRANSCEIVER WITH 3-STATE OUTPUTS
DESCRIPON/ORDERING INFORMATION
This octal registered transceiver is designed for 1.65-V to 3.6-V VCC operation.
The SN74LVC543A contains two sets of D-type latches for temporary storage of data flowing in either direction. Separate latch-enable LEAB or LEBA and output-enable OEAB or OEBA inputs are provided for each register to permit independent control in either direction of data flow.
The A-to-B enable CEAB input must be low to enter data from A or to output data from B. If CEAB is low and LEAB is low, the A-to-B latches are transparent; a subsequent low-to-high transition of LEAB places the A latches in the storage mode. With CEAB and OEAB both low, the 3-state B outputs are active and reflect the data present at the output of the A latches. Data flow for B to A is similar to that of A to B, but uses CEBA, LEBA, and OEBA.
This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down. To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
FEATURES
• Operates From 1.65 V to 3.6 V
• Inputs Accept Voltages to 5.5 V
• Max tpd of 7 ns at 3.3 V
• Typical VOLPOutput Ground Bounce
<0.8 V at VCC= 3.3 V, TA= 25°C
• Typical VOHVOutput VOH Undershoot
>2 V at VCC = 3.3 V, TA = 25°C
• Supports Mixed-Mode Signal Operation on All Ports 5-V Input/Output Voltage With 3.3-V VCC
• Ioff Supports Partial-Power-Down Mode Operation
• Latch-Up Performance Exceeds 250 mA Per JESD 17
