Function and Pinout Compatible With FCT

and F Logic

25- Output Series Resistors to Reduce

Transmission-Line Reflection Noise

Reduced VOH (Typically = 3.3 V) Versions

of Equivalent FCT Functions

Edge-Rate Control Circuitry for

Significantly Improved Noise

Characteristics

Ioff Supports Partial-Power-Down Mode

Operation

Matched Rise and Fall Times

Fully Compatible With TTL Input and

Output Logic Levels

12-mA Output Sink Current

15-mA Output Source Current

Separation Controls for Data Flow in Each

Direction

Back-to-Back Latches for Storage

ESD Protection Exceeds JESD 22

– 2000-V Human-Body Model (A114-A)

– 200-V Machine Model (A115-A)

– 1000-V Charged-Device Model (C101)

3-State Outputs

description

The CY74FCT2543T octal latched transceiver contains two sets of eight D-type latches. Separate latch enable

(LEAB, LEBA) and output enable (OEAB, OEBA) inputs permit each latch set to have independent control of

inputting and outputting in either direction of data flow. For example, for data flow from A to B, the A-to-B enable

(CEAB) input must be low to enter data from A or to take data from B, as indicated in the function table. With

CEAB low, a low signal on the A-to-B latch enable (LEAB) input makes the A-to-B latches transparent; a

subsequent low-to-high transition of LEAB puts the A latches in the storage mode and their outputs no longer

change with the A inputs. With CEAB and OEAB both low, the 3-state B output buffers are active and reflect

data present at the output of the A latches. Control of data from B to A is similar, but uses CEAB, LEAB, and

OEAB inputs. On-chip termination resistors at the outputs reduce system noise caused by reflections. The

CY74FCT2543T can replace the CY74FCT543T to reduce noise in an existing design.

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.