Function, Pinout, and Drive Compatible
With FCT and F Logic
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
3-State Outputs
ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 200-V Machine Model (A115-A)
– 1000-V Charged-Device Model (C101)
Separation Controls for Data Flow in Each
Direction
Back-to-Back Latches for Storage
CY54FCT543T
– 48-mA Output Sink Current
– 12-mA Output Source Current
CY74FCT543T
– 64-mA Output Sink Current
– 32-mA Output Source Current

description
The ’FCT543T octal latched transceivers contain two sets of eight D-type latches with separate latch-enable
(LEAB, LEBA) and output-enable (OEAB, OEBA) inputs for each set to permit independent control of input and
output in either direction of data flow. For data flow from A to B, for example, the A-to-B enable (CEAB) input
must be low in order 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 the LEAB signal puts the A latches in the storage mode and their outputs no longer
change with the A inputs. With CEAB and OEAB low, the 3-state B-output buffers are active and reflect the data
present at the output of the A latches. Control of data from B to A is similar, but uses CEBA, LEBA, and OEBA
inputs.
These devices are 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.