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

ESD Protection Exceeds JESD 22

– 2000-V Human-Body Model (A114-A)

– 200-V Machine Model (A115-A)

– 1000-V Charged-Device Model (C101)

Independent Register for A and B Buses

CY54FCT646T

– 48-mA Output Sink Current

– 12-mA Output Source Current

CY74FCT646T

– 64-mA Output Sink Current

– 32-mA Output Source Current

3-State Outputs

description

The ’FCT646T devices consist of a bus

transceiver circuit with 3-state, D-type flip-flops,

and control circuitry arranged for multiplexed

transmission of data directly from the input bus or

from the internal registers. Data on the A or B bus

is clocked into the registers as the appropriate

clock pin goes to a high logic level. Output-enable (G) and direction (DIR) inputs control the transceiver function.

In the transceiver mode,data present at the high-impedance port can be stored in either the A or B register, or

in both. Select controls (SAB, SBA) can multiplex stored and real-time (transparent mode) data. DIR determines

which bus receives data when G is low. In the isolation mode (G is high), A data can be stored in the B register

and/or B data can be stored in the A register.

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.