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)

CY54FCT157T

– 32-mA Output Sink Current

– 12-mA Output Source Current

CY74FCT157T

– 64-mA Output Sink Current

– 32-mA Output Source Current

3-State Outputs

description

The ’FCT157T devices are quad two-input multiplexers that select four bits of data from two sources under the

control of a common data-select (S) input. The output-enable (E) input is active low. When E is high, all of the

outputs (Y) are forced low, regardless of all other input conditions.

Moving data from two groups of registers to four common output buses is a common use of the ’FCT157T

devices. The state of S determines the particular register from which the data comes. It also can be used as

a function generator. These devices are useful for implementing highly irregular logic by generating any 4 of

the 16 different functions of 2 variables, with 1 variable common.

The ’FCT157T devices are logic implementations of a four-pole, two-position switch, where the position of the

switch is determined by the logic levels at S.

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.