CY29FCT818T

DIAGNOSTIC SCAN REGISTER

WITH 3-STATE OUTPUTS

SCCS012B – MAY 1994 – REVISED NOVEMBER 2001

1

POST OFFICE BOX 655303

With FCT, F Logic, and AM29818

Equivalent FCT Functions

Significantly Improved Noise

Characteristics

Operation

Output Logic Levels

– 2000-V Human-Body Model (A114-A)

– 200-V Machine Model (A115-A)

– 1000-V Charged-Device Model (C101)

– 64-mA Output Sink Current

– 32-mA Output Source Current

– 20-mA Output Sink Current

– 3-mA Output Source Current

description

The CY29FCT818T contains a high-speed 8-bit general-purpose data pipeline register and a high-speed 8-bit

shadow register. The general-purpose register can be used in an 8-bit-wide data path for a normal system

application. The shadow register is designed for applications such as diagnostics in sequential circuits, where

it is desirable to load known data at a specific location in the circuit and to read the data at that location.

The shadow register can load data from the output of the device, and can be used as a right-shift register with

bit-serial input (SDI) and output (SDO), using DCLK. The data register input is multiplexed to enable loading

from the shadow register or from the data input pins, using PCLK. Data can be loaded simultaneously from the

shadow register to the pipeline register, and from the pipeline register to the shadow register, provided

setup-time and hold-time requirements are satisfied, with respect to the two independent clock inputs.

In a typical application, the general-purpose register in this device replaces an 8-bit data register in the normal

data path of a system. The shadow register is placed in an auxiliary bit-serial loop that is used for diagnostics.

During diagnostic operation, data is shifted serially into the shadow register, then transferred to the

general-purpose register to load a known value into the data path. To read the contents at that point in the data

path, the data is transferred from the data register into the shadow register, then shifted serially in the auxiliary

diagnostic loop to make it accessible to the diagnostics controller. This data then is compared with the expected

value to diagnose faulty operation of the sequential circuit.

preventing damaging current backflow through the device when it is powered down.

Copyright

 2001, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

D, P, Q, OR SO PACKAGE

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OE

DCLK

SDI

GND

MODE

SDO

PCLK

On products compliant to MIL-PRF-38535, all parameters are tested

unless otherwise noted. On all other products, production

processing does not necessarily include testing of all parameters.