SN54LVT18502

3.3-V ABT SCAN TEST DEVICE

WITH 18-BIT UNIVERSAL BUS TRANSCEIVERS

SCBS669 – JULY 1996

13

POST OFFICE BOX 655303

bypass scan

This instruction conforms to the IEEE Standard 1149.1-1990 BYPASS instruction. The bypass register is

selected in the scan path. A logic 0 value is captured in the bypass register during Capture-DR. The device

operates in the normal mode.

control boundary to high impedance

This instruction conforms to the IEEE Standard 1149.1a-1993 HIGHZ instruction. The bypass register is

selected in the scan path. A logic 0 value is captured in the bypass register during Capture-DR. The device

operates in a modified test mode in which all device I/O pins are placed in the high-impedance state, the device

input pins remain operational, and the normal on-chip logic function is performed.

control boundary to 1/0

This instruction conforms to the IEEE Standard 1149.1a-1993 CLAMP instruction. The bypass register is

selected in the scan path. A logic 0 value is captured in the bypass register during Capture-DR. Data in the I/O

BSCs for pins in the output mode is applied to the device I/O pins. The device operates in the test mode.

boundary-run test

The bypass register is selected in the scan path. A logic 0 value is captured in the bypass register during

Capture-DR. The device operates in the test mode. The test operation specified in the BCR is executed during

Run-Test /Idle. The five test operations decoded by the BCR are: sample inputs/toggle outputs (TOPSIP),

PRPG, PSA, simultaneous PSA and PRPG (PSA/PRPG), and simultaneous PSA and binary count up

(PSA/COUNT).

boundary read

The BSR is selected in the scan path. The value in the BSR remains unchanged during Capture-DR. This

instruction is useful for inspecting data after a PSA operation.

boundary self test

The BSR is selected in the scan path. All BSCs capture the inverse of their current values during Capture-DR.

In this way, the contents of the shadow latches can be read out to verify the integrity of both shift-register and

shadow-latch elements of the BSR. The device operates in the normal mode.

boundary toggle outputs

The bypass register is selected in the scan path. A logic 0 value is captured in the bypass register during

Capture-DR. Data in the shift-register elements of the selected output-mode BSCs is toggled on each rising

edge of TCK in Run-Test /Idle and is then updated in the shadow latches and thereby applied to the associated

device I/O pins on each falling edge of TCK in Run-Test /Idle. Data in the input-mode BSCs remains constant.

Data appearing at the device input or I/O pins is not captured in the input-mode BSCs. The device operates in

the test mode.

boundary-control-register scan

The BCR is selected in the scan path. The value in the BCR remains unchanged during Capture-DR. This

operation must be performed before a boundary-run test operation to specify which test operation is to

be executed.