Datasheet

SN54LVTH18504A, SN54LVTH182504A, SN74LVTH18504A, SN74LVTH182504A
3.3-V ABT SCAN TEST DEVICES
WITH 20-BIT UNIVERSAL BUS TRANSCEIVERS
SCBS667B – JULY 1996 – REVISED JUNE 1997
14
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
bypass scan
This instruction conforms to the IEEE Std 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 Std 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 Std 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 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.