SN54LVT8996, SN74LVT8996

3.3-V 10-BIT ADDRESSABLE SCAN PORTS

MULTIDROP-ADDRESSABLE IEEE STD 1149.1 (JTAG) TAP TRANSCEIVERS

SCBS686A – APRIL 1997 – REVISED DECEMBER 1999

5

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

NAME

DESCRIPTION

A9–A0

Address inputs. The ASP compares addresses received via shadow protocol against the value at A9–A0 to determine address

match. The bit order is from most significant to least significant. An internal pullup at each A9–A0 terminal forces the terminal

to a high level if it has no external connection.

BYP

Bypass input. A low input at BYP forces the ASP into BYP or BYP/TRST status, depending on PTRST being high or low,

respectively. While BYP is low, shadow protocols are ignored. Otherwise, while BYP is high, the ASP is free to respond to

shadow protocols. An internal pullup forces BYP to a high level if it has no external connection.

CON

Connect indicator (output). The ASP indicates secondary-scan-port activity (resulting from BYP, BYP/TRST, MULTICAST, or

ON status) by forcing CON to be low. Inactivity (resulting from OFF, RESET, or TRST status) is indicated when CON is high.

GND

Ground

PTCK

Primary test clock. PTCK receives the TCK signal required by IEEE Std 1149.1-1990. The ASP always buffers PTCK to STCK.

Shadow protocols are received/acknowledged synchronously to PTCK and connect-status changes invoked by shadow

protocol are made synchronously to PTCK.

PTDI

Primary test data input. PTDI receives the TDI signal required by IEEE Std 1149.1-1990. During appropriate TAP states, the

ASP monitors PTDI for shadow protocols. During shadow protocols, data at PTDI is captured on the rising edge of PTCK. When

a valid shadow protocol is received in this fashion, the ASP compares the received address against the A9–A0 inputs. If the

ASP detects a match, it outputs an acknowledgment and then connects its primary TAP terminals to its secondary TAP

terminals. Under BYP, BYP/TRST, MULTICAST or ON status, the ASP buffers the PTDI signal to STDO. An internal pullup

forces PTDI to a high level if it has no external connection.

PTDO

Primary test data output. PTDO transmits the TDO signal required by IEEE Std 1149.1-1990. During shadow protocols, the

ASP transmits any required acknowledgment via the PTDO. The acknowledgment data output at PTDO changes on the falling

edge of PTCK. Under BYP, BYP/TRST, or ON status, the ASP buffers the PTDO signal from STDI. Under OFF, MULTICAST,

RESET, or TRST status, PTDO is at high impedance.

PTMS

Primary test mode select. PTMS receives the TMS signal required by IEEE Std 1149.1-1990. The ASP monitors the PTMS to

determine the TAP-controller state. During stable TAP states other than Shift-DR or Shift-IR (i.e., Test-Logic-Reset,

Run-Test-Idle, Pause-DR, Pause-IR) the ASP can respond to shadow protocols. Under BYP, MULTICAST, or ON status, the

ASP buffers the PTMS signal to STMS. An internal pullup forces PTMS to a high level if it has no external connection.

PTRST

Primary test reset. PTRST receives the TRST signal allowed by IEEE Std 1149.1-1990. The ASP always buffers PTRST to

STRST. A low input at PTRST forces the ASP to assume TRST or BYP/TRST status, depending on BYP being high or low,

respectively. Such operation also asynchronously resets the internal ASP state to its power-up condition. Otherwise, while

PTRST is high, the ASP is free to respond to shadow protocols. An internal pullup forces PTRST to a high level if it has no

external connection.

STCK

Secondary test clock. STCK retransmits the TCK signal required by IEEE Std 1149.1-1990. The ASP always buffers STCK from

PTCK.

STDI

Secondary test data input. STDI receives the TDI signal required by IEEE Std 1149.1-1990. Under BYP, BYP/TRST, or ON

status, the ASP buffers STDI to PTDO. An internal pullup forces STDI to a high level if it has no external connection.

STDO

Secondary test data output. STDO transmits the TDO signal required by IEEE Std 1149.1-1990. Under BYP, BYP/TRST,

MULTICAST, or ON status, the ASP buffers STDO from PTDI. Under OFF, RESET, or TRST status, STDO is at high impedance.

STMS

Secondary test mode select. STMS retransmits the TMS signal required by IEEE Std 1149.1-1990. Under BYP, MULTICAST,

or ON status, the ASP buffers STMS from PTMS. When disconnected (as a result of OFF status), STMS maintains its last valid

state until the ASP assumes BYP/TRST, RESET, or TRST status (upon which it is forced high) or the ASP again assumes BYP,

MULTICAST, or ON status.

STRST

Secondary test reset. STRST retransmits the TRST signal allowed by IEEE Std 1149.1-1990. The ASP always buffers STRST

from PTRST.

VCC

Supply voltage