Members of the Texas Instruments

SCOPEE Family of Testability Products

Members of the Texas Instruments

WidebusE Family

Compatible With the IEEE Standard

1149.1-1990 (JTAG) Test Access Port and

Boundary-Scan Architecture

UBT E (Universal Bus Transceiver)

Combines D-Type Latches and D-Type

Flip-Flops for Operation in Transparent,

Latched, or Clocked Mode

Bus Hold on Data Inputs Eliminates the

Need for External Pullup Resistors

B-Port Outputs of ’ABTH182504A Devices

Have Equivalent 25-W Series Resistors, So

No External Resistors Are Required

State-of-the-Art EPIC-IIB E BiCMOS Design

One Boundary-Scan Cell Per I/O

Architecture Improves Scan Efficiency

SCOPE E Instruction Set

– IEEE Standard 1149.1-1990 Required

Instructions and Optional CLAMP and

HIGHZ

– Parallel-Signature Analysis at Inputs

– Pseudo-Random Pattern Generation

From Outputs

– Sample Inputs/Toggle Outputs

– Binary Count From Outputs

– Device Identification

– Even-Parity Opcodes

Packaged in 64-Pin Plastic Thin Quad Flat

(PM) Packages Using 0.5-mm

Center-to-Center Spacings and 68-Pin

Ceramic Quad Flat (HV) Packages Using

25-mil Center-to-Center Spacings

description

The ’ABTH18504A and ’ABTH182504A scan test devices with 20-bit universal bus transceivers are members

of the Texas Instruments SCOPEE testability integrated-circuit family. This family of devices supports IEEE

Standard 1149.1-1990 boundary scan to facilitate testing of complex circuit-board assemblies. Scan access to

the test circuitry is accomplished via the 4-wire test access port (TAP) interface.

In the normal mode, these devices are 20-bit universal bus transceivers that combine D-type latches and D-type

flip-flops to allow data flow in transparent, latched, or clocked modes. The test circuitry can be activated by the

TAP to take snapshot samples of the data appearing at the device pins or to perform a self test on the

boundary-test cells. Activating the TAP in the normal mode does not affect the functional operation of the

SCOPEE universal bus transceivers.

Data flow in each direction is controlled by output-enable (OEAB and OEBA), latch-enable (LEAB and LEBA),

clock-enable (CLKENAB and CLKENBA), and clock (CLKAB and CLKBA) inputs. For A-to-B data flow, the

device operates in the transparent mode when LEAB is high. When LEAB is low, the A-bus data is latched while

CLKENAB is high and/or CLKAB is held at a static low or high logic level. Otherwise, if LEAB is low and

CLKENAB is low, A-bus data is stored on a low-to-high transition of CLKAB. When OEAB is low, the B outputs

are active. When OEAB is high, the B outputs are in the high-impedance state. B-to-A data flow is similar to

A-to-B data flow, but uses the OEBA, LEBA, CLKENBA, and CLKBA inputs.

In the test mode, the normal operation of the SCOPEE universal bus transceivers is inhibited, and the test

circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry

performs boundary-scan test operations according to the protocol described in IEEE Standard 1149.1-1990.

Four dedicated test pins observe and control the operation of the test circuitry: test data input (TDI), test data

output (TDO), test mode select (TMS), and test clock (TCK). Additionally, the test circuitry performs other testing

functions such as parallel-signature analysis (PSA) on data inputs and pseudo-random pattern generation

(PRPG) from data outputs. All testing and scan operations are synchronized to the TAP interface.

Improved scan efficiency is accomplished through the adoption of a one boundary-scan cell (BSC) per I/O pin

architecture. This architecture is implemented in such a way as to capture the most pertinent test data. A

PSA/COUNT instruction also is included to ease the testing of memories and other circuits where a binary count

addressing scheme is useful.

Active bus-hold circuitry holds unused or floating data inputs at a valid logic level.

The B-port outputs of ’ABTH182504A, which are designed to source or sink up to 12 mA, include 25-W series

resistors to reduce overshoot and undershoot.

The SN54ABTH18504A and SN54ABTH182504A are characterized for operation over the full military

temperature range of –55°C to 125°C. The SN74ABTH18504A and SN74ABTH182504A are characterized for

operation from –40°C to 85°C.