Members of the Texas Instruments

SCOPE E Family of Testability Products

Members of the Texas Instruments

WidebusE Family

State-of-the-Art 3.3-V ABT Design Supports

Mixed-Mode Signal Operation (5-V Input

and Output Voltages With 3.3-V VCC)

Support Unregulated Battery Operation

Down to 2.7 V

Include D-Type Flip-Flops and Control

Circuitry to Provide Multiplexed

Transmission of Stored and Real-Time Data

Bus Hold on Data Inputs Eliminates the

Need for External Pullup/Pulldown

Resistors

B-Port Outputs of ’LVTH182652A Devices

Have Equivalent 25-W Series Resistors, So

No External Resistors Are Required

Compatible With the IEEE Std 1149.1-1990

(JTAG) Test Access Port and

Boundary-Scan Architecture

SCOPE Instruction Set

– IEEE Std 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 ’LVTH18652A and ’LVTH182652A scan test devices with 18-bit bus transceivers and registers are

members of the Texas Instruments (TI) SCOPE testability integrated-circuit family. This family of devices

supports IEEE Std 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.

Additionally, these devices are designed specifically for low-voltage (3.3-V) VCC operation, but with the

capability to provide a TTL interface to a 5-V system environment.

In the normal mode, these devices are 18-bit bus transceivers and registers that allow for multiplexed

transmission of data directly from the input bus or from the internal registers. They can be used either as two

9-bit transceivers or one 18-bit transceiver. 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 SCOPE bus transceivers

and registers.

Data flow in each direction is controlled by clock (CLKAB and CLKBA), select (SAB and SBA), and

output-enable (OEAB and OEBA) inputs. For A-to-B data flow, data on the A bus is clocked into the associated

registers on the low-to-high transition of CLKAB. When SAB is low, real-time A data is selected for presentation

to the B bus (transparent mode). When SAB is high, stored A data is selected for presentation to the B bus

(registered mode). When OEAB is high, the B outputs are active. When OEAB is low, the B outputs are in the

high-impedance state.

Control for B-to-A data flow is similar to that for A-to-B data flow but uses CLKBA, SBA, and OEBA inputs. Since

the OEBA input is active-low, the A outputs are active when OEBA is low and are in the high-impedance state

when OEBA is high. Figure 1 illustrates the four fundamental bus-management functions that can be performed

with the ’LVTH18652A and ’LVTH182652A.