This data sheet describes the features and functions of the SN54ABT18245A/SN74ABT18245A 18-bit bus transceiver scan test devices
The SN54ABT18245A and SN74ABT18245A are members of Texas Instruments' SCOPE™ testability family. They function as 18‑bit non‑inverting bus transceivers that can operate as two 9‑bit transceivers or a single 18‑bit transceiver. Data flow is controlled by DIR (direction) and OE (output‑enable) inputs, allowing bidirectional transfer between the A and B buses.
These devices support IEEE Standard 1149.1‑1990 boundary‑scan testing via a four‑wire TAP interface (TDI, TDO, TMS, TCK). In test mode, the normal bus operation is inhibited and the internal test circuitry can capture, shift, and update data registers, perform parallel‑signature analysis, and generate pseudo‑random patterns. The SN54ABT18245A is qualified for military temperature range 55 °C‑125 °C, while the SN74ABT18245A covers –40 °C‑85 °C.
| Operating temperature range (SN54ABT18245A) | 55 °C to 125 °C |
|---|---|
| Operating temperature range (SN74ABT18245A) | -40 °C to 85 °C |
| Instruction register length | 8 bits |
| Number of test‑data registers | 4 (44‑bit boundary‑scan, 3‑bit boundary‑control, 1‑bit bypass, 32‑bit device‑identification) |
It operates from 55 °C up to 125 °C.
The instruction register is 8 bits long.
The required pins are TDI, TDO, TMS, and TCK.
The instruction register resets to binary 10000001, which selects the IDCODE instruction.