IEEE Std 1149.1 (JTAG) Boundary-Scan Test Device With Octal Buffers

IEEE Std 1149.1 (JTAG) Boundary-Scan Test Device With Octal Buffers - SN74BCT8244A


The 'BCT8244A scan test devices with octal buffers are members of the Texas Instruments SCOPETM 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 functionally equivalent to the 'F244 and 'BCT244 octal buffers. The test circuitry can be activated by the TAP to take snapshot samples of the data appearing at the device terminals or to perform a self test on the boundary-test cells. Activating the TAP in normal mode does not affect the functional operation of the SCOPETM octal buffers.

In the test mode, the normal operation of the SCOPETM octal buffers is inhibited and the test circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry can perform boundary-scan test operations, as described in IEEE Standard 1149.1-1990.

Four dedicated test terminals 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.

The SN54BCT8244A is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74BCT8244A is characterized for operation from 0°C to 70°C.


  • Members of the Texas Instruments SCOPETM Family of Testability Products
  • Octal Test-Integrated Circuits
  • Functionally Equivalent to 'F244 and 'BCT244 in the Normal-Function Mode
  • Compatible With the IEEE Standard 1149.1-1990 (JTAG) Test Access Port and Boundary-Scan Architecture
  • Test Operation Synchronous to Test Access Port (TAP)
  • Implement Optional Test Reset Signal by Recognizing a Double-High-Level Voltage (10 V) on TMS Pin
  • SCOPETM Instruction Set
    • IEEE Standard 1149.1-1990 Required Instructions, Optional INTEST, CLAMP and HIGHZ
    • Parallel-Signature Analysis at Inputs
    • Pseudo-Random Pattern Generation From Outputs
    • Sample Inputs/Toggle Outputs
  • Package Options Include Plastic Small-Outline (DW) Packages, Ceramic Chip Carriers (FK), and Standard Plastic and Ceramic 300-mil DIPs (JT, NT)


SCOPE is a trademark of Texas Instruments Incorporated.

View more

Parametrics Compare all products in Boundary Scan (JTAG) Logic

Technology Family
VCC (Min) (V)
VCC (Max) (V)
Bits (#)
Voltage (Nom) (V)
F @ Nom Voltage (Max) (Mhz)
ICC @ Nom Voltage (Max) (mA)
tpd @ Nom Voltage (Max) (ns)
Output Drive (IOL/IOH) (Max) (mA)
Operating Temperature Range (C)
SN74BCT8244A SN54BCT8244A
BCT    BCT   
4.5    4.5   
5.5    5.5   
8    8   
5    5   
70    70   
52    52   
8.5    8.5   
64/-15    64/-15   
Catalog    Military   
0 to 70    -55 to 125   
24SOIC    24CDIP

Other qualified versions of SN74BCT8244A

Version Part Number Definition
Military SN54BCT8244A QML certified for Military and Defense Applications

Featured tools and software