參數(shù)資料
型號(hào): SN74ABT8244
廠商: Texas Instruments, Inc.
英文描述: Scan Test Devices With Octal Buffers(掃描測試裝置(帶八緩沖器))
中文描述: 掃描測試設(shè)備與八路緩沖器(掃描測試裝置(帶八緩沖器))
文件頁數(shù): 4/19頁
文件大小: 390K
代理商: SN74ABT8244
SN54ABT8244, SN74ABT8244
SCAN TEST DEVICES WITH OCTAL BUFFERS
SCBS485 – JULY 1994
3–4
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
test architecture
Serial-test information is conveyed by means of a 4-wire test bus or TAP, that conforms to IEEE Standard
1149.1-1990. Test instructions, test data, and test control signals all are passed along this serial-test bus. The
TAP controller monitors two signals from the test bus, namely TCK and TMS. The TAP controller extracts the
synchronization (TCK) and state control (TMS) signals from the test bus and generates the appropriate on-chip
control signals for the test structures in the device. Figure 1 shows the TAP-controller state diagram.
The TAP controller is fully synchronous to the TCK signal. Input data is captured on the rising edge of TCK and
output data changes on the falling edge of TCK. This scheme ensures data to be captured is valid for fully
one-half of the TCK cycle.
The functional block diagram illustrates the IEEE Standard 1149.1-1990 4-wire test bus and boundary-scan
architecture and the relationship among the test bus, the TAP controller, and the test registers. As illustrated,
the device contains an 8-bit instruction register and three test-data registers: an 18-bit boundary-scan register,
an 11-bit boundary-control register, and a 1-bit bypass register.
Test-Logic-Reset
Run-Test/Idle
Select-DR-Scan
Capture-DR
Shift-DR
Exit1-DR
Pause-DR
Update-DR
TMS = L
TMS = L
TMS = H
TMS = L
TMS = H
TMS = H
TMS = L
TMS = H
TMS = L
TMS = L
TMS = H
TMS = L
Exit2-DR
Select-IR-Scan
Capture-IR
Shift-IR
Exit1-IR
Pause-IR
Update-IR
TMS = L
TMS = L
TMS = H
TMS = L
TMS = H
TMS = H
TMS = L
TMS = H
TMS = L
Exit2-IR
TMS = L
TMS = H
TMS = H
TMS = H
TMS = L
TMS = H
TMS = L
TMS = H
TMS = H
TMS = H
TMS = L
Figure 1. TAP-Controller State Diagram
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SN54ABT8373 Scan Test Devices With Octal D-Type Latches(掃描測試裝置(帶八D鎖存器))
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