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SN74ABT18502PMG4 数据表(PDF) 5 Page - Texas Instruments |
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SN74ABT18502PMG4 数据表(HTML) 5 Page - Texas Instruments |
5 / 30 page SN74ABT18502 SCAN TEST DEVICE WITH 18-BIT REGISTERED BUS TRANSCEIVER SCBS753 – FEBRUARY 2002 5 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 test architecture Serial test information is conveyed by means of a four-wire test bus or TAP that conforms to IEEE Std 1149.1-1990. Test instructions, test data, and test control signals are all passed along this serial test bus. The TAP controller monitors two signals from the test bus, namely TCK and TMS. The function of the TAP controller is to extract the synchronization (TCK) and state control (TMS) signals from the test bus and generate 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 that data to be captured is valid for fully one-half of the TCK cycle. The functional block diagram shows the IEEE Std 1149.1-1990 four-wire test bus and boundary-scan architecture and the relationship between the test bus, the TAP controller, and the test registers. As illustrated, the device contains an 8-bit instruction register (IR) and four test data registers (DRs): an 84-bit boundary-scan register (BSR), a 21-bit boundary-control register (BCR), a 1-bit bypass register, and a 32-bit device identification register (IDR). 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 |
类似零件编号 - SN74ABT18502PMG4 |
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类似说明 - SN74ABT18502PMG4 |
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