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SN54LVT18512 数据表(PDF) 2 Page - Texas Instruments |
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SN54LVT18512 数据表(HTML) 2 Page - Texas Instruments |
2 / 36 page SN54LVT18512, SN54LVT182512, SN74LVT18512, SN74LVT182512 3.3-V ABT SCAN TEST DEVICES WITH 18-BIT UNIVERSAL BUS TRANSCEIVERS SCBS711 – OCTOBER 1997 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 description (continued) In the normal mode, these devices are 18-bit universal bus transceivers that combine D-type latches and D-type flip-flops to allow data flow in transparent, latched, or clocked modes. 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 ™ universal bus transceivers. Data flow in each direction is controlled by output-enable (OEAB and OEBA), latch-enable (LEAB and LEBA), and clock (CLKAB and CLKBA) inputs. For A-to-B data flow, the devices operate in the transparent mode when LEAB is high. When LEAB is low, the A data is latched while CLKAB is held at a static low or high logic level. Otherwise, if LEAB is low, A data is stored on a low-to-high transition of CLKAB. When OEAB is low, the B outputs are active. When OEAB is high, the B outputs are in the high-impedance state. B-to-A data flow is similar to A-to-B data flow but uses the OEBA, LEBA, and CLKBA inputs. In the test mode, the normal operation of the SCOPE ™ universal bus transceivers is inhibited, and the test circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry performs boundary-scan test operations according to the protocol described in IEEE Std 1149.1-1990. Four dedicated test pins are used to observe and 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 B-port outputs of ’LVT182512, which are designed to source or sink up to 12 mA, include equivalent 25- Ω series resistors to reduce overshoot and undershoot. The SN54LVT18512 and SN54LVT182512 are characterized for operation over the full military temperature range of –55 °C to 125°C. The SN74LVT18512 and SN74LVT182512 are characterized for operation from –40 °C to 85°C. FUNCTION TABLE† (normal mode, each register) INPUTS OUTPUT OEAB LEAB CLKAB A B L L L X B0‡ L L ↑ LL L L ↑ HH L HX L L L HX H H H X X X Z † A-to-B data flow is shown. B-to-A data flow is similar but uses OEBA, LEBA, and CLKBA. ‡ Output level before the indicated steady-state input conditions were established |
类似零件编号 - SN54LVT18512 |
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类似说明 - SN54LVT18512 |
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