SN54ABT18640 Datasheet | Texas Instruments

description The ’ABT18640 scan test devices with 18-bit inverting bus transceivers are members of the Texas Instruments SCOPE™ testability integrated-circuit family. This family of devices supports IEEE Standard 1149.1-1990 boundary scan to facilitate testing of plex circuit-board assemblies. Scan access to the test circuitry is acplished via the 4-wire test access port (TAP) interface. SN54ABT18640 . . . WD PACKAGE SN74ABT18640 . . . DGG OR DL PACKAGE (TOP VIEW) 1DIR 1 1B1 2 1B2 3 GND 4 1B3 5 1B4 6 VCC 7 1B5 8 1B6 9 1B7 10 GND 11 1B8 12 1B9 13 2B1 14 2B2 15 2B3 16 2B4 17 GND 18 2B5 19 2B6 20 2B7 21 VCC 22 2B8 23 2B9 24 GND 25 2DIR 26 TDO 27 TMS 28 56 1OE 55 1A1 54 1A2 53 GND 52 1A3 51 1A4 50 VCC 49 1A5 48 1A6 47 1A7 46 GND 45 1A8 44 1A9 43 2A1 42 2A2 41 2A3 40 2A4 39 GND 38 2A5 37 2A6 36 2A7 35 VCC 34 2A8 33 2A9 32 GND 31 2OE 30 TDI 29 TCK In the normal mode, these devices are 18-bit inverting bus transceivers. 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™ bus transceivers. Data flow is controlled by the direction-control (DIR) and output-enable (OE) inputs. Data transmission is allowed from the A bus to the B bus or from the B bus to the A bus, depending on the logic level at DIR. OE can be used to disable the device so that the buses are effectively isolated. In the test mode, the normal operation of the SCOPE™ 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 can perform boundary-scan test operations according to the protocol described in IEEE Standard 1149.1-1990. Please be aware that an important notice concerning availability, standard warranty, and use in critical...