SN54LVTH18502A
SN54LVTH18502A is 3.3-V ABT SCAN TEST DEVICES manufactured by Texas Instruments.
description
The ’LVTH18502A and ’LVTH182502A scan test devices with 18-bit universal 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.
Additionally, these devices are designed specifically for low-voltage (3.3-V) VCC operation, but with the capability to provide a TTL interface to a 5-V system environment.
In the normal mode, these devices are 18-bit universal bus transceivers, that bine with D-type latches and D-type flip-flops, they allow data to flow in the transparent, latched, or clocked modes. Another use is 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 device operates in the transparent mode when LEAB is high. When LEAB is low, the A-bus data is latched while CLKAB is held at a static low or high logic level. Otherwise, if LEAB is low, A-bus data is stored on a low-to-high transition of CLKAB. When OEAB is low, the B outputs are active. When OEAB...
