SN54LVTH18504A, SN54LVTH182504A, SN74LVTH18504A, SN74LVTH182504A
3.3-V ABT SCAN TEST DEVICES
WITH 20-BIT UNIVERSAL BUS TRANSCEIVERS
SCBS667B – JULY 1996 – REVISED JUNE 1997
Members of the Texas Instruments
SCOPE Family of Testability Products
Compatible With the IEEE Std 1149.1-1990
(JTAG) Test Access Port and
Boundary-Scan Architecture
Members of the Texas Instruments
Widebus Family
SCOPE Instruction Set
– IEEE Std 1149.1-1990 Required
Instructions and Optional CLAMP and
HIGHZ
– Parallel-Signature Analysis at Inputs
– Pseudo-Random Pattern Generation
From Outputs
State-of-the-Art 3.3-V ABT Design Supports
Mixed-Mode Signal Operation (5-V Input
and Output Voltages With 3.3-V V
)
CC
Support Unregulated Battery Operation
Down to 2.7 V
UBT (Universal Bus Transceiver)
Combines D-Type Latches and D-Type
Flip-Flops for Operation in Transparent,
Latched, or Clocked Mode
– Sample Inputs/Toggle Outputs
– Binary Count From Outputs
– Device Identification
– Even-Parity Opcodes
Bus Hold on Data Inputs Eliminates the
Need for External Pullup/Pulldown
Resistors
Packaged in 64-Pin Plastic Thin Quad Flat
(PM) Packages Using 0.5-mm
Center-to-Center Spacings and 68-Pin
Ceramic Quad Flat (HV) Packages Using
25-mil Center-to-Center Spacings
B-Port Outputs of ’LVTH182504A Devices
Have Equivalent 25-Ω Series Resistors, So
No External Resistors Are Required
description
The ’LVTH18504A and ’LVTH182504A scan test devices with 20-bit universal bus transceivers are members
of the Texas Instruments (TI) SCOPE testability integrated-circuit family. This family of devices supports
IEEE Std 1149.1-1990 boundary scan to facilitate testing of complex circuit-board assemblies. Scan access to
the test circuitry is accomplished via the 4-wire test access port (TAP) interface.
Additionally, these devices are designed specifically for low-voltage (3.3-V) V
capability to provide a TTL interface to a 5-V system environment.
operation, but with the
CC
In the normal mode, these devices are 20-bit universal bus transceivers that combine D-type latches and D-type
flip-flops to allow data flow in transparent, latched, or clocked modes. 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),
clock-enable (CLKENAB and CLKENBA), 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
CLKENAB is high and/or CLKAB is held at a static low or high logic level. Otherwise, if LEAB is low and
CLKENAB 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 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, CLKENBA, and CLKBA inputs.
Inthetestmode, thenormaloperationoftheSCOPEuniversalbustransceiversisinhibited, andthetestcircuitry
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.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SCOPE, UBT, and Widebus are trademarks of Texas Instruments Incorporated.
Copyright 1997, Texas Instruments Incorporated
UNLESS OTHERWISE NOTED this document contains PRODUCTION
DATA information current as of publication date. Products conform to
specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all
parameters.
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