Datasheet
7–131
Introduction
The purpose of this application report is to assist the designers of high- or low-performance digital logic systems in using the
Advanced System Logic (ASL) families: LV, LVC, LVT, ALVC, ABT, ABTE, ALB, GTL, FB, and CBT. A family
introduction, followed by a detailed comparison of the electrical characteristics, is provided to help designers understand the
differences between these products. In addition, typical data is provided to give the hardware designer a better understanding
of how these families operate under various conditions.
Device Family Overview
ABT Family
The ABT family is Texas Instruments (TI) second-generation family of BiCMOS bus-interface products. It is manufactured
using the latest 0.8-µ BiCMOS process, and provides high drive up to 64 mA and propagation delays below the 5-ns range,
while maintaining very low power consumption. ABT products are well suited for live-insertion applications with an I
off
specification of 0.1 mA. To reduce transmission-line effects, the ABT family has series-damping resistor options. Furthermore,
there are special ABT parts that provide extremely high-current drive (180 mA) to transmit down to 25-Ω transmission lines.
Advanced bus functions, such as universal bus transceivers (UBT), perform a wide variety of bus-interface functions.
Multiplexing options for memory interleaving and bus upsizing or downsizing also are provided. ABT devices are available
in octal, Widebus, or Widebus+. Widebus and Widebus+ packages feature higher performance with reduced noise and
flow-through pinout for easier board layout. In addition, Widebus+ devices have bus-hold circuitry on the inputs to eliminate
the need for external pullup resistors for floating inputs.
ABTE Family
ABTE provides wider noise margins and is backward-compatible with existing TTL logic. ABTE devices support the
VME64-ETL specification, with tight tolerances on skew and transition times. ABTE is manufactured using the latest 0.8-µ
BiCMOS process and provides high drive up to 90 mA. Other features include a bias pin and internal pullup resistors on control
pins for maximum live-insertion protection. Bus-hold circuitry eliminates external pullup resistors on the inputs and
series-damping resistors on the outputs damp reflections.
ALVC Family
The highest performance 3.3-V bus-interface family is the ALVC family. These specially designed 3-V products are processed
in 0.6-µ CMOS technology, giving typical propagation delays of less than 3 ns, along with current drive of 24 mA and static
power consumption of 40 µA for bus-interface functions. ALVC devices have bus-hold cells on inputs to eliminate the need
for external pullup resistors for floating inputs. The family also includes innovative functions for memory interleaving,
multiplexing, and interfacing to synchronous DRAMs. The ALVC family is available in the Widebus footprint with advanced
packaging, such as shrink small-outline package (SSOP) and thin shrink small-outline package (TSSOP).
CBT Family
In today’s computing market, power and speed are two of the main concerns. CBT addresses both of these issues in
bus-interface applications. CBT enables a bus-interface device to function as a very fast bus switch, effectively isolating buses
when the switch is open, and causing very little propagation delay when the switch is closed. These devices function as
high-speed bus interfaces between computer-system components such as the central processing unit (CPU) and memory. CBT
devices also can be used as 5-V to 3.3-V translators, allowing designers to mix 5-V or 3.3-V components in the same system.
CBT devices are available in advanced packaging, such as SSOP and TSSOP for reduced board area.