ETL supports hot-plugging, VMEbus

Two new logic devices from Texas Instruments increase performance while maintaining compatibility with installed systems.

Two new Enhanced Transceiver Logic (ETL) bus interface devices can increase the performance of high-performance computer and communications systems, including those based on the VMEbus standard.

The devices also maintain compatibility with systems based on Transistor-to-Transistor Logic (TTL) bus interface devices.

The devices are able to reject much of the electrical noise commonly found in high-bandwidth systems. They also have high drive outputs, giving an ETL-based board the ability to switch a large electrical load on the incident transmission wave.

A bus-hold feature incorporated in the devices retains the last active state of the bus, eliminating the need for expensive, discrete pull-up resistors.

The SN74ABTE16245 and SN74ABTE16246 are available now from Texas Instruments and authorized distributors.

EPIC-IIB is a trademark of Texas Instruments Incorporated.

What is ETL?

Enhanced Transceiver Logic (ETL) provides an effective migration to the higher backplane bus bandwidth of VME64.

ETL-based backplanes support live insertion, or the ability to insert a non-powered board into a powered backplane with no effect on the active signals on the backplane. This is important for applications where the system must be in operation most, if not all, of the time-such as telecommunications switches, networking hubs and routers and high-availability minicomputers. Live insertion, also called "hot-plugging," allows the system to continue to function while boards are inserted and removed.

"Force Computers and the VME industry in general will be making a major push into telecommunications and other applications requiring high availability platforms. New ETL logic is a key enabling technology for this to happen. Without ETL, unpowered VME boards could not be inserted or removed from live VME64 backplanes," said Wayne Fisher, FORCE's director of strategic programs.

ETL also features very low capacitance, which reduces loading and transmission line effects.

Technical features

• Supports VME64 extensions specification, increasing bandwidth of VME-based systems by approximately 60 percent (40 MHz for ETL; 25 MHz for TTL)
• High-drive outputs (-60 to 90 milli-Amps) supports 25-ohm incident-wave switching
• Live insertion of ETL-based boards into live backplanes accomplished with Vcc BIAS pin, which assures precharged outputs between 1.3 and 1.7 V when Vcc not connected
• Operating temperature range from -40 to 85 degrees C
• EPIC-IIB BiCMOS fabrication process used to reduce power dissipation

ETL device availability and pricing

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SN74ABTE16245        16-bit switching      48-pin SSOP     $4.35

                     bus transceiver

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                     can be configured     48-pin TSSOP    $5.85

                     as two 8-bit or

                     one 16-bit transceiver

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SN74ABTE16246        8-bit open-collector   48-pin SSOP    $4.35

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                     3-bit tri-state        48-pin TSSOP   $5.85

                     control line

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Suggested resale pricing in U.S. dollars per unit in 1K quantity.

April 1995, vol. 11, no.1

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