AN-5025 Datasheet, PDF (1/3 Pages) Fairchild Semiconductor – Applications Using the GTLP10B320

AN-5025
Fairchild Semiconductor
Application Note
February 2001
Revised February 2001
Applications Using the GTLP10B320
Abstract
The GTLP10B320 is a GTLP (Gunning Transceiver Logic
Plus) device that offers features specifically designed to
address unique applications issues. This device is an
important innovation in backplane drivers, allowing for split
TTL inputs and outputs as well as an internal feedback
path. These features can add to the performance and/or
diagnostic capabilities of a system.
Features
Independent TTL inputs and outputs on the new
GTLP10B320 add versatility to numerous GTLP applica-
tions. Current GTLP devices have an A Port for TTL input
and a B Port for GTLP output under A Port to B Port opera-
tion, and a B Port GTLP input with an A Port TTL output
under B Port to A Port operation. In some applications this
single-set bi-directional TTL I/O may be an inconvenient
feature. In these applications, it may be more convenient to
have independent inputs and outputs.
FIGURE 1. GTLP10B320 Logic Diagram
In many cases, designers put two lines in parallel forming
one node on each of the TTL input pins, allowing the TTL
driver to send data on one line and receive data on
another. Another configuration uses one GTLP device to
send data and another GTLP device to receive data, add-
ing size and cost to the project. In these configurations, the
GTLP10B320 can replace two current GTLP devices
where data throughput is not critical.
Another important feature of the GTLP10B320’s split input
is a feedback path to monitor the master inputs on the A
Port. This allows another device to receive the TTL feed-
back to ensure the correct data is being distributed to the
bus. This internal feedback path is selected with SEL set to
LOW. When SEL is LOW and no data is sent out onto the
backplane, OEB is HIGH or 3-stated and data is simply fol-
lowing the feedback path from the A Port to the C Port.
After confirming that the correct TTL data is at the A Port,
toggling OEB to LOW enables the GTLP B Port, and data
is released onto the backplane.
© 2001 Fairchild Semiconductor Corporation AN500540
www.fairchildsemi.com