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Distributed-Load Backplane Switching Characteristics

From Output

Under Test

Test

Point

1.5 V

19

Ω

Drvr

1.5 V

0.25”

2”

1”

1”

1.5 V

1”

1”

2”

0.25”

Rcvr

Rcvr

Rcvr

Slot 1

Slot 2

Slot 9

Slot 10

Conn.

Conn.

Conn.

Conn.

Switching Characteristics

SN74GTLPH306

8-BIT LVTTL-TO-GTLP BUS TRANSCEIVER

SCES284E – OCTOBER 1999 – REVISED APRIL 2005

The preceding switching characteristics table shows the switching characteristics of the device into a lumped

load (Figure 1). However, the designer's backplane application probably is a distributed load. The physical

representation is shown in Figure 2. This backplane, or distributed load, can be approximated closely to a

resistor inductance capacitance (RLC) circuit, as shown in Figure 3. This device has been designed for optimum

performance in this RLC circuit. The following switching characteristics table shows the switching characteristics

of the device into the RLC load, to help the designer better understand the performance of the GTLP device in

this typical backplane. See www.ti.com/sc/gtlp for more information.

Figure 3. Medium-Drive RLC Network

Figure 2. Medium-Drive Test Backplane

over recommended ranges of supply voltage and operating free-air temperature,

V

FROM

TO

PARAMETER

UNIT

(INPUT)

(OUTPUT)

3.6

A

B

ns

4.1

4.4

OE

B

ns

4.6

Rise time, B outputs (20% to 80%)

1.2

ns

Fall time, B outputs (80% to 20%)

2.2

ns

(1)

8