Datasheet

SN74GTLPH16612
18-BIT LVTTL-TO-GTLP UNIVERSAL BUS TRANSCEIVER
SCES326C MARCH 2000 REVISED AUGUST 2001
3–220
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
DISTRIBUTED-LOAD BACKPLANE SWITCHING CHARACTERISTICS
The previous switching characteristics table shows the switching characteristics of the device into a lumped load
(Figure 1). However, the designers 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 an 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.
Drvr
1.5 V
.25” 2”
1” 1”
1.5 V
1”1”
2” .25”
Rcvr
Rcvr
Rcvr
Figure 2. Medium-Drive Test Backplane
Slot 1 Slot 2 Slot 9 Slot 10
Conn.
Conn. Conn. Conn.
Z
O
= 70
38
38
From Output
Under Test
Test
Point
1.5 V
C
L
= 9 pF
19
L
L
= 19 nH
Figure 3. Medium-Drive RLC Network
switching characteristics over recommended ranges of supply voltage and operating free-air
temperature, V
TT
= 1.5 V and V
REF
= 1 V for GTLP (see Figure 3)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
MIN TYP
UNIT
f
max
85 MHz
t
PLH
3.6
t
PHL
A B
3.6
ns
t
PLH
4.3
t
PHL
LEAB B
4.3
ns
t
PLH
4.4
t
PHL
CLKAB B
4.4
ns
t
en
4.1
t
dis
OEAB
B
4.3
ns
t
r
Rise time, B outputs (20% to 80%) 1.4 ns
t
f
Fall time, B outputs (80% to 20%) 2.1 ns
All typical values are at V
CC
= 3.3 V, T
A
= 25°C. All values are derived from TI SPICE models.