Datasheet
7–203
Table 3. Typical Strip-Line Characteristics
†
DIMENSIONS
LINE
CAPACITANCE
t
MAXIMUM NUMBER OF LOADS
(mils)
LINE
IMPEDANCE
CAPACITANCE
C
O
(pF/in )
t
pd
(ns/in )
GTL BTL
T H W
Z
O
(Ω)
C
O
(pF/in
.
)
(ns/in
.
)
L = 12 in. L = 16 in. L = 24 in.
1.5 6 20 27 6.67 0.18 10 8 12
1.5 6 15 32 5.83 0.186 11 9 14
1.5 10 20 34 5.58 0.189 11 9 14
1.5 12 20 37 4.75 0.176 12 11 16
1.5 10 15 40 4.67 0.187 13 11 16
1.5 12 15 43 4 0.172 13 12 18
1.5 20 20 44 4 0.176 13 12 18
1.5 20 15 51 3.5 0.179 14 13 19
1.5 30 20 55 3.25 0.179 14 13 20
1.5 30 15 61 2.92 0.178 15 14 21
†
The characteristic impedance of the strip line is based on the following:
er = 5, relative dielectric constant of the board material (G10 glass epoxy)
H = thickness of the insulation dielectric
T = cross-sectional length of the strip line
W = cross-sectional width of the strip line
Frequency of the signal on the backplane is 50 MHz.
Summary
Today’s high-speed backplane and point-to-point applications require devices that can provide high performance, excellent signal
integrity, and cost effectiveness. GTL and BTL transceivers are designed to meet these characteristics. Both transceiver families
show similar skew, slew rate, and SSN performance. BTL is generally used for heavily loaded backplanes (100-mA I
OL
) and for
frequencies less than 75 MHz. However, the laboratory data presented in this report show that GTL is more suitable for designs
that require high performance (up to 100 MHz for the GTL16612 and GTL16616 and 200 MHz for the GTL16622 and
GTL16923) and low power consumption at low cost and minimum board space.
References
1. Texas Instruments Incorporated, ABT Advanced BiCMOS Technology Data Book, 1994, literature number SCBD002B.
2. Texas Instruments Incorporated, “Package Thermal Considerations”, ABT Advanced BiCMOS Technology Data Book, 1994,
literature number SCBD002B, pg. 13–97.
3. Gunning, Bill; Yuan, Leo; Nguyen, Trung; Wong, Tony, GTL: A Low-Voltage Swing Transmission Line Transceiver,
March 15, 1991.
4. Texas Instruments Incorporated, Advanced Schottky Load Management, 1987, literature number SDAA006.