GS9029 ETC, GS9029 Datasheet - Page 6

• Manufacturer Part Number: GS9029
• Description: GENLINX GS9029 Quad Output Serial Digital Video Cable Driver
• Manufacturer: ETC

DETAILED DESCRIPTION
INPUT INTERFACING
SDI/SDI are high impedance differential inputs. Two
conditions must be observed when interfacing to these
inputs:
1. The input signal amplitude must be between 80mV and
2. The common mode voltage range must be as specified
Figures 6 and 7 illustrate two methods of interfacing the
GS9029 to the Gennum GS9024 (Cable Equalizer), GS9035
(Reclocker) or the GS9025 (Receiver).
Figure
recommended when the trace lengths between the driver
and the GS9029 are less than 0.5 in.
When trace lengths become longer than 0.5in. and data
rates greater than 360Mb/s, electromagnetic reflections
begin to affect signal integrity. To minimize reflections,
controlled
terminations should be used as shown in Figure 7. Although
terminations on both sides reduce the signal swing by a
factor of two, the GS9029 is designed to meet this need
with ultra low input amplitude requirements (as low as
80mV).
The GS9029 can accept AC coupled input signals with no
extra configuration required.
521 - 97 - 02
1000mV.
in the DC Characteristics Table (page 2). For 800mV
input amplitude signals, this corresponds to a common
mode voltage range between 2.8 and 4.6 volts.
Fig. 6 Interfaces using Internal SDI Terminations
Fig. 7 Interfaces using Internal SDI Terminations
6
impedance
illustrates
+
_
+
_
Connected to AC Ground
10nF
75
V
10nF
the
CC
SDI/T
traces
+
_
75
GS9029
+
_
GS9029
GS9028
simplest
V
and
10nF
CC
SDI/T
SDI/T
SDI/T
interface
source
and
and
end
is
6
OUTPUT INTERFACING
Figure 8 illustrates the recommended interface for ac
coupled outputs.
The termination resistor (R
characteristic
impedance traces should be used for the outputs and the
termination resistors should be placed near the GS9029.
The inductor (L) and resistor (R) are used to optimize the
output return loss and are PCB dependent. Typically, R
equals the transmission line characteristic impedance and
L is approximately 8.2nH.
OUTPUT AMPLITUDE ADJUSTMENT
The GS9029 outputs are adjustable from as low as 50mV to
as high as 1000 mV. The output amplitudes are set by the
R
between the approximate output amplitude (V
is given by the equation below:
where Z
The minimum value of R
800mV output amplitudes, the value of R
note that the above formula assumes that the transmission
line is properly end terminated.
SET0
and the R
O
is in ohms and V
Fig. 8 Interfaces for AC Coupled Outputs
GS9029
+
GS9028
_
impedance
SET1
10nF
R
R
T
resistors respectively. The relationship
SET
V
CC
SET
=
OUT
T
R
) value should be equal to the
1.154 Z
---------------------------- -
T
2
is 43.2 . For 75
of
is in volts.
V
OUT
R
the
L
R
L
R
T
O
= R = Z
1µF
1µF
cable.
SET
O
is 54.9 . Also,
OUT
cable and
Controlled
) and R
SET