GENLINX
™
II
GS9028 Cable Driver
with Two Adjustable Outputs
DATA SHEET
FEATURES
• SMPTE 259M compliant
• two complementary outputs, adjustable from 50 to
1000mVp-p into 75Ω loads
• operational from DC to 622Mb/s
• nominal 470ps rise and fall times
• < ±7% output amplitude control
• 45% system power reduction over the GS9008
• no external pulldown resistors required
• input hysteresis
• operational down to 80mV input amplitude
• operates from a single +5 or -5 volt supply
• 8 pin SOIC
APPLICATIONS
4ƒsc, 4:2:2, and 4:4:4:4 serial digital video interfaces from
143Mb/s to 540Mb/s; general purpose high speed cable
driver applications.
The GS9028 consumes 45% less system power than the
GS9008 and does not require external pulldown resistors
resulting in a smaller PCB footprint. Operational with input
amplitudes as low as 80mV, the GS9028 is a robust serial
interface device.
The GS9028 is packaged in an 8 pin SOIC and operates
from a single +5 or -5 volt supply.
ORDERING INFORMATION
PART NUMBER
GS9028-CKA
GS9028-CTA
PACKAGE
8 pin SOIC
8 pin SOIC Tape
TEMPERATURE
0°C to 70°C
0°C to 70°C
DESCRIPTION
The GS9028 is a second generation bipolar integrated
circuit designed to drive two 75Ω co-axial cables.
GS9028
The GS9028 features two complementary outputs whose
amplitude is controlled within ± 7%. The output signal levels
are also adjustable from as low as 50mV to as high as
1000mV with little change in other performance parameters.
The output amplitude of the output stage is varied by
adjusting the R
SET
resistor value.
BANDGAP REFERENCE AND BIASING CIRCUIT
R
SET
SDI
SDI
INPUT
DIFFERENTIAL
PAIR WITH
HYSTERESIS
OUTPUT STAGE
& RISE/FALL TIME
CONTROL CIRCUIT
SDO
SDO
BLOCK DIAGRAM
Revision Date: April 2000
GENNUM CORPORATION P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3
Tel. +1 (905) 632-2996 Fax. +1 (905) 632-5946 E-mail: info@gennum.com
www.gennum.com
Document No. 521 - 68 - 04
ABSOLUTE MAXIMUM RATINGS
T
A
= 25°C unless otherwise specified
PARAMETER
Supply Voltage
Input Voltage Range (any input)
VALUE
5.5V
-0.3 to (V
CC
+0.3)V
0 to 70°C
-65 to 150°C
260°C
GS9028
Operating Temperature Range
Storage Temperature
Lead Temperature (soldering, 10 sec)
DC ELECTRICAL CHARACTERISTICS
V
CC
= 5V, T
A
= 0°C to 70°C unless otherwise shown. Specifications assume 800mV output amplitude levels into end terminated 75Ω transmission lines.
PARAMETER
Supply Voltage
System Power
Consumption
Supply Current
Common Mode Input
Voltage Range
Differential Input
Common Mode
Output Voltage Range
Differential Output
Input Hysteresis
SYMBOL
V
CC
P
D
Ι
S
V
CM,IN
V
DIFF
V
CM,OUT
V
OUT
CONDITIONS
MIN
4.75
TYP
5.00
165
MAX
5.25
195
UNITS
V
mW
NOTES
TEST
LEVEL
1
3
Driving two 75Ω
cables
-
-
2.4+(V
DIFF
/2)
80
-
33
-
39
V
CC
-(V
DIFF
/2)
1000
-
mA
V
3
2
-
V
CC
-V
OUT
800
-
mV
V
2
2
R
SET
= 59Ω
750
10
850
-
mV
mV
1
2
AC ELECTRICAL CHARACTERISTICS
V
CC
= 5V, T
A
= 0°C to 70°C unless otherwise shown. Specifications assume 800mV output amplitude levels into end terminated 75Ω transmission lines.
PARAMETER
Serial Data Rate
Additive Jitter
SYMBOL
CONDITIONS
MIN
0
TYP
-
25
25
50
470
50
MAX
622
-
-
-
700
100
UNITS
Mb/s
ps p-p
NOTES
TEST
LEVEL
1
270Mb/s
540Mb/s
622Mb/s
-
-
-
400
-
1
2
Output Rise/Fall Time
Mismatch in Output
Rise/Fall Times
Overshoot
Duty Cycle Distortion
Output Return Loss
TEST LEVELS
1. 100% tested at 25°C.
2. Guaranteed by design.
3. Correlated value.
t
R
, t
F
20% - 80%
ps
ps
3
1
-
-
540MHz
NOTES
-
5
50
17
8
100
-
%
ps
dB
2
1
2
1. RMS additive jitter measured using Pseudo Random bit sequence (2
23
- 1).
2. Measured with Gennum Evaluation Board (EB-RD35).
2
521 - 68 - 04
PIN CONNECTIONS
SDO
SDO
V
EE
R
SET
8
V
CC
SDI
SDI
1
2
7
GS9028
3 TOP VIEW 6
4
5
GS9028
V
EE
PIN DESCRIPTIONS
NUMBER
1
2
4
6
7
SYMBOL
SDO
SDO
R
SET
SDI
SDI
TYPE
O
O
I
I
I
Serial data output (inverse).
Serial data output.
Output amplitude control resistor.
Serial data input (inverse).
Serial data input.
DESCRIPTION
INPUT/OUTPUT CIRCUITS
V
CC
SDO
SDO
SDI
SDI
+
-
R
SET
Fig. 1 Input Circuit (pins 6 and 7)
Fig. 2 Output Circuit (pins 1 and 2)
3
521 - 68 - 04
TYPICAL PERFORMACE CURVES
(measured using the Typical Application Circuit)
GS9028
Fig. 3 Output Eye Diagram 270Mb/s
Fig. 4 Output Eye diagram 540Mb/s
Fig. 5 Output Eye Diagram 622Mb/s
4
521 - 68 - 04
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
1000mV.
2. The common mode voltage range must be as specified
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.
Figures 6 and 7 illustrate two methods of interfacing the
GS9028 to the Gennum GS9024 (Cable Equalizer), GS9035
(Reclocker) or the GS9025 (Receiver).
Figure 6 illustrates the simplest interface and is
recommended when the trace lengths between the driver
and the GS9028 are less than 0.5in. The pull up resistors
should be placed near the GS9028 to serve as end
terminations.
V
CC
10nF
+
_
V
CC
100nF
10nF
75Ω
75Ω
75Ω
75Ω
+
_
GS9028
GS9028
GS9024 or
GS9035 or
GS9025
Fig. 7
The GS9028 can also be configured to accept ac coupled
input signals. In this case, the inputs must be dc biased as
illustrated in Figure 8.
V
CC
10nF
R1
1µF
R1
+
_
1µF
R2
75Ω
+
_
GS9024 or
GS9035 or
GS9025
75Ω
+
_
GS9028
GS9028
R2
Fig. 8
The recommended values for R1 and R2 are:
R1 = 1.35Z
O
Fig. 6
R2 = 3.85Z
O
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 impedance traces and source and end
terminations should be used as shown in Figure 7. Although
terminations on both sides reduce the signal swing by a
factor of two, the GS9028 is designed to meet this need
with ultra low input amplitude requirements (as low as
80mV). This low input amplitude requirement also allows the
use of 50Ω transmission lines (which are more robust and
easier to control in multilayer boards) to interconnect the
GS9024/25/35 and the GS9028.
where Z
O
is the transmission line characteristic impedance.
For 75Ω cable, R1 = 100Ω and R2 = 287Ω.
OUTPUT INTERFACING
Figure 9 illustrates the recommended interface for ac
coupled outputs.
V
CC
10nF
R
T
= R = Z
O
R
R
T
+
GS9028
R
T
L
L
R
1µF
1µF
_
GS9028
Fig. 9
5
521 - 68 - 04
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