GS1508-CTA [GENNUM]
HDTV Cable Driver; HDTV电缆驱动器
| 型号： | GS1508-CTA |
| 厂家： | 
GENNUM CORPORATION |
| 描述： | HDTV Cable Driver |
| 文件： | 总8页 (文件大小：118K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
™
HD-LINX GS1508
HDTV Cable Driver
PRELIMINARY DATA SHEET
FEATURES
DESCRIPTION
• SMPTE 292M compliant
The GS1508 is a first generation very high speed bipolar
integrated circuit designed to drive two 75Ω co-axial
cables. The GS1508 is a SMPTE 292M compliant cable
driver that directly interfaces with other Gennum HDTV
devices and can also be used as a general purpose high
speed cable driver.
• dual cable driving outputs optimized for driving data
up to 1.485Gb/s
• ±7% tolerance output
• >17dB output return loss
• minimum external components
The GS1508 features two complementary outputs whose
amplitude is controlled within a precise 7% variation. The
output amplitude can be varied by adjusting the RSET
resistor value.
• seamless interface with the HD-LINX™ family of
products
• low power
• standard packaging
The serial inputs can be AC coupled. The GS1508 is a low
power device that does not require external pull down
resistors. The GS1508 is packaged in an 8 pin SOIC and
operates from a single 5V power supply.
APPLICATIONS
1.485Gb/s HDTV Serial Digital Receiver Interfaces for:
Routers, Distribution Amplifiers, Switchers, and other
transmitting equipment.
ORDERING INFORMATION
PART NUMBER
GS1508-CKA
GS1508-CTA
PACKAGE
8 pin SOIC
TEMPERATURE
0°C to 70°C
8 pin Tape and Reel
0°C to 70°C
BANDGAP REFERENCE AND BIASING CIRCUIT
R
SET
SDI
SDI
SDO
SDO
INPUT
DIFFERENTIAL
PAIR
OUTPUT STAGE &
CONTROL
PATENT PENDING
BLOCK DIAGRAM
Revision Date: March 2000
Document No. 522 - 02 - 03
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
ABSOLUTE MAXIMUM RATINGS
TA = 25°C unless otherwise indicated
PARAMETER
VALUE
5.5V
Supply Voltage
Input Voltage Range (any input)
Operating Temperature Range
Storage Temperature
-0.3 to (VCC +0.3)V
0°C to 70°C
-65°C to 150°C
300mW
Power Dissipation
Lead Temperature (soldering, 10 sec)
Input ESD Voltage
260°C
2000V
DC ELECTRICAL CHARACTERISTICS
VCC = 5V, TA = 0°C to 70°C unless otherwise shown.
Specifications assume 800mV output amplitude level settings into end terminated 75Ω transmission lines. Data Rate = 1485Mb/s unless otherwise shown.
TEST
LEVEL
PARAMETER
Supply Voltage
CONDITIONS
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
VCC
PD
4.75
-
5.00
215
5.25
265
V
1
1
System Power
Consumption
Driving two
75Ω cables
mW
Supply Current
IS
-
43
-
54
mA
V
1
2
Common Mode Input
Voltage Range
VCM,IN
2.5+(VDIFF/2
)
VCC-(VDIFF/2)
Common Mode Output
Voltage Range
VCM,OUT
-
VCC-VOUT
-
V
2
AC ELECTRICAL CHARACTERISTICS
VCC = 5V, TA = 0°C to 70°C unless otherwise shown.
Specifications assume 800mV output amplitude levels into end terminated 75Ω transmission lines. Data Rate = 1485Mb/s unless otherwise shown.
TEST
LEVEL
PARAMETER
Serial Digital Rate
CONDITIONS
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
DC
1485
5
-
Mb/s
psRMS
mV
1
3
2
1
1
4
Additive Jitter
1485Mb/s
-
150
750
-
-
1
diff p-p
p-p
Differential Input
Differential Output
Output Rise/Fall Times
VDIFF
VOUT
tR, tF
-
800
850
250
30
800
120
15
mV
(20% - 80%)
ps
2
Mismatch in Output Rise/Fall
Times
-
ps
Overshoot
-
-
-
1
8
30
-
%
ps
dB
4
1
4
Duty Cycle Distortion
Output Return Loss
NOTES:
15
17
5MHz to 1485MHz
2
TEST LEVELS:
23
1. 100% tested at 25°C.
2. Guaranteed by design.
3. Correlated Value.
1. RMS additive jitter measured using Pseudo Random bit sequence (2 - 1).
2. Measured with Gennum Evaluation Board (EB1508).
4. Tested with EB1508
2
522 - 02 - 03
PIN CONNECTIONS
1
2
3
4
8
7
6
5
SDI
SDI
SDO
SDO
GND
GS1508
TOP
VIEW
V
EE
R
V
SET
CC
PIN DESCRIPTIONS
NUMBER
SYMBOL
SDI, SDI
VEE
TYPE
DESCRIPTION
Serial data inputs (non-inverting and inverting).
Most negative supply voltage.
1, 2
3
I
P
I
4
RSET
Output amplitude control resistor.
5
VCC
P
P
O
Most positive supply voltage.
6
GND
Not connected internally. Connect to Ground. Used for isolation.
Serial data outputs (non-inverting and inverting).
7, 8
SDO, SDO
INPUT / OUTPUT CIRCUITS
V
CC
5k
SDO
SDO
SDI
SDI
20k
+
-
R
SET
Fig. 1 (Pins 1 and 2)
Fig. 2 (Pins 7 and 8)
3
522 - 02 - 03
DETAILED DESCRIPTION
INPUT INTERFACING
SDI/SDI are high impedance differential inputs. (See
Figure 1 for equivalent input circuit).
Several conditions must be observed when interfacing to
these inputs:
1. The differential input signal amplitude must be between
150 and 800mVpp.
2. The common mode voltage range must be as specified
in the DC Characteristics table. For a 400mV input from
the GS1504 HD cable equalizer, this corresponds to a
common mode voltage range of between 2.7 and 4.8
volts.
3. For input trace lengths longer than approximately 1cm,
the inputs should be terminated as shown in the Typical
Application Circuit.
Fig. 3 Output Optimized for Waveform Symmetry
L=8.2nH, R=75 (Typical ORL=13.5dB)
The GS1508 inputs are self biased, allowing for simple AC
coupling to the device. For serial digital HDTV, a minimum
capacitor value of 4.7µF should be used to allow coupling
of pathological test signals.
recommended.
A tantalum capacitor is
OUTPUT INTERFACING
The GS1508 outputs are current mode, and will drive
800mV into a 75 ohm load. These outputs are protected
from accidental static damage with internal static protection
diodes.
The SMPTE 292M standard requires that the output of a
cable driver have a source impedance of 75Ω and a return
loss of at least 15dB between 5Mhz and 1.485GHz.
Fig. 4 Output Optimized for Return Loss
L=12nH, C=0.5pF, R=75 (Typical ORL=18dB)
In order for an HD SDI output circuit using the GS1508 to
meet this specification, the output circuit shown in the
Typical Application Circuit is recommended.
Figures 3 and 4 show the eye diagram of the GS1508
output for two different output compensation conditions.
Figure 4 shows the GS1508 output optimized for wideband
return loss of 18dB. Figure 3 shows the GS1508 output
optimized for output waveform symmetry. In this case the
output may not exhibit a return loss of 15dB.
The values of LCOMP and CCOMP will vary depending on PCB
layout, but typical values are 12nH and 0.5pF respectively.
The small value of CCOMP can be easily swamped by
parasitic PCB capacitance, so it is recommended that the
ground plane be removed under the GS1508 output
circuitry (see the Application Information section in this data
sheet for further details). A 4.7µF capacitor is used for AC
coupling the output of the GS1508. This value is chosen to
ensure that pathological signals can be coupled without a
significant DC component occurring.
When measuring return loss at the GS1508 output it is
necessary to take the measurement for both a logic high
and a logic low output condition. This is because the output
protection diodes act as a varactor (voltage controlled
capacitor) as shown in Figure 5.
Consequently, the output capacitance of the GS1508 is
dependent on the logic state of the output.
4
522 - 02 - 03
1.000
0.800
0.600
0.400
0.200
0.000
GS1508
SDO
SDO
0.0000
0.0050
0.0100
1 / R
0.0150
0.0200
0.0250
Fig. 5 Static Protection Diodes
(mho)
SET
OUTPUT RETURN LOSS MEASUREMENT
Fig. 6 GS1508 Output Amplitude vs. 1/RSET
TABLE 1: RSET vs VOUT
RSET
To perform a practical return loss measurement, it is
necessary to force the GS1508 output to a DC high or low
condition. The actual measured return loss will be based on
the outputs being static at VCC or VCC-1.6V. Under normal
operating conditions the outputs of the GS1508 swing
between VCC-0.4V and VCC-1.2V, so the measured value of
return loss will not represent the actual operating return
loss.
R
1/RSET
0.0020
0.0067
0.0133
0.0187
0.0231
OUTPUT SWING
0.095
500.0
150.0
75.0
0.298
0.575
A simple method of calculating the values of actual
operating return loss is to interpolate the two return loss
measurements. In this way, the values of return loss are
53.6
0.785
43.2
0.937
estimated at
VCC-0.4V and VCC-1.2V based on the
measurements at VCC and VCC-1.6V.
NOTE: For reliable operation of the GS1508 over the full
temperature range, do not use an RSET value below 49.9Ω.
The two values of return loss (high and low) will typically
differ by several decibels. If the measured return loss is RH
for logic high and RL for logic low, then the two values can
be interpolated as follows:
RIH = RH- (RH-RL)/4 and
RIL = RL+(RH-RL)/4
where RIH is the interpolated logic high value and RIL is the
interpolated logic low value.
For example, if RH = -18dB and RL = -14dB, then the
interpolated values are RIH = -17dB and RIL = -15dB.
OUTPUT AMPLITUDE ADJUSTMENT
The output amplitude of the GS1508 can be adjusted by
changing the value of the RSET resistor as shown in Figure 6
and Table 1. For an 800mVp-p output with a nominal 7%
tolerance, a value of 53.6% is required. A 1% SMT resistor
should be used.
The RSET resistor is part of the high speed output circuit of
the GS1508. The resistor should be placed as close as
possible to the RSET pin. In addition, PCB capacitance
should be minimized at this node by removing the PCB
groundplane beneath the RSET resistor and the RSET pin.
5
522 - 02 - 03
TYPICAL APPLICATION CIRCUIT
V
CC
75
C
L
COMP
100n
COMP
75
75
PECL INPUT
4µ7
+
1
2
3
4
8
7
6
5
SDI
SDI
SDO
SDO
GND
OUT
OUT
75
GS1508
+
V
L
EE
COMP
Z
Z
0
0
V
CC
4µ7
C
R
V
COMP
SET
CC
1n
All resistors in ohms,
all capacitors in farads,
unless otherwise shown.
53.6
0µ1
TABLE 2: Typical Application Circuit Component Values
COMPONENT
RSET
VALUE
53.6
COMMENT
For 800mV Output
For 50Ω PCB trace impedance
Z0
50Ω
LCOMP
12nH
0.5pF
Typical value. Component value will vary depending on PCB layout.
Typical value. Component value will vary depending on PCB layout.
CCOMP
APPLICATION INFORMATION
PCB LAYOUT
Special attention must be paid to component layout when
designing serial digital interfaces for HDTV. Figures 8
through 11 show the artwork for a four layer printed circuit
evaluation board for the GS1508. The schematic is shown in
Figure 7. An FR-4 dielectric can be used, however,
controlled impedance transmission lines are required for
PCB traces longer than approximately 1cm. Note the
following PCB artwork features used to optimize
performance:
PCB trace width for HD rate signals is closely matched to
SMT component width to minimize reflections due to
change in trace impedance
The PCB ground plane is removed under the GS1508
output components to minimize parasitic capacitance.
The PCB ground plane is removed under the GS1508 RSET
pin and resistor to minimize parasitic capacitance
Input and output BNC connectors are surface mounted in-
line to eliminate a transmission line stub caused by a BNC
mounting via High speed traces are curved to minimize
impedance changes due to change of PCB trace width.
6
522 - 02 - 03
GS1508 EVALUATION BOARD
V
CC
1µ
C1
TP1
C2 100n
C3 1n
TP2
V
CC
C16
1n
L2 10n
R9
C10
R12
50
R8
75
100n
R13
50
75
R7
75
C14
C11
U2
C17 0p5
J7
J4
1µ
SDI SDO
SDI SDO
4µ7
C12
EDGEMNT_BNC
EDGEMNT_BNC
L3 10n
R10
C13
J6
J5
V
GND
EE
V
4µ7
1µ
CC
C15
10n
EDGEMNT_BNC
R
V
EDGEMNT_BNC
SET CC
75
R11
53.6
C18 0p5
All resistors in ohms,
all capacitors in farads,
unless otherwise shown.
Fig. 7 Schematic Diagram for the GS1508 Evaluation Board
Fig. 8 Top Layer of EB1508 PCB Layout
Fig. 10 Ground Layer of EB1508 PCB Layout
Fig. 9 Power Layer of EB1508 PCB Layout
Fig. 11 Bottom Layer of EB1508 PCB Layout
7
522 - 02 - 03
PACKAGE DIMENSIONS
1.91
5.00 MAX.
MAX
1.27 MAX
0.49 MAX
5
4
8
1
0.25
4.0
6.20
MAX
MAX
MAX
0.25
MAX
=
=
=
0.60 MAX
3.81 ±0.05
3 spaces
8-pin SOIC
All dimensions are in millimetres
@ 1.27 ±0.05
CAUTION
ELECTROSTATIC
SENSITIVE DEVICES
DO NOT OPEN PACKAGES OR HANDLE
EXCEPT AT A STATIC-FREE WORKSTATION
REVISION NOTES:
DOCUMENT IDENTIFICATION
Updated ordering information; Replaced evaluation board diagrams;
Updated pin descriptions; Added note to Table 1.
PRELIMINARY DATA SHEET
This product is in production. Gennum reserves the right to make
changes to the product and to the documentation.
For the latest product information, visit www.gennum.com
GENNUM JAPAN CORPORATION
C-101, Miyamae Village, 2-10-42 Miyamae, Suginami-ku
Tokyo 168-0081, Japan
GENNUM CORPORATION
MAILING ADDRESS:
P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3
Tel. +1 (905) 632-2996 Fax. +1 (905) 632-5946
Tel. +81 (03) 3334-7700 Fax. +81 (03) 3247-8839
GENNUM UK LIMITED
SHIPPING ADDRESS:
970 Fraser Drive, Burlington, Ontario, Canada L7L 5P5
25 Long Garden Walk, Farnham, Surrey, England GU9 7HX
Tel. +44 (0)1252 747 000 Fax +44 (0)1252 726 523
Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement.
© Copyright August 1998 Gennum Corporation. All rights reserved. Printed in Canada.
522 - 02 - 03
8
相关型号：
©2020 ICPDF网 联系我们和版权申明