GS1508_10 [GENNUM]
HDTV Cable Driver; HDTV电缆驱动器
| 型号： | GS1508_10 |
| 厂家： | 
GENNUM CORPORATION |
| 描述： | HDTV Cable Driver |
| 文件： | 总14页 (文件大小：722K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
GS1508 HD-LINX™ HDTV Cable Driver
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, with
amplitudes 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
Pb-free and Green
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.
Applicatons
•
1.485Gb/s HDTV Serial Digital Receiver Interfaces for:
Routers, Distribution Amplifiers, Switchers, and other
transmitting equipment
Bandgap Reference
and Biasing Circuit
R
SET
SDI
SDI
SDO
SDO
Input
Differential
Pair
Output Stage
and Control
Patent Pending
Figure A: Block Diagram
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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1. Pin Out
1.1 Pin Assignment
SDI
SDI
1
2
3
4
8
7
6
5
SDO
SDO
GND
GS1508
(top
view)
V
EE
R
V
SET
CC
Figure 1-1: Pin Assignment
1.2 Pin Descriptions
Table 1-1: Pin Descriptions
Pin Number
Symbol
Type
Description
1, 2
3
SDI, SDI
VEE
Input
Power
Input
Serial data inputs (non-inverting and inverting).
Most negative supply voltage.
4
RSET
Output amplitude control resistor.
5
VCC
Power
Power
Output
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
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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2. Electrical Characteristics
2.1 Absolute Maximum Ratings
Table 2-1: Absolute Maximum Ratings
T
= 25°C unless otherwise indicated
A
Parameter
Value
Supply Voltage
5.5V
Input Voltage Range (any input)
-0.3 to (V +0.3)V
CC
Operating Temperature Range
Storage Temperature
0°C to 70°C
-65°C to +150°C
300mW
Power Dissipation
Lead Temperature (soldering, 10 sec)
Input ESD Voltage
260°C
2000V
2.2 DC Electrical Characteristics
Table 2-2: DC Electrical Characteristics
V
= 5V, T = 0°C to 70°C unless otherwise shown.
A
CC
Specifications assume 800mV output amplitude level settings into end terminated 75Ω transmission lines. Data Rate = 1485Mb/s unless
otherwise shown.
Test
Level
Parameter
Condition
Symbol
Min
Typ
Max
Units
Notes
Supply Voltage
—
V
4.75
—
5.00
215
5.25
V
—
—
1
1
CC
System Power
Consumption
Driving two
75Ω cables
P
265
mW
D
Supply Current
—
—
I
—
43
—
54
mA
V
—
—
1
2
S
Common Mode
Input Voltage
Range
V
2.5+(V
)
V
-(V
)
DIFF/2
CM,IN
DIFF/2
CC
Common Mode
Output Voltage
Range
—
V
—
V
-V
CC OUT
—
V
—
2
CM,OUT
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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2.3 AC Electrical Characteristics
Table 2-3: AC Electrical Characteristics
V
= 5V, T = 0°C to 70°C unless otherwise shown.
A
CC
Specifications assume 800mV output amplitude level settings into end terminated 75Ω transmission lines. Data Rate = 1485Mb/s unless
otherwise shown.
Test
Level
Parameter
Condition
Symbol
Min
Typ
Max
Units
Notes
Serial Digital
—
—
DC
1485
—
Mb/s
—
1
Rate
Additive Jitter
1485Mb/s
—
—
—
5
—
ps
1
3
2
RMS
Differential
Input
150
—
800
mV
diff
p-p
Differential
Output
—
(20% to 80%)
—
750
—
800
120
15
850
250
30
mV
ps
p-p
2
1
1
4
Output Rise/Fall
Times
Mismatch in
Output Rise/Fall
Times
—
—
ps
—
Overshoot
—
—
—
—
—
—
1
8
%
ps
—
—
4
1
Duty Cycle
15
30
Distortion
Output Return
Loss
5MHz to
1485MHz
—
—
17
—
dB
2
4
NOTES:
23
1. RMS additive jitter measured using Pseudo Random bit sequence (2 - 1).
2. Measured with Gennum Evaluation Board (EB1508).
Test Levels:
1. 100% tested at 25°C.
2. Guaranteed by design.
3. Correlated value.
4. Tested with EB1508.
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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3. Detailed Description
3.1 Input Interfacing
SDI/SDI are high-impedance differential inputs (see Figure 4-1 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 Electrical
Characteristics table. For a 400mV input from the GS1504 HD cable equalizer, this
corresponds to a common mode voltage range of between 2.7V and 4.8V.
3. For input trace lengths longer than approximately 1cm, the inputs should be
terminated as shown in the Typical Application Circuit.
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. A tantalum capacitor is recommended.
3.2 Output Interfacing
The GS1508 outputs are current-mode, and will drive 800mV into a 75Ω 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.
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.
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.
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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Figure 3-1: Output Optimized for Waveform Symmetry, L=8.2nH, R=75Ω
(Typical ORL=13.5dB)
Figure 3-2: Output Optimized for Return Loss, L=12nH, C=0.5pF, R=75Ω
(Typical ORL=18dB)
Figure 3-1 and Figure 3-2 show the eye diagram of the GS1508 output for two different
output compensation conditions.
Figure 3-2 shows the GS1508 output optimized for wideband return loss of 18dB.
Figure 3-1 shows the GS1508 output optimized for output waveform symmetry. In this
case, the output may not exhibit a return loss of 15dB.
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 varactors (voltage controlled capacitor), as shown in
Figure 3-3.
Consequently, the output capacitance of the GS1508 is dependent on the logic state of
the output.
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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GS1508
SDO
SDO
Figure 3-3: Static Protection Diodes
3.3 Output Return Loss Measurement
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.
A simple method of calculating the values of actual operating return loss is to interpolate
the two return loss measurements. With this method, the values of return loss are
estimated at VCC-0.4V and VCC-1.2V based on the measurements at VCC and VCC-1.6V.
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; the interpolated values are RIH = -17dB and
RIL = -15dB.
3.4 Output Amplitude Adjustment
The output amplitude of the GS1508 can be adjusted by changing the value of the RSET
resistor as shown in Figure 3-4 and Table 3-1. 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.
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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1.000
0.800
0.600
0.400
0.200
0.000
0.0000
0.0050
0.0100
1 / R
0.0150
0.0200
0.0250
(mho)
SET
Figure 3-4: GS1508 Output Amplitude vs. 1/RSET
Table 3-1: RSET vs. VOUT
RSET (Ω)
1/RSET
Output Swing
500.0
150.0
75.0
0.0020
0.0067
0.0133
0.0187
0.0231
0.095
0.298
0.575
0.785
0.937
53.6
43.2
NOTE: For reliable operation of the GS1508 over the full temperature range, do not use
an RSET value below 49.9Ω.
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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4. Input/Output Circuits
V
CC
5k
SDI
SDI
20k
Figure 4-1: SDI/SDI
SDO
SDO
+
-
R
SET
Figure 4-2: SDO/SDO
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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5. Application Information
5.1 Typical Application Circuit
V
CC
C
COMP
COMP
75
100n
75
L
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 and
all capacitors in Farads
unless otherwise shown.
53.6
0µ1
Figure 5-1: GS1508 Typical Application Circuit
Table 5-1: Typical Application Circuit Component Values
Component
Value
53.6
Comments
R
For 800mV output
For 50Ω PCB trace impedance
SET
Z
50Ω
O
L
12nH
Typical value. Component value will vary depending
on PCB layout
COMP
C
0.5pF
Typical value. Component value will vary depending
on PCB layout
COMP
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Data Sheet
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5.2 PCB Layout
Special attention must be paid to component layout when designing serial digital interfaces
for HDTV. Figure 5-3 through Figure 5-6 show the artwork for a four-layer printed circuit
evaluation board for the GS1508. The schematic is shown in Figure 5-2. 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, which are
curved to minimize impedance changes due to change of PCB trace width
5.3 GS1508 Evaluation Board
5.3.1 EB1508 PCB Schematic
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
EDGEMNT_BNC
EDGEMNT_BNC
L3 10n
R10
C13
C12
J6
J5
V
R
GND
EE
V
4µ7
1µ
CC
C15
10n
EDGEMNT_BNC
V
EDGEMNT_BNC
SET CC
75
R11
53.6
C18 0p5
All resistors in Ohms and
all capacitors in Farads
unless otherwise shown.
Figure 5-2: Schematic Diagram for the GS1508 Evaluation Board
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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5.3.2 EB-1508 PCB Layout
Figure 5-4: Ground Layer
Figure 5-3: Top Layer
Figure 5-5: Power Layer
Figure 5-6: Bottom Layer
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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6. Package and Ordering Information
6.1 Package Dimensions
8 SOIC
D
X
Min.
0.054
0.004
0.014
0.189
0.150
0.229
Maꢀ.
A
0.068
0.0098
0.019
0.196
0.157
0.244
A1
B
E
0.010
Gauge Plane
Seating Plane
D
E
q2
Pin 1
L
ID Mark
e
B
DETAIL “A”
H
e
0.050 BSC
DETAIL “A”
0.015 0.004 ꢀ 45°
C
0.0075
0.016
0.0098
0.034
L
C
q1
0.0215 REF
8°
X
q1
q2
A
A1
0°
7° BSC
NOTES:
1. All dimensions in inches unless otherwise stated.
2. Lead coplanarity should be 0 to 0.004” maꢀ.
3. Package surface finishing: VDI 24~27 (dual).
Package surface finishing: VDI 13~15 (16L SOIC[NB] matriꢀ).
4. All dimensions eꢀclude mold flashes.
5. The lead width (B) to be determined at 0.0075”
from the lead tip.
Figure 6-1: Package Dimensions
6.2 Ordering Information
Part Number
Package
Temperature
Pb-free and Green
GS1508-CKAE3
GS1508-CTAE3
8-pin SOIC
0°C to 70°C
0°C to 70°C
Yes
Yes
8-pin SOIC, tape &
reel (250pc)
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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Revision History
Version
ECR
PCN
Date
Changes and/or Modifications
6
154757
—
August 2010
Converted document to new format. Corrected Figure
6-1: Package Dimensions and Ordering Information.
CAUTION
ELECTROSTATIC SENSITIVE DEVICES
DOCUMENT IDENTIFICATION
DATA SHEET
The product is in production. Gennum reserves the right to make changes to
the product at any time without notice to improve reliability, function or
design, in order to provide the best product possible.
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Gennum Corporation assumes no liability for any errors or omissions in this document, or for the use of the circuits or devices described herein. The sale of
the circuit or device described herein does not imply any patent license, and Gennum makes no representation that the circuit or device is free from patent
infringement.
All other trademarks mentioned are the properties of their respective owners.
GENNUM and the Gennum logo are registered trademarks of Gennum Corporation.
© Copyright 1998 Gennum Corporation. All rights reserved.
www.gennum.com
GS1508 HD-LINX™ HDTV Cable Driver
Data Sheet
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