EL4543 Datasheet, PDF (14/16 Pages) Intersil Corporation – Triple Differential Twisted-Pair Driver with Common-Mode Sync Encoding

EL4543
EL4543/EL5375/EL8201 CAT-5 RGB +
Sync Video Transmission System
Introducing a low cost turn-key system for transmitting
component video over short to moderate CAT-5 cable
lengths (1 to 500 feet) with selectable cable loss and skew
compensation. Using only 3 of the 4 pairs in standard CAT-5
the 4^th pair is available for audio, function control or data
transmission; an additional benefit.
RGB video plus sync (5 channels) is received at the VGA
terminal and presented single ended to the EL4543. The
EL4543 converts single ended RGB into fully differential
signals on three twisted pairs. Sync is encoded on the three
RGB differential signals as differential common mode and
then drives the differential signals with encoded sync
through CAT-5 cable. The common mode of the signals is
extracted from the differential signals with a passive network
of resistors and passed to the EL8201 for sync decoding.
The differential signal is passed directly to the EL5375 where
it is amplified, converted back into single ended format.
Signal attenuation occurs in all transmission lines as a
function of increasing cable length; this application system
utilizes individual channel 2-pole compensation for cable
lengths of 150, 300 and 500 feet. Additionally, the
compensation network can be manipulated to provide some
measure of cable prop delay skew compensation for slight
differences in cable lengths between CAT-5 pairs. Cable
skew can best be done around the 300 ft range by under
compensating the shortest color pair (color on the left side of
a vertical line) and over compensate the longest color pair
(color on the right side of a vertical line). Around 450 ft only
the shortest color pair can be under compensated.
The board for the driver and receiver should use strip lines
or strip line waveguides for the inputs and outputs of the
drivers and receivers. The 75Ω input and output strip lines
waveguide on 0.06 inch epoxy board with ground back plain
should be 0.016 inch wide with 0.01 inch space to ground
area around them. The diff pair strip line waveguides should
be two 0.045 inch 50Ω lines spaced 0.01 inch apart and
spaced 0.01 inch to ground area around them. This is a
general guide and size values may very for many reasons.
The receiver feedback and gain resistor network which goes
directly to the minus input should be connected very close
with minimal trace length and minimal capacitance to
ground. The ground plane on the backside of the board, in
back of these resistors and the minus input pin should be
removed as well.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
INPUT
Red In
Green In
Blue In
1 _EN EL4543 QSOP
R1
75
2 _INA+
3 _INA-
4 _N.C.
R2 1K
R3 1K
5 _VSYNC
6 _HSYNC
7 _N.C.
R4 75
8 _INB+
9 _INB-
10 _N.C.
11 _INC+
R5 75
12 _INC-
OUTA+
OUTA-
N.C.
VS+
VS-
R6
24
49.9
Red Out Differential
23
R7
22
49.9
Input +5V
21
C1
20
0.1uf
N.C. ¹⁹
R8
OUTB+
18
49.9
Green Out Differential
OUTB- ¹⁷
R9
N.C. ¹⁶
49.9
R10
OUTC+ ¹⁵
49.9
Blue Out Differential
OUTC- ¹⁴
R11
N.C. ¹³
49.9
EL4543IU
Input +5V
JB1
+VS In
+
Csup1
JB3 4.7uF
GND
JP+
JUMPER
JB2
-VS In
JB4
+VS Out
JB6
GND
Output +5V
+ Csup3
4.7uF
JB5
-VS Out
Input -5V
Csup2
4.7uF
JP-
JUMPER
Output -5V
Csup4
4.7uF
OUTPUT
R12
R13
57
57
R14
49.9
C2
R21
0.1uF 1K
R15
R16
57
57
R17
49.9
C3 R22
0.1uF 1K
R18
R19
55
55
R20
49.9
C4
R23
0.1uF 1K
Output +5V
R35
0
R34
Open
1
U2
REF1
2 _INP1
Output +5V
R37
0
R36
Open
3 _INN1
4 _NC
5 _REF2
6 _INP2
7
Output +5V
R38
8
Open
R39
9
0
10
INN2
NC
REF3
INP3
11
INN3
12
NC
NC
FB1
OUT1
NC
VSP
VSN
NC
FB2
OUT2
EN
FB3
OUT3
EL5375
24
R40
2K
23
22
R41
C20
2K
~4pF
R47
500
21
Output +5V
C5
20
0.1uF
C6
19
0.1uF
R48
1K
150 Feet Comp
R53 10K
C7 C8
36p 10p
R54
68K
18Output -5V
17
16
15
14
13
R43
2K
C21
~4pF
R45
2K
R44 R49 R50
2K
500 1K
R51
R52
1K
500
C22
R46
~4pF
2K
Compensation Control Switch
On
Off
1
12
2
11
3
10
4
9
5
8
6
7
SW DIP-6
300 Feet Comp
R61 3.9K
C15 C16
68p 22p
R62
33K
C4a
220pF
1
2
_
3
4 _VS-
EL8201IS
VS+ ⁸
C19
0.1uF
Output +5V
7
_
6
5
U3
300 Feet Comp
R55 3.9K
C9
68p C10
22p
R56
33K
150 Feet Comp
R57 10K
R58
C11
C12 68K
36p
10p
300 Feet Comp
R59 3.9K
C13
C14 R60
68p
22p 33K
150 Feet Comp
R63 10K
R64
C17
C18 68K
36p
10p
R64 75
R63 75
1
2
3
R65 75
4
5
6
7
8
9
10
11
R66 75
12
13
14
R67 75
15
OUTPUT
Ground
JUMPER
INPUT
14
FN7325.5
October 26, 2005