eroflex Circuit T
echnology
Data Bus Modules For The Future SCDCT1815 REV A 6/12/98
Features
Internally set threshold
Matched to 50 ohm system impedance power on and off
Operates with 5 volt supplies
Power management
Accepts synchronous input data
Unique Manchester decoder requires no clock
Generates one clock per received bit
May be used for serial decoding of indefinite word lengths
Other Wire and Fiber Optic types available
General Description
The CT1815 is a single hybrid micro-circuit which incorporates a serial encoder, transceiver, and Manchester decoder
in one package. The encoder accepts serial NRZ data in conjunction with two synchronous clocks. This data stream is
then Manchester encoded and maybe transformer coupled thru an external transformer to a 75 ohm tri-axial cable for
transmission through up to 1000 feet of cable. The CT1815 receiver section accepts bipolar Manchester encoded
signals and passes level detected signals to the serial decoder. The serial decoder reconstructs an NRZ data stream
with derived clock. This allows the data to be processed by our CT2500 monolithic protocol chip for MIL-STD-1397 serial
interfaces. All the input and output signals of the CT1815 are completely compatible with the CT2500. The CT1815 has
a power management function. A transmitter standby mode is available to reduce the overall power consumption of the
CT1815. Aeroflex Circuit Technology is an 80,000ft
2
MIL-PRF-38534 certified facility in Plainview, N.Y.
CIRCUIT TECHNOLOGY
www.aeroflex.com
for MIL-STD-1397 Type D
10MHz Low Level Serial Interface
F
I
E
I
D
C
E
R T
A
E
R
O
F
L E
X L A
B
S
I
N
C
.
ISO
9001
Serial
Manchester
Encoder
Power
Management
Manchester
Decoder
and
Clock Regeneration
Data
Reconstruction
Serial NRZ Data
10 MHz Shift Clock
20 MHz Gated Clock
Envelope
Master Reset
Encoder Enable
Power Management
Decoded Data Envelope
Clock
R
Decoded Data
R
Rx Strobe
XFMR SEC/DATA Input
Primary
Output
+5V
XFMR SEC/DATA Input
Data
Primary
Output
Data
XFMR
SEC
XFMR SEC
Figure 1 Block Diagram
External to
Hybrid
1CT:1
ACT15-1031
CT1815
78
Aeroflex Circuit Technology
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
2
Transmission
The CT1815 accepts synchronous NRZ Data in
conjunction with two clocks signals. The NRZ data
stream is then converted to Manchester code which
is transformer coupled to a 75 ohm Tri-axial cable for
transmission up to 1000 ft.
The transmitter may be placed into standby
condition. This reduces power consumption by
approximately 600mW. Power management is made
available via two standard TTL input pins. The
Receiver is always active and is not affected by the
power management circuitry.
The transceiver is matched for 75 ohm operation
over a wide band of frequencies. This condition is
maintained with power on and off.
Reception
The CT1815 receiver section accepts a bipolar
signal which is level detected and passed to the
serial decoder. The decoder section reconstructs
the data and strips the clock from the serial stream.
An NRZ decoded data stream is then produced
synchronously with a recovered clock. The receiver
is designed to meet the MIL-STD-1397 Type D
requirements.
Electrical Requirements
The specification detailed herein encompasses a
hybrid Transceiver/Encoder-Decoder designed to
meet the requirements of the MIL-STD-1397 Type D.
The transceiver is transformer coupled to the
specified triaxial cable and is screened to the
individual test methods of MIL-STD-883
See Figure 1 for Block Diagram. Inputs and
Outputs are all Synchronous NRZ DATA STREAMS
Transformer Isolation
The CT1815 is connected with pin 3 and pin 32 to
the ACT15-1031 transformer secondary winding.
The center tap of the secondary winding is
connected to +5 volts. For matching 75
load
operation, a 78
resistor must be placed across the
primary winding of the transformer.
Encoder Timing / Transmitter Specification
Symbol
Parameter / Condition
Min
Typ
Max
Unit
Encode Timing
t1
Input data set-up time
10
40
ns
t2
Encode clock set-up time
10
40
ns
t3
Encode envelope set-up time
10
40
ns
t4
Encode envelope turn-off time
10
35
ns
t5
Transmitter activation set-up time
150
ns
t6
Transmitter deactivation hold-time
50
ns
tw1
20 MHz gated CK pulse width high
20
30
ns
tw2
Encoder shift CK pulse width high
45
55
ns
Output Signals
Va
Output amplitude (see Figure 2)
2.75
3.25
3.75
V
T
Pulse period
97
100
103
ns
Ts
Width of 1st positive half bit
45
65
ns
Te
Width of last half bit
47
65
ns
T/2
Half pulse period
47
50
53
ns
Tr
Pulse rise time
2.0
V/ns
Tf
Pulse fall time
2.0
V/ns
Vs
Voltage overshoot
350
mV
Tos
Offset Voltage 2T after last zero crossing
150
mV
Tdtx
Delay from 20 MHz clock input to data output on
transformer secondary
20
55
ns
Zo
Output Impedance
70
75
80
A
e
r
o
f
l
e
x
C
i
r
c
u
i
t
T
e
c
h
n
o
l
o
g
y
S
C
D
C
T
1
8
1
5
R
E
V
A
6
/
1
2
/
9
8
P
l
a
i
n
v
i
e
w
N
Y
(
5
1
6
)
6
9
4
-
6
7
0
0
3
BIT N
BIT 2
BIT 1
BIT 0
t
1
t
2
t
W2
t
3
t
5
T
f
P1
P2
t
W1
t
4
t
6
V
a
V
S
V
US
T
dTX
T
r
T/2
T
T
e
2T
T
T
OS
90%
10%
90%
10%
NRZ
Serial Input
Encoder
Shift Clock Input
20 MHz
GATED Clock
NRZ
Envelope
Encoder Enable
Power Management
Pin
Transmitter
Output
P1 = 50ns 0.1%
P2 = 100ns 0.1%
Figure 2 Encoder Transmitter Timing
Aeroflex Circuit Technology
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
4
t
1
t
7
t
2
t
3
t
4
t
5
t
5
t
6
5
th
Data
BIT
4
th
Data
BIT
3
rd
Data
BIT
2
nd
Data
BIT
1
st
Data
BIT
Manchester II
Receiver Data
Decoded
Data
Envelope
R
X
Data
Data
R
CK
R
Figure 3 Receiver / Decode Timing
Symbol
Parameter / Condition
Min
Nom
Max
Units
t1
Envelope delay time
-
45
100
nsec
t2
Data decode delay
-
115
125
nsec
t3
Clock low transition delay
-
130
-
nsec
t4
Clock
R
high time
35
50
65
nsec
t5
Clock
R
low time
35
50
65
nsec
t6
Envelope off delay
120
-
270
nsec
t7
Receiver strobe enable to input data set-up time
5
-
-
nsec
t8
Receiver strobe disable to input data hold-time
20
-
-
?
Power Management Functional Table
Encoder
Enable
(Pin 10)
Power Management
Input
(Pin 9)
Receiver
Status
Transmitter
Status
0
0
Active
Standby
X
1
Active
Active
1
X
Active
Active
Power management timing see Figure 2.
Aeroflex Circuit Technology
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
5
Functional Description and Pinout
Pin
#
Pin Name
Function
Load or
Drive
1
No connection
2
No connection
3
XFMR secondary/
RX data input
Transmitter-receiver I/O pin
4
Test Point
No connection permitted
5
Test Point
No connection permitted
6
Test Point
No connection permitted
7
-5 Volts
8
R
X
strobe
Low level disables receiver
3 S loads
9
Power management
input
Controls transmitter power consumption in conjunction with pin 10
1 S load
10
Encoder enable
Controls transmitter power consumption in conjunction with pin 9
1 S load
11
Case/signal GND
12
Case/signal GND
13
Decoded data
envelope
High after reception of first half bit; goes low after reception of last
half bit (normally low in inactive state)
4 S drive
14
TP3 test point
Alignment point: no electrical connection permitted
15
TP1 test point
Alignment point: no electrical connection permitted
16
TP2 test point
Alignment point: no electrical connection permitted
17
-5 Volts
18
TP4 test point
Alignment point: no electrical connection permitted
19
Clock
R
Reconstructed clock; one clock pulse per input bit received
3 S drive
20
No connection
21
Decoded Data
R
NRZ reconstructed data. Sampled on clock
R
rising edge
3 S drive
22
No connection
23
+5 volts
24
+5 volts
25
10 MHz encoder shift
clock
One cycle required per data bit. Must be high in first half of bit cell
1 S load
26
NRZ serial input data
Serial input to be Manchester encoded with the 20 MHz gated CK
1 S load
27
Encode envelope
Must be high to enable transmission; must go low before reception
of last 20 MHz positive edge to complete transmission
1 S load
28
20 MHz gated clock
(encoder)
Each bit to be encoded requires two positive edges of the 20 MHz
CK. These edges must occur at 25ns and 75ns into the bit cell.
The end of transmission requires an additional edge in conjunction
with a logic low on the encode envelope. t
R
, t
F
< 5nsec.
1 S load
29
Master reset
reset pulse <15 nsec
Logic low resets encoder
2 S load
30
No connection
31
No connection
32
XFMR secondary/
RX DATA input
Transmitter-Receiver I/O pin
33
XFMR secondary
Secondary isolated winding, same phase as outer conducter
34
XFMR primary/
TX DATA output
Transformer lead for connection to outer conductor of tri-axial
Aeroflex Circuit Technology
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
6
Load and Drive Definitions
1 S load: requires
I
IL
= -2mA max., V
IL
= 0.8V max
I
IH
= 50A max., V
IH
= 2.5V min C
IN
< 15 pf
1 S drive:
I
OH
= 50A min., V
OH
= 2.5V min
I
OL
= -2 mA min., V
OL
= 0.5V max
Absolute Maximum Ratings
V
CC
(Pins 23, 24) +7 Volts Max
V
EE
(Pins 7, 17)
-7 Volts Max
Logic Input Voltage Applied:
Logic Low
-1.2V @ 10mA Max
Logic High
+5.5 Volts
Damage will not result from cable open circuits or
short circuits (on the transformer primary) of the
following types:
Line-to-line
Line-to-ground
120V AC 60Hz common mode signal
Environmental Parameters
Operating Temperature
-55C to +100C Case
Storage Temperature
-55C to +150C
Screened per individual test methods of
MIL-STD-883.
Power Consumption
Current (mA)
Typ
Max
I
CC
Standby mode
235
305
I
EE
Standby mode
75
100
I
CC
100% Transmission
447
585
I
EE
100% Transmission
242
315
Aeroflex Circuit Technology
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
7
C I R C U I T T E C H N O L O G Y
Aeroflex Circuit Technology
35 South Service Road
Plainview New York 11830
Telephone: (516) 694-6700
FAX: (516) 694-6715
Toll Free Inquiries: 1-(800)THE-1553
Ordering Information
Model Number
Package
CT1815
Plug-in Package
CT1815FP
Flat Package
Pin 1 & ESD
Designator
1.810
MAX
.100 TYP
Both Sides
1.200 .005
.100 .005
TYP
.018 .002
DIA
(17 Pins/Side)
.120 .010
Both Sides
.200
.270 .010
1.410
MAX
.015 .003
.100 .005
Lead 1 & ESD
Designator
1.810
MAX
.400 MIN
.180 MAX
.010 .002
Plug-In Package Outline
Flat Package Outline
Specifications subject to change without notice.
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