eroflex Circuit T
echnology
Data Bus Modules For The Future SCDCT1698 REV A 6/12/98
Features
Optional transformer isolation
Internally set threshold
Matched to 50 ohm system impedance power on and off
Operates with 5 volt supplies
Power management
External output level adjustment
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
Interfaces directly to the CT2500 protocol device
Other Wire and Fiber Optic types available
General Description
CT1698 is a single hybrid microcircuit which incorporates a serial encoder, transceiver, and Manchester decoder in one package.
The encoder accepts serial NRZ data in conjunction with two synchronous clocks. The CT1698 receiver section accepts bipolar
Manchester encoded signals and passes level detected signals to the serial decoder. The CT1698 has a power management function
and a variable drive level option. The transmitter standby mode is available to reduce the overall power consumption of the CT1698.
The variable drive level output is externally programmable for testing purposes. Aeroflex Circuit Technology is a 80,000 square foot
MIL-PRF-38534 certified facility in Plainview, N.Y.
CIRCUIT TECHNOLOGY
www.aeroflex.com
Low Level Serial Interface
CT1698
MIL-STD-1397 Type E 10MHz
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
Drive 2
Drive 1
Data
Primary
Output
Data
XFMR SEC
XFMR SEC
Figure 1 Block Diagram
Aeroflex Circuit Technology
SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
2
Transmission
The CT1698 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 50 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 drive level of the transmitter may be changed
by adding external resistors to the drive pins. These
pins allow the designer to externally program the
transmitter output level from 0.7 to 2.8 Volts peak to
peak.
The transceiver is matched for 50 ohm operation
over a wide band of frequencies. This condition is
maintained with power on and off.
Reception
The CT1698 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 E
requirements.
Electrical Requirements
The specification detailed herein encompasses a
hybrid Transceiver/Encoder-Decoder designed to
meet the requirements of the MIL-STD-1397 Type E.
The transceiver is transformer coupled to the
specified triaxial cable.
See Figure 1 for Block Diagram. Inputs and
Outputs are all Synchronous NRZ DATA STREAMS.
The transformer is internal to the package with its
use being optional.
Encoding 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
100
ns
t6
Transmitter deactivation hold-time
50
ns
tw
1
20 MHz gated CK pulse width high
20
30
ns
tw
2
Encoder shift CK pulse width high
45
55
ns
Output Signals
Va
Output amplitude (see Figure 2)
.45
.7
.8
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
.05
.3
V/ns
Tf
Pulse fall time
.05
.3
V/ns
Vs
Voltage overshoot
100
mV
Tos
Offset Voltage 2T after last zero crossing
30
mV
Tdtx
Delay from 20 MHz clock input to data output on
TXFMR secondary
20
55
ns
Zo
Output Impedance
45
50
55
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
6
9
8
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
SCDCT1698 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
-
-
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
SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
5
Drive Level Control Pins
External Resistors may be connected from pins 5 and 6 to V
EE
or GND to change the Transmitter Output
Level. If pins 5 and 6 are left open the CT1698 operates within the MIL-STD-1397 Type E specification.
Resistors connected from pins 5 and 6 to V
EE
or Ground must be equal. Unequal resistors will result in a
transmitter output offset level.
The formula for peak to peak transmitter output swing with resistors connected between 5 and 6 to V
EE
is:
The formula for peak to peak transmitter output swing with resistors connected between pins 5 and 6 to
ground is:
Functional Description and Pinout
Pin
#
Pin Name
Function
Load or
Drive
1
XFMR primary/
TX data output
Transformer lead for connection to center conductor of tri-axial
cable
2
XFMR secondary
Secondary isolated winding, same phase as center conductor
3
TXDATA output/
RX data input
Transmitter-receiver I/O pin (usually connected to pin 2)
4
No connection
5
Drive 2
Output level adjustment selected by resistor to GND or V
EE
6
Drive 1
Output level ajustment selected by resistor to GND or V
EE
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
V
OUT
= 1.39 + 125 15% Volts, R
EXT
> 90
R
EXT
pk-pk
V
OUT
= 1.39 - 50 (V
EE
-2.5) 15% Volts, R
EXT
> 180
pk-pk
R
EXT
Aeroflex Circuit Technology
SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
6
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
TXDATA output/
RX DATA input
Transmitter-Receiver I/O pin (usually connected to pin 33)
33
XFMR secondary
Secondary isolated winding, same phase as outer signal
conductor
34
XFMR primary/
TX DATA output
Transformer lead for connection to outer signal conductor of
tri-axial
Functional Description and Pinout (continued)
Pin
#
Pin Name
Function
Load or
Drive
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
When used with the internal transformer, the
CT1698 will not be damaged by cable open circuits
or by short circuits of the following types:
Line-to-line
Line-to-ground
To voltage sources of 0 to 115 volts
alternating current, 60 hertz, line-to-ground
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
325
450
I
EE
Standby mode
85
105
I
CC
100% Transmission
380
510
I
EE
100% Transmission
125
160
Aeroflex Circuit Technology
SCDCT1698 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
CT1698
Plug-in Package
CT1698FP
Flat Package
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
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
Specifications subject to change without notice.
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