CT1698
MIL-STD-1397 Type E 10MHz
Low Level Serial Interface
Features
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•
•
•
•
•
•
•
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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
CIRCUIT TECHNOLOGY
www.aeroflex.com
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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.
Serial NRZ Data
10 MHz Shift Clock
20 MHz Gated Clock
Envelope
Master Reset
Encoder Enable
Power
Management
Power Management
Decoded Data Envelope
Manchester
Decoder
and
Clock Regeneration
Clock
R
Decoded Data
R
Data
Reconstruction
Serial
Manchester
Encoder
Drive 1
XFMR SEC/DATA Input
XFMR SEC
+5V
Primary
Data
Output
Primary
Data
Output
XFMR SEC
XFMR SEC/DATA Input
Drive 2
Rx Strobe
Figure 1 – Block Diagram
eroflex Circuit T
echnology
– Data Bus Modules For The Future © SCDCT1698 REV B 11/6/02
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
Encode Timing
t1
t2
t3
t4
t5
t6
tw
1
tw
2
Output Signals
Va
T
Ts
Te
T/2
Tr
Tf
Vs
Tos
Tdtx
Zo
Aeroflex Circuit Technology
Parameter / Condition
Min
Typ
Max
Unit
Input data set-up time
Encode clock set-up time
Encode envelope set-up time
Encode envelope turn-off time
Transmitter activation set-up time
Transmitter deactivation hold-time
20 MHz gated CK pulse width high
Encoder shift CK pulse width high
10
10
10
10
100
50
20
45
.45
97
45
47
47
.05
.05
50
.7
100
40
40
40
35
ns
ns
ns
ns
ns
ns
30
55
.8
103
65
65
53
.3
.3
100
30
20
55
55
ns
ns
V
ns
ns
ns
ns
V/ns
V/ns
mV
mV
ns
Ω
Output amplitude (see Figure 2)
Pulse period
Width of 1st positive half bit
Width of last half bit
Half pulse period
Pulse rise time
Pulse fall time
Voltage overshoot
Offset Voltage 2T after last zero crossing
Delay from 20 MHz clock input to data output on
TXFMR secondary
Output Impedance
2
45
50
SCDCT1698 REV B 11/6/02 Plainview NY (516) 694-6700
Aeroflex Circuit Technology
BIT 0
NRZ
Serial Input
t
1
BIT 1
BIT 2
BIT N
P1 = 50ns ±0.1%
P2 = 100ns ±0.1%
Encoder
Shift Clock Input
t
2
t
W2
P2
20 MHz
GATED Clock
t
3
NRZ
Envelope
3
t
W1
P1
t
4
t
5
Encoder Enable
Power Management
Pin
T
f
t
6
2T
Transmitter
Output
T
dTX
V
a
V
S
V
US
10%
10%
T
e
T
OS
90%
90%
T
SCDCT1698 REV B 11/6/02 Plainview NY (516) 694-6700
T/2
T
T
r
Figure 2 Encoder – Transmitter Timing
1
st
Data
BIT
Manchester II
Receiver Data
t
1
2
nd
Data
BIT
3
rd
Data
BIT
4
th
Data
BIT
5
th
Data
BIT
Decoded
Data
Envelope
R
X
Data
Data
R
CK
R
t
6
t
5
t
7
t
2
t
3
t
4
t
5
Figure 3 Receiver / Decode Timing
Symbol
Parameter / Condition
Min
Nom
Max
Units
t1
t2
t3
t4
t5
t6
t7
t8
Envelope delay time
Data decode delay
Clock low transition delay
Clock
R
high time
Clock
R
low time
Envelope off delay
Receiver strobe enable to input data set-up time
Receiver strobe disable to input data hold-time
-
-
-
35
35
120
5
20
-
115
130
50
50
-
100
125
-
65
65
270
nsec
nsec
nsec
nsec
nsec
nsec
nsec
?
Power Management Functional Table
Encoder
Enable
(Pin 10)
Power Management
Input
(Pin 9)
Receiver
Status
Transmitter
Status
0
X
1
0
1
X
Active
Active
Active
Standby
Active
Active
Power management timing see Figure 2.
Aeroflex Circuit Technology
4
SCDCT1698 REV B 11/6/02 Plainview NY (516) 694-6700
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:
V
OUT
pk-pk
= 1.39 + 125 ± 15% Volts,
R
EXT
R
EXT
> 90Ω
The formula for peak to peak transmitter output swing with resistors connected between pins 5 and 6 to
ground is:
V
OUT
pk-pk
= 1.39 - 50 (V
EE
-2.5) ± 15% Volts,
R
EXT
R
EXT
> 180Ω
Functional Description and Pinout
Pin
#
Pin Name
Function
Load or
Drive
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
XFMR primary/
TX data output
XFMR secondary
TXDATA output/
RX data input
No connection
Drive 2
Drive 1
-5 Volts
R
X
strobe
Power management
input
Encoder enable
Case/signal GND
Case/signal GND
Decoded data
envelope
TP3 test point
TP1 test point
TP2 test point
-5 Volts
TP4 test point
Clock
R
No connection
Decoded Data
R
Transformer lead for connection to center conductor of tri-axial
cable
Secondary isolated winding, same phase as center conductor
Transmitter-receiver I/O pin (usually connected to pin 2)
Output level adjustment selected by resistor to GND or V
EE
Output level ajustment selected by resistor to GND or V
EE
Low level disables receiver
Controls transmitter power consumption in conjunction with pin 10
Controls transmitter power consumption in conjunction with pin 9
3 S loads
1 S load
1 S load
High after reception of first half bit; goes low after reception of last
half bit (normally low in inactive state)
Alignment point: no electrical connection permitted
Alignment point: no electrical connection permitted
Alignment point: no electrical connection permitted
Alignment point: no electrical connection permitted
Reconstructed clock; one clock pulse per input bit received
NRZ reconstructed data. Sampled on clock
R
rising edge
5
4 S drive
3 S drive
3 S drive
Aeroflex Circuit Technology
SCDCT1698 REV B 11/6/02 Plainview NY (516) 694-6700
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