eroflex Circuit Technology – 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
900
1
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
ClockR
Decoded DataR
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
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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
tw120 MHz gated CK pulse width high 20 30 ns
tw2Encoder shift CK pulse width high 45 55 ns
Output Signals
Va Output amplitude (see Figure 2) .45 .7 .8 V
TPulse period 97 100 103 ns
Ts Width of 1st positive half bit 45 65 ns
TeWidth of last half bit 47 65 ns
T/2 Half pulse period 47 50 53 ns
TrPulse 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 Ω
Aeroflex Circuit Technology SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
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BIT NBIT 2BIT 1BIT 0
t1
t2tW2
t3
t5
Tf
P1
P2 tW1
t4
t6
VaVSVUS
TdTX
Tr
T/2
T
Te
2T
T
TOS
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
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t1
t7t2
t3t4
t5
t5
t6
5th Data
BIT
4th Data
BIT
3rd Data
BIT
2nd Data
BIT
1st Data
BIT
Manchester II
Receiver Data
Decoded
Data
Envelope
RXData
DataR
CKR
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 ClockR high time 35 50 65 nsec
t5 ClockR low time 35 50 65 nsec
t6 Envelope off delay 120 -270 nsec
t7 Receiver strobe enable to input data set-up time 5nsec
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
X1Active Active
1XActive Active
Power management timing see Figure 2.
Aeroflex Circuit Technology SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
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Drive Level Control Pins
External Resistors may be connected from pins 5 and 6 to VEE 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 VEE 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 VEE
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
1XFMR primary/
TX data output Transformer lead for connection to center conductor of tri-axial
cable
2XFMR secondary Secondary isolated winding, same phase as center conductor
3TXDATA output/
RX data input Transmitter-receiver I/O pin (usually connected to pin 2)
4No connection
5Drive 2 Output level adjustment selected by resistor to GND or VEE
6Drive 1 Output level ajustment selected by resistor to GND or VEE
7-5 Volts
8RX strobe Low level disables receiver 3 S loads
9Power 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 ClockRReconstructed clock; one clock pulse per input bit received 3 S drive
20 No connection
21 Decoded DataRNRZ reconstructed data. Sampled on clockR rising edge 3 S drive
VOUT = 1.39 + 125 ± 15% Volts, REXT > 90Ω
REXT
pk-pk
VOUT = 1.39 - 50 (VEE -2.5) ± 15% Volts, REXT > 180Ω
pk-pk REXT
Aeroflex Circuit Technology SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
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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. tR, tF < 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
IIL = -2mA max., VIL = 0.8V max
IIH = 50µA max., VIH = 2.5V min CIN < 15 pf
1 S drive:
IOH = 50µA min., VOH = 2.5V min
IOL = -2 mA min., VOL = 0.5V max
Absolute Maximum Ratings
VCC (Pins 23, 24) +7 Volts Max
VEE (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 -55°C to +100°C Case
Storage Temperature -55°C to +150°C
Screened per individual test methods of
MIL-STD-883
Power Consumption
Current (mA)
Typ Max
ICC Standby mode 325 450
IEE Standby mode 85 105
ICC 100% Transmission 380 510
IEE 100% Transmission 125 160
Aeroflex Circuit Technology SCDCT1698 REV A 6/12/98 Plainview NY (516) 694-6700
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CIRCUIT TECHNOLOGY
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.
