ACT CT1698FP, CT1698 Datasheet

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CT1698

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MIL-STD-1397 Type E 10MHz

Low Level Serial Interface

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

ISO

900

I

1

Serial NRZ Data

10 MHz Shift Clock

20 MHz Gated Clock

Envelope

Master Reset

Encoder Enable

Power Management

Decoded Data Envelope

Clock Regeneration

Clock

R

Serial

Manchester

Encoder

Power

Management

Manchester

Decoder

and

Data

Reconstruction

Drive 1

XFMR SEC/DATA Input

XFMR SEC

Primary

+5V

Primary

XFMR SEC

XFMR SEC/DATA

Drive 2

Rx Strobe

Data

Output

Data

Output

Input

Decoded Data

R

Figure 1 – Block Diagram

eroflex Circuit Technology – Data Bus Modules For The Future © SCDCT1698 REV A 6/12/98

Transmission

Reception

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.

Encoding Timing / Transmitter Specification

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.

Symbol Parameter / Condition Min Typ Max Unit
Encode Timing

t1 Input data set-up time
t2 Encode clock set-up time
t3 Encode envelope set-up time
t4 Encode envelope turn-off time
t5 Transmitter activation set-up time
t6 Transmitter deactivation hold-time
tw1 20 MHz gated CK pulse width high
tw2 Encoder shift CK pulse width high

Output Signals

Va Output amplitude (see Figure 2)
T Pulse period
Ts Width of 1st positive half bit
Te Width of last half bit
T/2 Half pulse period
Tr Pulse rise time
Tf Pulse fall time
Vs Voltage overshoot
Tos Offset Voltage 2T after last zero crossing
Tdtx Delay from 20 MHz clock input to data output on

TXFMR secondary

Zo Output Impedance

10 40 ns
10 40 ns
10 40 ns
10 35 ns

100 ns

50 ns
20 30 ns
45 55 ns

.45 .7 .8 V

97 100 103 ns
45 65 ns
47 65 ns

47 50 53 ns
.05 .3 V/ns
.05 .3 V/ns

100 mV

30 mV

20 55 ns

45 50 55 Ω

Aeroflex Circuit Technology SCDCT1698 REV A 6/12/98 Plainview NY [phone]

2

Aeroflex Circuit Technology SCDCT1698 REV A 6/12/98 Plainview NY [phone]

3

P1 = 50ns ±0.1%
P2 = 100ns ±0.1%

NRZ

BIT NBIT 2BIT 1BIT 0

t

1

Serial Input

t

Encoder

t

2

W2

Shift Clock Input

P2

t

20 MHz

W1

GATED Clock

P1

t

4

NRZ

t

3

Envelope

t

Encoder Enable

5

t

6

Power Management

Pin

T

f

2T

Transmitter

Output

T

dTX

V

a

V

S

V

US

90%

10%

90%

10%

T

T

OS

T/2

T

r

T

Figure 2 Encoder – Transmitter Timing

T

e