3D7503D-20 Datasheet, PDF (1/5 Pages) Data Delay Devices, Inc. – MONOLITHIC MANCHESTER ENCODER/DECODER

MONOLITHIC MANCHESTER
ENCODER/DECODER
(SERIES 3D7503)
3D7503
data
delay
3
®
devices, inc.
FEATURES
• All-silicon, low-power CMOS technology
• Encoder and decoder function independently
• Encoder has buffered clock output
• TTL/CMOS compatible inputs and outputs
• Vapor phase, IR and wave solderable
• Auto-insertable (DIP pkg.)
• Low ground bounce noise
• Maximum data rate: 50 MBaud
• Data rate range: ±15%
• Lock-in time: 1 bit
PACKAGES
CIN 1 14 VDD
CEN 2 13 CBUF
RX 3 12 LOOP
COUT 4 11 TXENB
DIN 5 10 DOUTB
RESB 6 9 TXB
GND 7 8 TX
3D7503-xxx DIP (.300)
3D7503G-xxx Gull Wing (.300)
3D7503D-xxx SOIC (.150)
FUNCTIONAL DESCRIPTION
PIN DESCRIPTIONS
The 3D7503 is a monolithic CMOS Manchester Encoder/Decoder combo
chip. The device uses bi-phase-level encoding to embed a clock signal
into a data stream for transmission across a communications link. In this
encoding mode, a logic one is represented by a high-to-low transition in
the center of the bit cell, while a logic zero is represented by a low-to-high
transition.
The Manchester encoder combines the clock (CIN) and data (DIN) into a
single bi-phase-level signal (TX). An inverted version of this signal (TXB)
is also available. The data baud rate (in MBaud) is equal to the input
clock frequency (in MHz). A replica of the clock input is also available
(CBUF).
Encoder:
CIN Clock Input
DIN Data Input
RESB Reset
CEN Clock buffer enable
TXENB Transmit enable
CBUF Buffered clock
TX,TXB Transmitted signal
Decoder:
RX
Received Signal
COUT Recovered Clock
DOUTB Recovered Data
The encoder may be reset by setting the RESB input low; otherwise, it
Common:
should be left high. The TX and TXB signals may be disabled (high-Z) by _{LOOP Loop enable}
setting TXENB high. Similarly, CBUF may be disabled by setting CEN
VDD +5 Volts
low. Under most operating conditions, the encoder is never reset, TX and _{GND Ground}
TXB are always enabled, and CBUF is not used. With this in mind, the
3D7503 provides an internal pull-up resistor on RESB and internal pull-
down resistors on CEN and TXENB, so that most users can leave these inputs uncommitted.
The Manchester decoder accepts the embedded-clock signal at the RX input. The recovered clock and
data signals are presented on COUT and DOUTB, respectively, with the data signal inverted. The
operating baud rate (in MBaud) is specified by the dash number of the device. The input baud rate may
vary by as much as ±15% from the nominal device baud rate without compromising the integrity of the
information received.
Because the decoder is not PLL-based, it does not require a long preamble in order to lock onto the
received signal. Rather, the device requires at most one bit cell before the data presented at the output is
valid. This is extremely useful in cases where the information arrives in bursts and the input is otherwise
turned off.
Normally, the encoder and decoder function independently. However, if the LOOP input is set high, the
encoded TX signal is fed back internally into the decoder and the RX input is ignored. This feature is
useful for diagnostics. The LOOP input has an internal pull-down resistor and may be left uncommitted if
this feature is not needed.
©1998 Data Delay Devices
Doc #98009
DATA DELAY DEVICES, INC.
1
12/11/98
3 Mt. Prospect Ave. Clifton, NJ 07013