Pin Designations
Pin
1
Input
Output Enc Dec
Function
Valid word
Comment
A 'high' signals the receipt of a valid word
ꢀ
ꢀ
ꢀ
2
Encoder Shift Clock
Take Data
Shifts data into the encoder on a 'low' to 'high'
transition
ꢀ
3
'high' during data reception after the sync pulse is
identified
ꢀ
ꢀ
ꢀ
4
5
Serial Data Out
Decoder clock
NRZ output of received data
ꢀ
ꢀ
Clock for the transition finder and synchronizer which
generates the clock for the rest of the decoder
ꢀ
ꢀ
ꢀ
ꢀ
6
7
Bipolar Zero In
Should be 'high' when the bus is in a negative state.
Must be tied 'high' when the unipolar input is used
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Bipolar One In
Should be 'high' when the bus is in a positive state.
Must be tied 'low' when the unipolar input is used
8
Unipolar Data In
Decoder Shift Clock
Input for unipolar data to the transition finder. Must be
tied 'low' when not used
9
Provides the DECODER CLOCK divided by 12,
synchronized by the recovered serial data
ꢀ
ꢀ
10
Command/Data Sync This output indicates the type of synchronizing
character received as follows: If a data synchronizing
character was received, this pin is low while the data
is decoded. If a command synchronizing character
was received, this pin is high during data decoding
11
Decoder Reset
A 'high' during a DECODER SHIFT CLOCK rising
edge resets the bit counter
ꢀ
ꢀ
12
13
14
15
VSS
Ground
–
–
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Master Reset
A 'high" clears the counters in both sections
Provides the ENCODER CLOCK divided by 6
ꢀ
¸ 6 Out
ꢀ
ꢀ
Bipolar Zero Out
Provides an active 'low' output to the zero or negative
sense of a bipolar line driver
16
Output Inhibit
A 'low' inhibits the BIPOLAR ZERO OUT and
BIPOLAR ONE OUT by forcing them to inactive, 'high',
states
ꢀ
ꢀ
17
18
19
20
21
Bipolar One Out
Serial Data In
Encoder Enable
Sync Select
Provides an active 'low' output to the one or positive
sense of a bipolar line driver
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Receives serial data at the rate of the ENCODER
SHIFT CLOCK
ꢀ
ꢀ
ꢀ
A 'high' starts the encode cycle provided that the
previous cycle is complete
A 'high' selects the command sync and a 'low' selects
the data sync
Send Data
Provides an active 'high' to enable the external serial
data source
ꢀ
22
23
24
Send Clock In
Encoder Clock
VDD
Clock input at 2 times the data rate
Input to the divide by 6 circuit
Positive Supply
ꢀ
ꢀ
–
ꢀ
ꢀ
ꢀ
–
ꢀ
Figure 4: Pin Designations (24-Pin Dip/FlatPack)
Aeroflex Circuit Technology
SCD15530 REV B 7/28/99 Plainview NY (516) 694-6700
3
AEROFLEX [ AEROFLEX CIRCUIT TECHNOLOGY ]
