QUADRATURE CLOCK CONVERTER
FEATURES:
x1 and x4 mode selection
Up to 16 MHz output clock frequency
Programmable output clock pulse width
On-chip filtering of inputs for optical or
magnetic encoder applications.
TTL and CMOS compatible I/Os
+4.5V to +10.0V operation (V
DD
-V
SS
)
LS7083, LS7084 (DIP)
LS7083-S, LS7084-S (SOIC) - See Figure 1
INPUT/OUTPUT DESCRIPTION:
RBIAS (Pin 1)
Input for external component connection. A resistor con-
nected between this input and V
SS
adjusts the output clock
pulse width (Tow). For proper operation, the output clock
pulse width must be less than or equal to the A,B pulse
separation (T
OW
T
PS)
.
V
DD
(Pin 2)
Supply Voltage positive terminal.
V
SS
(Pin 3
)
Supply Voltage negative terminal.
A (Pin 4)
Quadrature Clock Input A. This input has a filter circuit to
validate input logic level and eliminate encoder dither.
B (Pin 5)
Quadrature Clock Input B. This input has a filter circuit
identical to input A.
x4/x1 (Pin 6)
This input selects between x1 and x4 modes of operation.
A high-level selects x4 mode and a low-level selects the x1
mode. In x4 mode, an output pulse is generated for every
transition at either A or B input. In x1 mode, an output
pulse is generated in one combined A/B input cycle.
(See Figure 2.)
LS7083 - DNCK (Pin 7)
In LS7083, this is the DOWN Clock Output. This output con-
sists of low-going pulses generated when A input lags the B
input.
LS7084 - UP/DN (Pin 7)
In LS7084, this is the count direction indication output.
When A input leads the B input, the UP/DN output goes high
indicating that the count direction is UP. When A input lags
the B input, UP/DN output goes low, indicating that the count
direction is DOWN.
LS7083 - UPCK (Pin 8)
In LS7083, this is the UP Clock output. This output consists
of low-going pulses generated when A input leads the B in-
put.
LS7084 - CLK (Pin 8)
In LS7084, this is the combined UP Clock and DOWN Clock
output. The count direction at any instant is indicated by the
UP/DN output (Pin 7).
NOTE: For the LS7084, the timing of CLK and UP/DN re-
quires that the counter interfacing with LS7084 counts on the
rising edge of the CLK pulses.
DESCRIPTION:
The LS7083 and LS7084 are monolithic CMOS silicon gate
quadrature clock converters. Quadrature clocks derived
from optical or magnetic encoders, when applied to the A
and B inputs of the LS7083/LS7084, are converted to strings
of Up Clocks and Down Clocks (LS7083) or to a Clock and
an Up/Down direction control (LS7084). These outputs can
be interfaced directly with standard Up/Down counters for di-
rection and position sensing of the encoder.
October 2000
RBIAS
V
D D ( + V )
V
S S ( - V )
A
B
x4/x1
D N C K
UPCK
PIN ASSIGNMENT - TOP VIEW
CLK
U P / D N
FIGURE 1
1
2
3
4
8
7
6
5
LS7084
RBIAS
V
D D ( + V )
V
S S ( - V )
A
B
x4/x1
1
2
3
4
8
7
6
5
LS7083
LSI
LSI
7083/84-100600-1
LSI/CSI
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405
LS7083/7084
UL
A3800
ABSOLUTE MAXIMUM RATINGS
:
PARAMETER
SYMBOL
VALUE
UNITS
DC Supply Voltage
V
DD
- V
SS
11.0
V
Voltage at any input
V
IN
V
SS
-.3 to V
DD
+.3
V
Operating temperature T
A
0 to +70 C
Storage temperature T
STG
-55 to +150 C
DC ELECTRICAL CHARACTERISTICS:
(All voltages referenced to V
SS
, T
A
= 0C to 70C.)
PARAMETER
SYMBOL
MIN MAX
UNITS
CONDITION
Supply voltage
V
DD
4.5
10.0
V
-
Supply current
I
DD
-
6.0
A
V
DD
= 10.0V, All
input frequencies = 0 Hz
RBIAS = 2M
x4/x1 Logic Low
V
IL
0.3V
DD
-
V
A,B Logic Low
V
IL
-
0.6
V
V
DD
= 4.5V
-
1.0
V
V
DD
= 9V
-
1.1
V
V
DD
= 10.0V
x4/x1Logic High
V
IH
0.7V
DD
-
V
-
A,B Logic High
V
IH
3.1
-
V
V
DD
= 4.5V
5.0
-
V
V
DD
= 9V
5.6
-
V
V
DD
= 10.0V
ALL OUTPUTS:
Sink Current
I
OL
1.75
-
mA
V
DD
= 4.5V
V
OL
= 0.4V
5.0
-
mA
V
DD
= 9V
5.7
-
mA
V
DD
= 10.0V
Source Current
I
OH
1.0
-
mA
V
DD
= 4.5V
V
OH
= V
DD
- 0.5V
2.5
-
mA
V
DD
= 9V
3.0
-
mA
V
DD
= 10.0V
TRANSIENT CHARACTERISTICS:
(T
A
= 0C to 70C)
PARAMETER
SYMBOL
MIN
MAX
UNITS
CONDITION
A,B inputs:
Validation Delay
Tv
D
-
85
ns
V
DD
= 10.0V
-
100
ns
V
DD
= 9V
-
160
ns
V
DD
= 4.5V
A,B inputs:
Pulse Width
T
PW
T
VD
+T
OW
Infinite
ns
-
A to B or B to A
Phase Delay
T
PS
T
OW
Infinite
ns
-
1
A,B frequency
f
A,B
-
2T
PW
Hz
-
Input to Output Delay
T
DS
-
120
ns
V
DD
= 10.0V
-
150
ns
V
DD
= 9V
-
235
ns
V
DD
= 4.5V
Includes input
validation delay
Output Clock Pulse Width
T
OW
50
-
ns
See Fig. 4 & 5
7083/84-100100-2
B
UPCK
( x 1 / 7 0 8 3 )
DNCK
( x 1 / 7 0 8 3 )
UPCK
( x 4 / 7 0 8 3 )
CLK
( x 1 / 7 0 8 4 )
DNCK
( x 4 / 7 0 8 3 )
CLK
( x 4 / 7 0 8 4 )
U P / D N
( 7 0 8 4 )
T
DS
T
DS
T
OW
T
PS
T
PW
A
FIGURE 2. LS7083/LS7084 INPUT/OUTPUT TIMING DIAGRAM
CLOCK
AND
DIRECTION
DECODE
DUAL
ONE-SHOT
DUAL
ONE-SHOT
CURRENT
MIRROR
FILTER
FILTER
A
B
x 4 / x 1
V
DD
V
SS
MUX
x4 CLOCK
x1 CLOCK
UP/DN
8
7
UPCK or CLK
DNCK or UP/DN
1
4
5
6
2
3
FIGURE 3. LS7083/LS7084 BLOCK DIAGRAM
RBIAS
+V
-V
7083/84-100100-3
The information included herein is believed to be
accurate and reliable. However, LSI Computer Systems,
Inc. assumes no responsibilities for inaccuracies, nor for
any infringements of patent rights of others which may
result from its use.
Figure 4. Tow vs RBIAS, K
V
DD
=5V
V
DD
=9V
V
DD
=10.0V
100
200
300
400
500
250
500
750
1000
1250
1500
OUTPUT CLOCK PULSE WIDTH, Tow, ns
V
DD
=5V
V
DD
=9V
V
DD
=10.0V
25
30
20
15
10
5
2
4
6
8
10
12
Figure 5. Tow vs RBIAS, M
OUTPUT CLOCK PULSE WIDTH, Tow, s
7083/84-100100-4
ENCODER
A CLOCK
B CLOCK
6
2
8
7
4
5
8
16
V
DD
CK-UP
CK-DN
4 0 1 9 3
3
A
B
R
B
4
5
1
+V
V
SS
L S 7 0 8 3
x4/x1
V
DD
UPCK
DNCK
FIGURE 6A. TYPICAL APPLICATION FOR LS7083 IN x4 MODE
+V
RBIAS
V
SS
ENCODER
A CLOCK
B CLOCK
6
2
8
7
8
16
V
DD
3
A
B
4
5
1
+V
x4/x1
V
DD
+V
CK
U P / D N
V
SS
15
10
L S 7 0 8 4
RBIAS
4 5 1 6
CLK
U P / D N
MODE SELECT
FIGURE 6B. TYPICAL APPLICATION FOR LS7084 WITH x4/x1 MODE SELECTION
R
R
B
V
SS
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