
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
DD(+V)
V
SS(-V)
A
B
x4/x1
DNCK
UPCK
PIN A S S IGNMENT - T OP V IEW
CLK
UP/DN
FIGURE 1
1
2
3
4
8
7
6
5
L
RBIAS
V
DD(+V)
V
SS(-V)
A
B
x4/x1
1
2
3
4
8
7
6
5
L
L
L
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