UL
®
LSI/CSI
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
RBIAS
V
DD
(+V )
V
SS
(-V )
A
1
2
3
4
LS7083N
LS7084N
(631) 271-0400 FAX (631) 271-0405
April 2009
A3800
QUADRATURE CLOCK CONVERTER
FEATURES:
• x1 and x4 mode selection
• Up to 16MHz 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
• +3V to +12V operation (V
DD
- V
SS
)
•
LS7083N, LS7084N
(DIP);
LS7083N-S, LS7084N-S
(SOIC) - See Figure 1
Applications:
• Interface incremental encoders to Up / Down Counters
(See Figure 6A and Figure 6B)
• Interface rotary encoders to Digital Potentiometers
(See Figure 7)
DESCRIPTION:
The
LS7083N
and
LS7084N
are CMOS quadrature clock con-
verters. Quadrature clocks derived from optical or magnetic en-
coders, when applied to the A and B inputs of the
LS7083N
or
LS7084N,
are converted to strings of Up Clocks and Down
Clocks (
LS7083N)
or to a Clock and an Up/Down direction con-
trol (LS7084N). These outputs can be interfaced directly with
standard Up/Down counters for direction and position sensing of
the encoder.
INPUT/OUTPUT DESCRIPTION:
RBIAS
(Pin 1)
Input for external component connection. A resistor connected
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.
Mode
(Pin 6)
Mode is a 3-state input to select resolutions x1, x2 or x4. The se-
lected resolution multiplies the input quadrature clock rate by 1, 2
and 4, respectively, in producing the outputs UPCK / DNCK and
CLK (see Figure 2).
The Mode input logic levels selects resolutions as follows:
Logic 0 = x1 Float = x2 Logic 1 = x4
PIN ASSIGNMENT - TOP VIEW
LSI
LS7083N
LSI
8
7
6
5
UPCK
DNCK
MODE
B
RBIAS
V
DD
(+V )
V
SS
(-V )
A
1
2
3
4
8
7
6
5
CLK
UP/DN
MODE
B
FIGURE 1
LS7083N - DNCK
(Pin 7)
In
LS7083N,
this is the DOWN Clock Output. This output consists of
low-going pulses generated when A input lags the B input.
LS7084N - UP/DN
(Pin 7)
In
LS7084N,
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.
LS7083N - UPCK
(Pin 8)
In
LS7083N,
this is the UP Clock output. This output consists of
low-going pulses generated when A input leads the B input.
LS7084N - CLK
(Pin 8)
In
LS7084N,
this is the combined UP Clock and DOWN Clock out-
put. The count direction at any instant is indicated by the UP/DN
output (Pin 7).
NOTE:
For the
LS7084N,
the timing of CLK and UP/DN requires
that the counter interfacing with
LS7084N
counts on the rising edge
of the CLK pulses.
LS7084N
7083N/84N-042109-1
LSI [ LSI COMPUTER SYSTEMS ]
