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
LS7183N
LS7184N
(631) 271-0400 FAX (631) 271-0405
April 2009
PIN ASSIGNMENT - TOP VIEW
A3800
QUADRATURE CLOCK CONVERTER
FEATURES:
• x1, x2 and x4 resolution
• Programmable output pulse width (200ns to 140µs)
• Excellent regulation of output pulse width
• TTL and low voltage CMOS compatible I/Os
• +3V to +12V operation (V
DD
- V
SS
)
•
LS7183N, LS7184N
(DIP);
LS7183N-S, LS7184N-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
LS7183N
and
LS7184N
are CMOS quadrature clock converters.
Quadrature clocks derived from optical or magnetic encoders, when
applied to the A and B inputs of the
LS7183N
/
LS7184N,
are con-
verted to strings of Up Clocks and Down Clocks (LS7183N) or to a
Clock and an Up/Down direction control (LS7184N). These outputs
can be interfaced directly with standard Up/Down counters for direc-
tion and position sensing of the encoder.
INPUT/OUTPUT DESCRIPTION:
RBIAS
(Pin 1)
Input for external component connection. A resistor connected be-
tween this input and V
SS
adjusts the output clock pulse width (Tow).
V
DD
(Pin 2)
Supply Voltage positive terminal.
V
SS
(Pin 3)
Supply Voltage negative terminal.
A, B
(Pin 4, Pin 5)
Quadrature Clock inputs A and B. Directional output pulses are gener-
ated from the A and B clocks according to Fig. 2. A and B inputs have
built-in immunity for noise signals less than 50ns duration (Validation
delay, T
VD
). The A and B inputs are inhibited during the occurrence of
a directional output clock (UPCK or DNCK), so that spurious clocks
resulting from encoder dither are rejected.
MODE
(Pin 6)
MODE is a 3-state input to select resolution x1, x2 or x4. The input
quadrature clock rate is multiplied by factors of 1, 2 and 4 in x1, x2
and x4 mode, respectively, in producing the output UP/DN clocks
(See Fig. 2). x1, x2 and x4 modes selected by the MODE input logic
levels are as follows:
Mode = 0
: x1 selected
Mode = 1
: x2 selected
Mode = Float : x4 selected
8
7
UPCK
DNCK
MODE
B
LSI
LS7183N
6
5
RBIAS
V
DD
(+V )
V
SS
(-V )
A
1
2
3
4
8
7
6
5
FIGURE 1
CLK
UP/DN
MODE
B
LS7183N - DNCK
(Pin 7)
In
LS7183N,
this is the DOWN Clock Output. This output con-
sists of low-going pulses generated when A input lags the B
input.
LS7184N - UP/DN
(Pin 7)
In
LS7184N,
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.
LS7183N - UPCK
(Pin 8)
In
LS7183N,
this is the UP Clock output. This output consists
of low-going pulses generated when A input leads the B in-
put.
LS7184N - CLK
(Pin 8)
In
LS7184N,
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
LS7184N,
the timing of CLK and UP/DN re-
quires that the counter interfacing with
LS7184N
counts on
the rising edge of the CLK pulses.
LSI
LS7184N
7183N/84N-042709-1
FORWARD
A
T
PW
T
PS
T
PS
T
DS
4
1
T
OW
2
2
4
1
4
2
2
4
2
REVERSE
B
UPCLK
(7183N)
DNCLK
(7183N)
CLK
(7184N)
UP/DN
(7184N)
4
4
1
1
4
4
2
2
NOTE:
Output clocks labeled 1, 2 and 4 have the following interpretations.
1: Generated in x1, x2 and x4 modes
2: Generated in x2 and x4 modes only
4: Generated in x4 mode only
FIGURE 2. LS7183N, LS7184N INPUT/OUTPUT TIMING
A
4
FILTER
INHIBIT
LOGIC
DIRECTION
MUX
AND
BUFFER
8
UPCK or CLK
B
5
FILTER
7
1
CURRENT
MIRROR
PULSE
V
DD
1M
DNCK or UP/DN
RBIAS
MODE
6
1M
MODE
DECODE
V
DD
V
SS
2
3
FIGURE 3. LS7183N, LS7184N BLOCK DIAGRAM
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.
7183N/84N-121508-3
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