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

• LS7183, LS7184 (DIP);

LS7183-S, LS7184-S (SOIC) - See Figure 1

INPUT/OUTPUT DESCRIPTION:

RBIAS (Pin 1)

Input for external component connection. A resistor connected be-

Supply Voltage positive terminal.

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

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

LS7183 - DNCK (Pin 7)

In LS7183, this is the DOWN Clock Output. This output con-

sists of low-going pulses generated when A input lags the B

input.

LS7184 - UP/DN (Pin 7)

In LS7184, this is the count direction indication output. When

A input leads the B input, the UP/DN output goes high in-

dicating that the count direction is UP. When A input lags the

B input, UP/DN output goes low, indicating that the count di-

rection is DOWN.

LS7183 - UPCK (Pin 8)

In LS7183, this is the UP Clock output. This output consists of

low-going pulses generated when A input leads the B input.

LS7184 - CLK (Pin 8)

In LS7184, 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 LS7184, the timing of CLK and UP/DN re-

quires that the counter interfacing with

LS7184 counts on the

rising edge of the CLK pulses.

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

LS7183 and LS7184 are CMOS quadrature clock converters.

Quadrature clocks derived from optical or magnetic encoders, when

applied to the A and B inputs of the

LS7183/LS7184, are converted to

strings of Up Clocks and Down Clocks (

LS7183) or to a Clock and an

Up/Down direction control (

LS7184). These outputs can be interfaced

directly with standard Up/Down counters for direction and position

January 2009

7183/84-011309-1

LSI/CSI

LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405

LS7183

LS7184

UL

®

A3800

RBIAS

A

B

MODE

DNCK

UPCK

PIN ASSIGNMENT - TOP VIEW

CLK

UP/DN

FIGURE 1

1

2

3

4

8

7

6

5

RBIAS

A

B

MODE

1

2

3

4

8

7

6

5