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

• 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-

pulse width (Tow). For proper operation, the output clock

pulse width must be less than or equal to the A,B pulse

Supply Voltage positive terminal.

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

A

B

x4/x1

DNCK

UPCK

PIN ASSIGNMENT - TOP VIEW

CLK

UP/DN

FIGURE 1

1

2

3

4

8

7

6

5

RBIAS

A

B

x4/x1

1

2

3

4

8

7

6

5

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