LS7083 Datasheet, PDF (1/4 Pages) LSI Computer Systems – QUADRATURE CLOCK CONVERTER

LSI/CSI
LS7083/7084
U_{® L LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 [phone] FAX [phone]}
A3800
QUADRATURE CLOCK CONVERTER
October 2000
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 (VDD-VSS)
• LS7083, LS7084 (DIP)
LS7083-S, LS7084-S (SOIC) - See Figure 1
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.
PIN ASSIGNMENT - TOP VIEW
RBIAS 1
VDD(+V) ₂
VSS(-V) 3
A4
8 UPCK
7 _DNCK
6 x4/x1
5B
RBIAS 1
VDD(+V) ₂
VSS(-V) 3
8 ^CLK
7 _UP/DN
6 x4/x1
INPUT/OUTPUT DESCRIPTION:
RBIAS (Pin 1)
Input for external component connection. A resistor con-
nected between this input and VSS 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 (TOW≤TPS).
VDD (Pin 2)
Supply Voltage positive terminal.
VSS (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.)
7083/84-100600-1
A4
5B
FIGURE 1
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.