LFLS7083 / LFLS7084
Description:
These devices allow incremental shaft encoders to drive standard up/down
counters. Connect the encoder quadrature outputs to the A and B inputs. The
LFLS7083
outputs can connect directly to the up and down clock inputs of
counters such as 74193 or 40193. The
LFLS7084
outputs can connect directly
to the Clock and Up/Dn inputs of counters such as 4516 or 74169.
Attention:
The next generation Encoder to Counter Interface chips are now
available and recommended for new applications (see
the
LS7183 / LS7184
data sheet).
The
LFLS7083, LFLS7083-S, LFLS7084
and
LFLS7084-S
are all RoHS
compliant.
Encoder to Counter Interface Chips
Schematic:
Features:
RoHS compliant.
X4 or X1 resolution multiplication.
TTL and CMOS compatible.
Low power (micro-amps).
8-pin DIP or SOIC package.
No external clocks required.
Drive standard Up/Dn counters.
Monolithic CMOS.
Pin Descriptions:
Pin 1 (Rbias input):
Connect a resistor to ground for the internal current mirror which feeds the two internal 2-axis one-shots. The resistor value sets the width of the low-true
clock outputs. A typical value is 300kOhm which sets the output pulse width to 1µs and max A,B frequency to 250kHz. Minimum resistor value is 50kOhm.
See the Rbias table (next page) for other values. The chip's current consumption is inversely proportional to this resistance. Typical current is 40µA @ 100KOhm
and 6µA @ 2MegOhm.
Pins 4 & 5 (A & B inputs):
Connect to the A and B quadrature outputs of the encoder. Both inputs have debounce filters. Minimum pulse width is set at 160ns. There is no maximum limit.
Input current is less than 1 µA. The A and B inputs can be swapped to reverse the direction of the external counters.
Pin 6 (X4/X1 input):
A high level applied to this input selects X4 mode, a low level selects the X1 mode. Input current is less than 1µA. Do not let this input float. In X4 mode, a clock
pulse is generated for every transition of the A or B input. Note that there are 4 transitions per cycle of quadrature code. Thus, a 500 cycle/rev encoder will
produce 2000 counts/rev in X4 mode. In X1 mode, only one clock is generated per quadrature cycle.
LFLS7083 pin 7 (Down Clock output):
Normally high, low-true. The low level pulse width is set by pin 1. Down counts are enabled only when B leads A (clockwise rotation). In X4 mode, one pulse
is generated for each A/B state change. In X1 mode, one pulse is generated per quadrature cycle.
LFLS7084 pin 7 (Up / Down Clock output):
This output steers the external counter up or down. High = Up (A leads B), Low = Down (B leads A).
LFLS7083 pin 8 (Up Clock output):
Normally high, low-true. The low level pulse width is set by pin 1. Up counts are enabled only when A leads B (counter-clockwise rotation). In X4 mode, one
pulse is generated for each A/B state change. In X1 mode, one pulse is generated per quadrature cycle.
LFLS7084 pin 8 (Clock output):
Normally high, low-true. The low level pulse width is set by pin 1. In X4 mode, one pulse is generated for each A/B state change regardless of count direction.
In X1 mode, one pulse is generated per quadrature cycle. The external counter should count on the rising (high-going) edge of this output.
Surface Mount Package:
The 8-pin SOIC package has the same pin-out as the DIP version shown above.
Absolute Maximum Ratings:
Parameter
Operating temperature
Storage temperature
Voltage at any input
Supply voltage (Vcc)
Min.
0
-65
-.5
Max.
70
150
VCC+.5
10.5
Units
°C
°C
Volts
Volts
DC Electrical Characteristics for 5V Operation:
Parameter
Supply voltage
Supply current
Units
Notes
Volts
µA
A,B = 0Hz
Rbias=300k
X4/X1 logic low
1.4
Volts
X4/X1 logic high
3.7
Volts
A,B logic low
0.6
Volts
A,B logic high
3.3
Volts
Low output current
1.75
mA
Vout = 0.4V
High output current
1.0
mA
Vout = 4.75V
Use standard CMOS levels when operating with higher supply
voltages up to 10.5 Volts.
Min.
4.75
-
Max.
10.5
8.0
RBias Resistor Value vs. Timing:
Resistor
100kOhm
300kOhm
500kOhm
2MegOhm
10MegOhm
Pulse Width
400ns
1µs
1.4µs
5µs
25µs
Max A,B Freq
625kHz
250kHz
180kHz
50kHz
10kHz
US
digital
info@usdigital.com
www.usdigital.com
Local: 360.260.2468 Sales: 800.736.0194
Support: 360.397.9999
Fax: 360.260.2469
1400 NE 136th Ave.
Vancouver, Washington
98684
USA
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