CENTENT COMPANY
be set from one encoder count to a maximum of
±
128 encoder counts, depending on the
value of the Scaling resistor. In either case, the adjustment sensitivity has infinite resolution.
+2.5 VOLTS
GROUND
R1
P1
P1 = ADJUSTMENT POTENTIOMETER
(10K)
R1 = SCALING RESISTOR
(100K)
SCALING RESISTOR
1
5 7
4 6 8 10
2
3
9
Figure 5
Sine-cosine encoders usually require plus and minus power supply voltages for proper
operation. The CN0182 has an on-board –5 V Generator as well as a +5 V Generator to meet
the requirements of both types of encoders.
If a sine-cosine encoder is used, care must be taken to accurately adjust both channels to the
required
±
1 volt signal amplitude in order to take advantage of interpolated accuracy. Follow
the encoder manufacturer’s recommended calibration procedures.
If the Position Error Pin is driven, care must be taken to keep noise out of this node. The
input impedance is 100K ohms in parallel with 100 pF. Precautions include shielding the
leads and keeping their lengths short. Use the encoder power supply ground (Terminal 6) as a
common for external circuitry. Do not put any capacitors on the Position Error Pin.
Failure to follow these precautions will result in unstable operation and probable Fault
Protect shutdown.
CURRENT LIMIT:
Motor current is sensed across a Current Sense resistor located at the power supply end of the
MOSFET Bridge. The Current Sense resistor serves the dual purpose of sensing motor
current for current limiting in normal operation as well as sensing short circuit conditions for
the protection circuit.
Because of the location of the Current Sense resistor, the voltage is passed through the Level
Shift Circuit to reference it to ground. The motor current is available at the Current Monitor
Pin on the Option Header (Pin 5). The scale is 10 amps per volt.
Motor current is limited on a pulse by pulse basis by the PWM. The Current Trimpot located
on the side of the drive sets the current limit. The range is from zero to 20 amps. Generally,
the current should not exceed the motor’s rated stall current. Setting the current limit lower
will limit the motor’s available torque and thus its ability to follow Step Pulse commands.
7
Summary of Contents for CN0182
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