Banner MICRO-AMP Series - Manual (Page 15)

SUPPLY VOLTAGE: 5V dc
±
10% at less than 20 milliamps; 100
millivolts maximum ripple. Voltage must not exceed 6V dc, or be
connected in reverse polarity. Install a 0.1 microfarad capacitor as
close as possible to the supply pins of the MPC3 (across pins #1 and
#3) if voltage transients are anticipated.
OUTPUT CONFIGURATION: the outputs at pins #7 and #8 are
conventional CMOS buffered gates. The output at pin #7 is high in the
DARK condition and low in the LIGHT condition. The output at pin
#8 is low in the DARK condition and high in the LIGHT condition.
Each output will source or sink several milliamps.
CIRCUIT PROTECTION: outputs are short-circuit protected.
They may be shorted to either the positive or negative supply line
without damage. The emitter output at pin #5 is internally current-
limited, and may be grounded indefinitely. The "AID" output at pin
#6 is internally current-limited, and may be connected to the positive
supply indefinitely.
SENSITIVITY ADJUSTMENT: the value of the sensitivity adjust-
ment potentiometer, or of the fixed resistor if sensitivity adjustment is
not anticipated, is 2,000 ohms (2k
Ω
). This is the optimum value for
Banner sensors and for most phototransistors of other manufacturers.
In situations where very high gain photodarlingtons or very low gain
phototransistors or photodiodes are being used, Banner can help
determine the best value.
FREQUENCY ADJUSTMENT: the response time of the circuit is
10 milliseconds or 4 oscillator pulses. Since the demodulator is
digital, faster response times are possible by simply increasing the
frequency of the emitter oscillator. This is done by installing a resistor
("Rf" in the hookup diagram) from pin #2 to the positive supply (pin
#1). The value of the resistor is best determined empirically, by
observing the signal at pin #5 (with respect to ground) on an oscillo-
scope. The response time of the MPC3 is equal to the time required
for four pulses, and the repeatability of the response time is the time
for one pulse. The approximate value of Rf is 390k
Ω
for 5 millisecond
response, and 39k
Ω
for 1 millisecond response.
An internal emitter oscillator generates 30 microsecond pulses at a rate
of about 400Hz. When the frequency of the emitter oscillator is
increased, the automatic emitter power control reduces the magnitude
of the pulse current to the emitter so that it will not be damaged by the
increased duty cycle. As a result, the excess gain (and the range) of the
sensors will automatically be reduced. For this reason, the MPC3
should be operated at the slowest frequency (response time) that is
consistent with the application requirements.
INDICATOR: a constant current output is provided at pin #6 for a
customer-supplied indicator LED. This current is held to only a few
milliamps in order to minimize power supply requirements. If the
LED that is selected does not appear bright enough, Banner can
suggest or supply high-brightness indicators.
CONSTRUCTION: totally encapsulated circuitry in molded high-
impact polystyrene housing. Closed-end jacks for PC plug-in mount-
ing are included.
OPERATING TEMPERATURE:
-40 to 70 degrees C (-40 to 158 degrees F).
MICRO-AMP ® MPC3 Specifications
SP100 Series Sensors
MICRO-AMP ® System
MPC3 Miniature Modulated Amplifier for direct PC-board mounting
Model MPC3 is a modulated LED photoelectric amplifier which utilizes custom CMOS
integrated circuitry. It contains all the circuitry necessary to modulate nearly any Light-
Emitting Diode (LED) and to amplify and demodulate the light received by a
phototransistor. The outputs are conventional buffered complementary CMOS gates.
The MPC3 is designed to work with the Banner SP100 series miniature modulated remote
sensors. However, it may be used with nearly any LED and phototransistor pair, as supplied
by most major semiconductor manufacturers. The small size and low cost of the MPC3
permit its use in OEM equipment where conventional photoelectric controls are not
justified, or where non-modulated sensors are now being used. Typical OEM applications
include duplicating machines, semiconductor processing equipment, label sensors, vend-
ing machines, vibratory feeder controls, robotic sensors, and automatic testing equipment.
The MPC3 also contains the patented Banner "AID™" (Alignment Indicator Device)
circuitry, which shows the strength of the received signal in addition to indicating the state
of the outputs. This feature permits easy setup and alignment of the sensors, and also
provides a means for the ultimate user of the equipment to monitor its performance without
test instruments. An LED indicator is added (externally) to utilize the AID circuitry.
Amplifier sensitivity is adjusted with an external potentiometer or fixed resistor. Amplifier
response speed is set at 10 milliseconds. An optional frequency control resistor (R
f
) may
be used for faster amplifier response.
The circuitry of the MPC3 is totally encapsulated in a high-impact molded polystyrene
housing. It is designed for mounting directly to a printed circuit board. A set of eight
closed-back pin jacks is supplied to allow the MPC3 to plug into the PC board. A battery-
powered demonstration board, model MPC3-DB, is available for evaluation of the MPC3.
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