The PDr2 is an optically isolated power driver for solenoids, valves, DC heaters,
DC motors, and other DC loads. It provides a stabilized current output from
0 to 2.5 amps, or more. The current output is in proportion to an analog control
voltage. That voltage can be provided by an analog output from a Lawson Labs,
data system, or from any other source.
A proportional valve, a fan motor, and a heating element are examples of loads
that can be controlled with resolution matching the analog control voltage. A
Lawson Labs data acquisition system and a PDr2 can replace expensive loop
controllers in many applications.
SPECIFICATIONS
Output up to 2.5 amps, or more, at 8 to 24 volts, isolated or not
Input power supply, 8 to 20 volts, reverse-protected
Input control voltage 0-5 volts (or 0-10 volts)
Input control voltage impedance 100K
Efficient, so that no extra cooling is needed. Only 5 deg C temperature
rise in still air driving a 1 Amp load
Power input current 6 ma typical at 1500 Hz modulation frequency
Modulation frequency is preset, and can be adjusted to suit
Load can be inductive or resistive
Built-in freewheeling diode for inductive loads
Gain is adjustable via on-board trim potentiometer, 0 - 100% range
Output is monotonic
Linearity is excellent over the middle 90% of the range
SIZE
1.9" x 2.7" x 0.6"
Efficiency over 98%, no heatsink or fan needed
PRICE
$45.00
OPTIONS
An offset adjustment trimpot can be added
4-20 MA input can be added
The optical isolation can be removed, if it is not needed
Normally ON or Normally OFF versions available
Other variations include
Voltage Output
Higher Voltage or Current ratings
OPERATION
The PDr2 is ideal for use inside a control loop. The temperature, pressure,
position, etc. that is being controlled is sensed and read by the analog data system.
Then, the analog output can be adjusted according to a programmed set of rules.
The trimpot can be adjusted for the desired maximum current output with the
maximum voltage input.
The current output will be zero with 0 volts in.
There is a non-linear zone coming out of zero volts. Typically, above a 250 mv
control input (0 -5 volt range), the output is fully linear.
There may be a similar non-linear band as the maximum power is appoached.
Because the control is modulated, dithering in the hardware is not usually necessary.
