Open-Loop Piezo Controllers
Chapter 5: Operation
Page 10
Rev C, July 7, 2015
5.5.
Setting the Output Voltage Limit
The MDT693B and MDT694B include a voltage limit switch on the rear panel that
can be used to limit the maximum output voltage to 75 V, 100 V, or 150 V. The
lower limit is intended for lower-drive-voltage piezos. Thorlabs ships the controllers
to operate at the 75 V limit by default. However, it can be easily adjusted, as
described below:
1. Determine the maximum allowable voltage for your piezo element
(V
PIEZO
). We recommend the following settings:
a. Use the 150 V limit when V
PIEZO
> 150 V.
b. Use the 100 V limit when 150 V > V
PIEZO
> 100 V.
c. Use the 75 V limit when 100 V > V
PIEZO
> 75 V.
2. Power off the MDT693B or MDT694B and disconnect the piezo(s).
3. Locate the Voltage Limit switch on the rear panel of the MDT693B or
MDT694B.
4. Adjust the switch to the desired limit setting determined in Step 1.
5. Turn the controller on. The onboard micro controller will automatically
configure the controller to the appropriate settings. The gain of the
EXT
input BNC connector(s) will vary depending on the gain setting. For the
150 V limit, the gain is 15 V/V; for the 100 V setting, the gain is 10 V/V;
and for the 75 V setting, the gain is 7.5 V/V.
5.6.
Using INT Adjustment Knob
The INT adjustment knobs manually control the output voltages for each channel
from 0 V to 150 V. This can be thought of as a DC offset voltage, since it is summed
with the external control voltage (up to a maximum control voltage of 10 V). Note
that changing the voltage through USB commands overrides the INT knob.
All adjustment knobs include a lockout feature to prevent accidental adjustment.
To adjust the voltage setting, the knob must first be pushed in to unlock it. On the
corresponding display, the right-most decimal point will blink after the knob is
pushed in, indicating that it is ready for adjustment. To lock the setting, press the
knob in again. The knob will automatically relock after 30 seconds of no activity.
The manual adjustment knobs are auto scaling: Adjusting the knob slowly will
adjust the output at the highest resolution, and adjusting the knob quickly will make
larger voltage adjustments.
Follow the procedure described on the next page for operation in this mode.
1. Attach a piezo to one of the high voltage output connectors on the rear
panel of the MDT693B or the front panel of the MDT694B.
Note:
The BNC center conductor is positive and the shield is at
ground potential. Be certain to match piezo polarity to the
connector since most piezo elements will be permanently
damaged if connected backwards.
Содержание MDT693B
Страница 1: ...MDT693B and MDT694B Open Loop Piezo Controllers User Guide ...
Страница 30: ...Open Loop Piezo Controllers TTN011225 D02 Rev C July 7 2015 ...
Страница 32: ...www thorlabs com ...