Tektronix Keithley 2268 Series, Справочное руководство

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Series 2268 850 Watt DC Power Supplies Reference Manual Local Operation
2268S-901-01 Rev. A / January 2015 53
USING THE EXTERNAL SHUTDOWN FUNCTION
Use the external shutdown function to enable or disable the output of the power supply via a
logic level signal. When the external shutdown is triggered, the power supply will display
SD
POL on the output voltage and current displays. The external shutdown is useful for making
adjustments to either the load or the power supply without shutting off the power supply or
for using the power supply as part of a larger test system in which digital or analog control is
required.
Activating the External Shutdown Functio
n
To activate the external shutdown function, use the AUX output supply provided on the
Analog Programming Connector J3. This input has a user selectable polarity with logic low
input from 0.0V to 1.2V and logic high from 2.0V to 15V. The control signal for this input
must be capable of sinking 10mA minimum. This input is also compatible with the use of dry
contacts, where a short is logic low and an open is logic high. The input lines of the shutdown
circuit are fully optically isolated.
Once the External Shutdown has been triggered, the display will blink the .
Controlling the External Shutdown Function
The external shutdown circuit accepts a voltage or dry contact control (high or low logic
level) to enable or disable the power supply output. Make connections for the signals at the
AUX Output and Isolated Analog Programming Connector on the rear panel. (See “AUX
Output and Isolated Analog Programming (ISOL) Connector” on page 87 for more
information.)
To activate the shutdown function:
Connect the control signal source to the Shutdown pin (J3.12) on the Aux Output and
Isolated Analog Programming Connector with the control circuit ground connected to
Isolated Ground pin (J3.6).
The External Shutdown pin is pulled high internally (normally high). Therefore, if this
feature is not used, the polarity should be set to 1 to avoid false triggering. (See “Defining the
Polarity of the External Shutdown Signal” on page 54 for instructions.)