
USB-3101 User's Guide Specifications
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Note 4: Pull up and pull down configuration area available using the DIO CTL terminal block pin 54.
The pull down configuration requires the DIO CTL pin (pin 54) to be connected to a DGND pin
(pin 50, 53 or 55). For a pull up configuration, the DIO CTL pin should be connected to the +5V
terminal pin (pin 56).
Synchronous DAC Load
Table 7. SYNCLD I/O specifications
SYNCLD (terminal block pin 49)
Internal 100K ohms pull-down
Software selectable direction
Outputs internal D/A LOAD signal.
Receives D/A LOAD signal from external source.
4.0 V min, 5.5 V absolute max
1.0 V max, –0.5 V absolute min
Output high voltage (Note 5)
Output low voltage (Note 6)
Note 5: SYNCLD is a Schmitt trigger input and is over-current protected with a 200 Ohm series resistor.
Note 6: When SYNCLD is in input mode, the analog outputs may either be updated immediately or when
a positive edge is seen on the SYNCLD pin (this is under software control.) However, the pin
must be at a low logic level in order for the DAC outputs to be updated immediately. If an
external source is pulling the pin high, no update will occur.
Counter
Table 8. CTR I/O specifications
TTL, rising edge triggered
Counter read/writes rates
(software paced)
System dependent, 33 to 1000 reads per second.
System dependent, 33 to 1000 reads per second.
Schmidt trigger hysteresis
4.0 V min, 5.5 V absolute max
1.0 V max, –0.5 V absolute min
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