Wavelength Electronics LFI-3500 Series, User Manual

Page: 33 / 38

33
Pins 8 & 9: (On/Off Detect, Common) This pin is an open drain connection that
remains in a high impedance state when the output is disabled. When the
output is enabled, this output is forced into a low impedance state with respect to
the common connection (pin 9).
Pins 9 & 10 : (Common, Remote On/Off) These pins can be used to enable and
disable the output current source and directly effect the front panel Output On
LED. A normally open momentary switch with switch bounce less than
500 msec can be connected to these pins. An open drain or open collector
output from a digital section can be used to trigger this input also, if the signal is
momentary and does not exceed 500 msec.
Pins 11 & 15: (TE V, Monitor Common) This pin provides a buffered
measurement of the voltage across the thermoelectric (pins 1 and 2 on the
Output Connector) and is referenced to pin 15. Its transfer function is 1 V / V.
This output is internally limited to 10mA maximum output current.
Pins 12 & 15 : (TE I, Monitor Common) This pin provides a buffered
measurement of the current sourced to the thermoelectric through pins 1 and 2
of the Output Connector and is referenced to pin 15. Its transfer function is
1 A / V. This output is internally limited to 10 mA maximum output current.
Pins 13 & 15 : (Temperature Setpoint, Monitor Common) This pin provides a
buffered measurement of the temperature setpoint determined by the Adjust
Potentiometer on the front panel and is referenced to pin 15. Its transfer function
is dependent on sensor choice and is given in the following table. This output is
internally limited to 10 mA maximum output current.
Pins 14 & 15 : (Temperature Monitor, Monitor Common) This pin provides a
buffered measurement of the sensor voltage measured across pins 4 and 5 of
the Output Connector and is referenced to pin 15. Its transfer function is
dependent on sensor choice and is given in the following table. This output is
internally limited to 10 mA maximum output current. This output can be used to
measure output temperature that exceeds the display range as noted on page
35.
To convert the Temperature Setpoint and Actual Temperature Monitors to sensor
units of measure, use the following transfer functions:
TRANSFER FUNCTIONS:
Sensor Bias Current Conversions
Thermistor
100
µ
A 10 k
Ω
/ V
Thermistor
10
µ
A 100 k
Ω
/ V
AD590 or LM335 NA 100 Kelvin / V
RTD
1000
µ
A 1 k
Ω
/ V
NOTE!
The voltages on pins 11-15 are
also used to drive the front panel
3 ½ digit display. Faults or shorts
on these pins directly effect
measurements on the display.