Rev A: 0611
5/98
System Operation
TP04100A Interface
&
Applications
3-1 2.3.5
D
UT
thermal constant (20-500) (Setup Parameter)
Allows the operator to fine tune the value set by self-tuning. This applies to DUT mode operation only
Accepted values are 20 to 500 in increments of 1. This number is actually a small modification factor
applied to the system tuned (derived) PID (Proportional Integral Derivative) constants.
Since the DUT mode self-tuning routine derives optimum PID constants, the DUT thermal constant allows
the operator to over dampen or under dampen device temperature response.
The thermal constant mid-range (default setting) is 100: values lower than 100 are for under damping
device response and values higher than 100 are for over damping device response. Therefore this number
-is used as a way of tuning the system to the thermal time response of the user's specific device type.
The constant can be set to produce minimum over-shoot/maximum stability/slower time to temperature, or
set for moderate overshoot/moderate stability/faster time to temperature. These varying traits of
temperature control are up to the user.
When setting, use this simple rule of thumb: the larger the DUT thermal constant, the greater is the
damping; the lower the DUT thermal constant, the smaller is the damping.
3-1
2.3.6
Air-to-D
UT
rnax
difference
(OC)
(Setup Parameter)
Allows the operator to set a maximum limit on the difference between the air and DUT temperatures that
will occur when operating the system in "DUT control" mode.
Accepted values are any between 10 "C and 225 "C in 1 "C increments. When the system is shipped this
value is set to 225 "C to ensure minimum transition times between temperatures.
The software applies this value symmetrically as the maximum allowable temperature differential between
the air temperature and DUT temperature as read by the system. It will apply either in a positive or
negative manner depending on the direction of control for the DUT.
For example, if "Air-to-DUT rnax difference" is set to 10 OC, and the device is currently at 50 OC, and a
setpoint of 100 "C is selected, then the air temperature would only be allowed to drive 10 OC maximum
above the current DUT temperature.
Inversely, if a setpoint of
+25
"C is selected, and the device is currently at +50 "C, the air temperature
would only be allowed to drive 10 "C maximum below the current DUT temperature.
Important: note that this "Air-to-DUT rnax difference" feature works in coincidence with the "Air
temperature max"
upper
and "Air temperature min"
lower temperature limits
which continue to define
the upper and lower air temperature limits.
i
For example, if the upper temperature limit is set to +I50 "C, and the "Air-to-DUT max difference" is set
1
to 20
"C,
and the device is currently set at +I40 "C, and a setpoint of +I50 "C is selected, then the air
temperature would only be allowed to drive 10 "C maximum above the current DUT temperature to the
I
upper limit of +I50 "C.. Thus the DUT may not achieve, or may take a long time to achieve, the desired
1
setpoint.
i
Page
3-31
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