Wavelength Electronics WTC3293, Datasheet And Operating Manual

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WTC3243 TEMPERATURE CONTROLLER
CHOOSE THE HEATING AND COOLING
CURRENT LIMIT RESISTORS — R
A
& R
B
Use Table 9 to select appropriate resistor values for R
A
and
R
B
. The Heat and Cool Current Limits graph, Figure 24,
shows the range of error for Table 9 .
Table 9. Maximum Output Current vs. Current Limit Resistor
MAXIMUM OUTPUT
CURRENT (A)
CURRENT LIMIT RESISTOR
( k Ω )
R
A
or R
B
0.0 1.58
0.1 1.66
0.2 1.74
0.3 1.83
0.4 1.92
0.5 2.01
0.6 2.11
0.7 2.22
0.8 2.33
0.9 2.45
1.0 2.58
1.1 2.71
1.2 2.86
1.3 3.01
1.4 3.18
1.5 3.36
1.6 3.55
1.7 3.76
1.8 3.98
1.9 4.23
2.0 4.50
2.1 4.79
2.2 5.11
Figure 24. Max Output Current Limits
Figure 25 shows fixed heating and cooling limits and is the
standard implementation.
Figure 25. Fixed Heat and Cool Current Limits
Figure 26 diagrams setting current limits independently using
trimpots. The 5 kΩ single turn trimpots shown adjust the
maximum output currents from 0 to 2.2 A.
Figure 26. Adjustable Heat and Cool Current Limits
DISABLING THE OUTPUT CURRENT
The output current can be enabled and disabled, as shown in
Figure 27 , using a Double Pole–Single Throw (DPST) switch.
In the following example, the effective limit resistance is 3 kΩ
or 1.3 A.
13 4 3
GND
WTC3243
LIMA LIMB
R
A
R
B
1.5 kΩ
DISABLE
R
B
1.5 kΩ
1.5 kΩ
R
A
1.5 kΩ
ENABLE
DPST SWITCH
Figure 27. Disabling the Output Current
13 4 3
GND
WTC3243
LIMA LIMB
R
A
R
B
CCW
13 4 3
GND
WTC3243
LIMA LIMB
R
A
R
B
CW
W
CCW CW
W
1.5 kΩ
1.5 kΩ
5 kΩ
SINGLE TURN
TRIMPOT
5 kΩ
SINGLE TURN
TRIMPOT