ADT14GP AD [Analog Devices], ADT14GP Datasheet - Page 15

• Manufacturer Part Number: ADT14GP
• Description: Quad Setpoint, Programmable Temperature Monitor and Controller
• Manufacturer: AD [Analog Devices]

Figure 30 illustrates the system described in the previous para-
graph, where each trip-point output corresponds to a 25% re-
duction in power when tripped. This is accomplished by the
dual rail-to-rail precision OP284 op amp configured as an in-
verting summer in the first stage, and as a V/I converter in the
second stage.
Suppose, however, that the heating element at a reduced power
level is unable to raise the ambient temperature to the desired
REV. 0
+5V
V
Figure 30. Combination Trip-Point Output
CC
ADT14
2.5V
TRIP3 (25%)
TRIP2 (50%)
TRIP1 (75%)
TRIP4 (0%)
REF
–15–
10k
10k
10k
10k
setting. This issue can be addressed by using a microcontroller
as shown in Figure 28. The microcontroller allows the time for
the given volume of material to heat up from a low trip-point
temperature to the next highest temperature trip-point to be
measured. If this time is too long, the microcontroller could add
additional power to the heater by altering a setpoint level.
2.49k
+5V
1/2 OP284
1/2 OP284
ELEMENT
HEATING
+5V
Q1
ADT14