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university:courses:electronics:electronics-lab-window-comp-tmp01 [07 Mar 2018 12:20] – add hardware setup and procedure Antoniu Miclaus | university:courses:electronics:electronics-lab-window-comp-tmp01 [03 Jan 2021 22:21] (current) – fix links Robin Getz | ||
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===== Objective ===== | ===== Objective ===== | ||
- | The objective of this lab activity is to use two high speed voltage comparators as a Window-Comparator and program the [[http:// | + | The objective of this lab activity is to use two high speed voltage comparators as a Window-Comparator and program the TMP01 Low Power Programmable Temperature Controller using this approach. |
A Window-Comparator is a circuit configuration, | A Window-Comparator is a circuit configuration, | ||
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===== Window Comparator ===== | ===== Window Comparator ===== | ||
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==== Background ==== | ==== Background ==== | ||
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==== Procedure ==== | ==== Procedure ==== | ||
- | Use the first waveform generator (W1) as source to provide a Triangular signal with 5V amplitude, 100Hz frequency and 2.5V offset. | + | Use the first waveform generator (W1) as source to provide a Triangular signal with 5V amplitude |
Use the second waveform generator (W2) as 5V constant reference voltage. | Use the second waveform generator (W2) as 5V constant reference voltage. | ||
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On the plot the " | On the plot the " | ||
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+ | ===== Temperature Control ===== | ||
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+ | ==== Background ==== | ||
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+ | An example of a window comparator application is a simple temperature controller circuit (Figure 2). The temperature sensor, TMP01, has the dual comparator configuration of figure 1 built in. By choosing the proper values for R< | ||
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+ | The TMP01 is a linear voltage-output temperature sensor, with a window comparator that can be programmed by the user to activate one of two open-collector outputs when a predetermined temperature set point voltage has been exceeded. A low drift voltage reference is available for set point programming. By connecting the two open collector outputs together as a single wire OR output we can obtain a signal which is at a logic high when the ambient temperature is within the target window. | ||
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+ | <WRAP centeralign> | ||
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+ | <WRAP centeralign> | ||
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+ | ==== Programming TMP01 ==== | ||
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+ | In the basic fixed set point application utilizing a simple resistor ladder voltage divider, the desired temperature set points are programmed in the following sequence: | ||
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+ | 1. Select the desired hysteresis temperature. | ||
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+ | 2. Calculate the hysteresis current I< | ||
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+ | 3. Select the desired set point temperatures. | ||
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+ | 4. Calculate the individual resistor divider ladder values needed to develop the desired comparator set point voltages at SET HIGH and SET LOW. | ||
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+ | The hysteresis current is readily calculated. For example, for 2 degrees of hysteresis, I< | ||
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+ | V< | ||
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+ | V< | ||
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+ | R< | ||
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+ | R< | ||
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+ | R< | ||
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+ | The total R< | ||
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+ | I< | ||
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+ | Since VREF = 2.5 V, with a reference load resistance of 357 kΩ or greater (output current 7 μA or less), the temperature setpoint hysteresis is zero degrees. Larger values of load resistance only decrease the output current below 7 μA and have no effect on the operation of the device. The amount of hysteresis is determined by selecting a value of load resistance for VREF. | ||
+ | |||
+ | ==== Tasks ==== | ||
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+ | 1. Build the following circuit: | ||
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+ | <WRAP centeralign> | ||
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+ | <WRAP centeralign> | ||
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+ | Measure VPTAT output value and compute the actual measured temperature in degrees Kelvin and degrees Celsius. | ||
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+ | 2. Build the following circuit: | ||
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+ | <WRAP centeralign> | ||
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+ | <WRAP centeralign> | ||
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+ | 2.a. Identify the components and try to draw the circuit schematic. | ||
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+ | 2.b. Using the information provided by the breadboard circuit, compute the following parameters: | ||
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+ | * I< | ||
+ | * V< | ||
+ | * V< | ||
+ | * T< | ||
+ | * T< | ||
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+ | 2.c. How many degrees is the temperature setpoint hysteresis? How can you change this value? | ||
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+ | 2.d. How does the circuit work? When will LED1 (red) and LED2 (blue) turn on? Explain your answer. | ||
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+ | <WRAP round download> | ||
+ | **Lab Resources: | ||
+ | * Fritzing files: [[downgit> | ||
+ | * LTspice files: [[downgit> | ||
+ | </ | ||
+ | ===== Further Reading ===== | ||
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+ | Additional resources: | ||
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+ | * [[adi> | ||
+ | * [[adi> | ||
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+ | **Return to Lab Activity [[university: | ||
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