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This version is outdated by a newer approved version.This version (06 Mar 2018 17:57) was approved by Antoniu Miclaus.The Previously approved version (06 Mar 2018 16:48) is available.
This version is outdated by a newer approved version.This version (06 Mar 2018 17:57) was approved by Antoniu Miclaus.The Previously approved version (06 Mar 2018 16:48) is available.This is an old revision of the document!
Table of Contents
Activity: Temperature Control using Window Comparator
Objective
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, usually consisting of a pair of voltage comparators (inverting and non-inverting), in which the output indicates whether an input signal is within the voltage range bounded by two different thresholds. One which triggers an op-amp comparator on detection of some upper voltage threshold, VREF(HIGH) and one which triggers an op-amp comparator on detection of a lower voltage threshold level, VREF(LOW). The voltage levels between these two upper and lower reference voltages is called the “window”.
Materials
ADALM2000 Active Learning Module
Solder-less breadboard, and jumper wire kit
2 – AD8561 Comparators
1 – 2N3904 NPN transistor
2 – 1N914 small signal diodes
1 – LED ( any color )
3 – 10KΩ resistor
1 – 20KΩ resistor
1 – 470Ω resistor
Background
Consider the circuit presented in Figure 1.
Figure 1 Window Comparator
The circuit uses a voltage divider network, formed of three equal value resistors R1 = R2 = R3. The voltage drops across each resistor will also be equal at one-third of the reference voltage (VREF). Therefore, the upper reference (VREF(HIGH)) is set to 2/3VREF and the lower reference to 1/3VREF.
Considering that we use the When VIN is below the lower voltage level, (VREF(LOW)) which equates to 1/3VREF, the inverted output will be HIGH (non-inverted output will be LOW) and D1 will be forward biased, driving the Q1 transistor. When VIN exceeds this 1/3VREF lower voltage level, the first comparator detects this and switches the inverted output to be LOW (non-inverted output HIGH).
university/courses/electronics/electronics-lab-window-comp-tmp01.1520355423.txt.gz · Last modified: 06 Mar 2018 17:57 by Antoniu Miclaus