Column: Circuit drill
Heat
dissipation performance of a universal active filter
By Dr. Sulaiman Algharbi Alsayed, Managing Director, Smart PCB Solutions T
he UAF42, a highly versatile IC made by Texas Instruments, is a universal active filter, with the unique ability to adapt seamlessly to different
configurations, including but not limited to low-pass, high-pass, band-pass, or band-reject filters. Tis remarkable IC finds its application
primarily in audio systems, sophisticated instrumentation and advanced telecommunication systems, where signal filtering is not just essential but crucial. Not only does it provide high-quality filtering but with minimal distortion and noise, too, ensuring optimal signal quality. It operates efficiently across a remarkably broad frequency range, catering to a wide array of applications.
Moreover, its low power consumption makes it an ideal choice for battery- operated and power-efficient applications, where power integrity is of the essence. Another significant advantage of the
UAF42 is its standard IC packaging, which allows its effortless integration into various circuits, making it easy to use and reducing design complexity. Furthermore, its robustness and reliability across different operating conditions make it a vital component in filtering solutions. It consistently ensures high performance, regardless of the challenges posed by the operating environment, making it a reliable choice for signal filtering. Figure 1 shows a basic active filter
circuit with the UAF42. It accepts an audio signal via pin #3 and delivers three types of output signals: low-pass (pin #1), high-
pass (pin #13) and band-pass (pin #7). Simultaneous replacement of matching resistors R3 and R4, which set the frequency limits of the filters, is necessary to maintain system balance. Electronics designers value this circuit
for its compact size and diverse filtered outputs. However, its complexity raises questions about its thermal sensitivity to certain frequency inputs.
Experiment and results Te focus of this experiment is to determine the maximum heat dissipation value within the entire frequency spectrum and, specifically, how this maximum value varies with different R3 and R4 resistances. Hence, the values of resistors R3 and R4 were varied, both starting from 50kΩ, then gradually increased in 50kΩ steps to 500kΩ. A 1Vdc signal was also applied to each
resistor, to study the effects. Te input signal frequency was also varied, from 20Hz to 5kHz, at 100Hz increments. Te dissipated power for the UAF42 was then calculated with:
(Power of power supply) – (Power dissipated from all resistors in the circuit) = (Power dissipated from UAF42 IC)
Figure 1: UAF42 typical circuit
Tis equation accurately calculates the power dissipation of the UAF42 IC for each resistance value. At the same time, resistors R1 and R2, the power supply signal amplitude and ambient temperature were kept unchanged.
08 May 2024
www.electronicsworld.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48
