Estimating Product life Span

In order to predict the lifetime of a product, manufacturers usually conduct accelerated temperature & Humidity test. We usually conduct the accelerated test under the conditions that are much more severe than the actual operating conditions and record test hours, time-to-failure. Then we estimate/ calculate the product life-span using Peck's Power Law.

In the below example, the estimated lifetime of the product under test is 12 months if it survives for 96 hours at 80 °C with 90% RH. Assuming the product normal upper operating limit of 40 °C and 50% RH, we have got acceleration factor 92.48.

Digital filtering technique , ADC Filter

A digital filter system usually consists of an analog-to-digital converter (ADC) to sample the input signal, followed by a microprocessor and some peripheral components such as memory to store data and filter coefficients etc.

Program Instructions (software) running on the microprocessor implement the digital filter by performing the necessary mathematical operations on the numbers received from the ADC.

Here is a simple digital filter which identifies and reject transient response signal. It basically returns average of best two samples of the last three. The third sample is discarded.

Algorithm:

1. Calculate the average of the last 3 samples

2. Identity the sample furthest from the mean value (which is the outlier)

3. Discard the outlier and average the remaining two samples

4. Returns float value of the averaged data (y(i)).

EMI Filtering and Noise Reduction Circuit Design Simulation

During EMI/EMC compliance test, it is important to identity/isolate the noise component and prevent it from spreading into the PCB board. PI-Filers with ferrite and ceramic caps are quite effective to remove differential noise for the required frequency band. When selecting a ferrite, always know the frequency of the unwanted noise. The impedance of the ferrite is a function of frequency, size, material and numbers of turns. Below is my choice of filtering circuit where there is limited board space.

To do fine-tuning of your filter, it is recommended to do AC analysis for the required frequency band. I usually use LTspice IV software for simulation which is free to download. Simulation result and schematics diagram are as below.

Download link for LTspice is here.....https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html