Rms to dc converter using lm324

Your shoppingcart is empty. Continue shopping. Forgot your password? Display all pictures. The key feature of this IC is its very good linearity of the output voltage with respect to the RMS of the input signal. This is due to the innovative delta-sigma computational technique, used in this IC.

Besides high linearity, this IC also features a high accuracy, high signal bandwidth, and good thermal stability. It can be used to accurately measure the RMS value of various alternating signals. This product is no longer in stock. Availability date:. The minimum purchase order quantity for the product is 1. Total Save:. This IC uses the proprietary delta-sigma computational techniques to achieve a highly linear DC voltage output at its output in respect with the RMS of the input signal.

The RMS is typically associated with the alternating signals. The RMS or Root Mean Square is used to describe the power of the input signal: the RMS value of current is equal to a DC current value that would produce the same heat dissipation on the resistive load.

Therefore, it is often important to know the RMS value of the signal. As mentioned before, the LTC provides a highly accurate and linear conversion of the RMS value at its input, to a constant voltage at its output. The constant voltage directly depends on the RMS value of the input signal, thanks to the innovative sigma-delta conversion technique of the LTC, which is described in details within the LTC datasheet.

Due to a high output voltage linearity, no compensation elements are required, except a single filtering capacitor. This ADC uses the voltage at its power supply pin as a conversion reference. Note, however, that this will cause the reference ADC voltage to change accordingly. This should be accounted for when calculating the output value. The input signal can be connected to the two-pole input signal connector.

The LTC IC accepts both bipolar and unipolar signals at its input, thanks to the differential input. Key Features It offers an excellent linearity that allows direct application with no compensation elements required, a rail-to-rail common mode voltage, a true RMS-to-DC conversion with a minimum number of external components, a good thermal stability, a very wide signal bandwidth, and more.

The demo can run on all the main MikroElektronika development boards. It is also possible to get the averaged output DC signal voltage , with a minimalized noise. For more details check the documentation. It can operate from 50 Hz to 1 kHz with an error of 0. The input voltage range on the differential inputs IN1 and IN2 extends to the supply rails, and so in the non-symmetrical circuit shown here the voltage on IN1 can swing between 0 V and the supply voltage.

If the signal to be measured is AC only, then another coupling capacitor will be required. The input impedance is many megohms. So, from the above formulas and examples, we can prove that how a non-true RMS multimeter calculates AC voltage.

But this value is only accurate for pure sine waveform. Otherwise, we will get an error. Before doing the calculations for the practical application, some facts need to be known to understand the accuracy while measuring RMS voltages with the help of the AD IC.

The datasheet of the AD tells about the two most important factors that should be taken into account to calculate the percentage of error that this IC will produce while measuring RMS value, they are. By observing the curves on the graph, we can observe that the frequency response is not constant with amplitude but the lower the amplitude you measure in the input of your converter IC, the frequency response drops, and in the lower measurement ranges at around 1mv, it suddenly drops a few kHz.

I assume now you can understand the rest values. NOTE: The frequency response curve and the table are taken from the datasheet. In simple terms, the crest factor is the ratio of the Peak value divided by the RMS value. For example, if we consider a pure sine wave with an amplitude of.

You can clearly see that from the below image taken from wikipedia. The table below from the datasheet tells us that if the calculated crest factor is between 1 to 3, we can expect an additional error of 0. The below schematic for the RMS converter is taken from the datasheet and modified according to our needs.

As shown in the schematic, an input attenuator is used which is basically a voltage divider circuit to attenuate the input signal of the AD IC that is because the full-scale input voltage of this IC is mV MAX. Now that we have clear some basic facts about the circuit let us begin the calculations for the practical circuit.

Now if we put these values in an online voltage divider calculator and calculate, we will get the output voltage of 0. That is the output of the voltage divider circuit. That is the output voltage from the AD IC. Now you can see that the above theoretical calculation and both the multimeter results are close, so for a pure sine wave, it confirms the theory.

The measurement error in both the multimeter results is due to their tolerance and for demonstration, I am using the mains V AC input, which changes very rapidly with time.

At this point, I did not bother to use my hantek BL oscilloscope because the oscilloscope is pretty much useless and only shows noise at these low voltage levels.