Load Cell Adc Calculation

Figure 5 is a block diagram of a reference design a weigh scale system evaluation board designed at analog devices.

Load cell adc calculation.

If you were using a 5v excitation current with the same load cell your full scale would be 10mv and therefore you would be effectively loosing one bit of resolution. And lastly though there are many other less common load cell set ups there is a strain gauge load cell which is a mechanical element of which the force is being sensed by the deformation of a or several strain gauge s on the element. Strain gauge load cells. It interface with simple digital i o to any controller.

It consists of an ad7799 adc controlled by an aduc847 microcontroller. A conversion scale graphic for each load and millivolt output range combination entered is also displayed below the calculated values. Strain gauge load cell weighing systems convert weights into analog output signals that can be further conditioned to indicate weight in digital meters and control systems. While on the left side we have e e a a b and b.

The load cell will be connected with e e a and a. The ads1231 is a precision 24 bit analog to digital converter adc. Strain gauge load cells are by far the most common type of load cell based weighing system in 2010. With an onboard low noise amplifier onboard oscillator precision third order 24 bit delta sigma modulator and bridge power switch the ads1231 provides a complete front end solution for bridge sensor applications including weigh scales strain gauges and load cells.

Hx711 the hx711 is a 24 bit analog to digital converter adc. The other devices will be calculated the same way using the appropriate noise tables for the calculations. As you can see on the right side we have ground dt sck and vcc. If you are working with a standard 2mv v load cell and a 10v excitation current this will give you a full scale input range of 20mv at the ad7730.

The load cell can be directly interfaced to this adc. From equation 42 and supplying the values determined for a 2mv v sensitivity and 10kg load cell you should be able to achieve better than 1g resolution using the settings shown in this application.