Load Cell 3 Click is a compact add-on board that represents a weigh scale solution. This board features the PGA302, a low-drift, low-noise, programmable signal-conditioner device designed for various resistive bridge-sensing applications from Texas Instruments. It creates 2.5V of bridge excitation and a current output source with programmable current output up to 1mA. Two identical analog front-end (AFE) channels followed by a 16-bit Sigma-Delta ADC are available at the input, where each AFE channel has a dedicated programmable gain amplifier with gain up to 200V/V. It also comes with an on-chip temperature sensor and integrated EEPROM memory for device configuration, calibration, and user data. This Click board™ has many features that make it a perfect solution for weight scale and force-sensing applications that use strain gauge load cells and other general resistive bridge signal-conditioning applications.

Load Cell 3 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

Load Cell 3 Click as its foundation uses the PGA302, a high accuracy, low drift, low noise, low power, and versatile signal conditioner automotive grade-qualified device for resistive bridge pressure and temperature-sensing applications from Texas Instruments. The PGA302 provides bridge excitation voltages of 2.5V. The PGA302 conditions sensing and temperature signals by amplifying and digitizing through the analog front end chain and performing linearization and temperature compensation. The conditioned signals can be output in analog form, and, besides that, the signal data can be accessed by an I2C digital interface.

The PGA302 contains two separated analog-front end (AFE) chains with their gain amplifiers for resistive bridge and temperature sensing inputs. The resistive bridge input AFE chain consists of a programmable gain with eight steps from 1.33V/V to 200V/V. For the temperature-sensing input AFE chain, the PGA302 provides a current source that can source up to 1mA for the optional external temperature sensing available on the on-board terminal labeled with TMP+ and TMP-.

After the ADC decimation filters, the digitalized signals are sent to the linearization and compensation calculation digital signal logic. All required parameters for the linearization algorithm and other user data are stored in the integrated EEPROM memory. At the device's output, a 14-bit DAC is followed by a ratiometric-voltage supply output buffer with a gain of 4 V/V allowing a 0-5V ratiometric voltage system output available on the AN pin on the mikroBUS™ socket.

This Click board™ operates only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before use with MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

• Interface: Analog, I²C
• Compatibility: mikroBUS™
• Dimensions: 42.9 x 25.4mm
• Input Voltage: 5V
• ADC Resolution: 16 bits
• Operating Temperature Range: Min. -40°C, Typ. +25°C, Max. +150°C

• Schematic
• PGA302 Datasheet
• mikroSDK
• GitHub