ZHCSH81 December 2017 PGA302
PRODUCTION DATA.
The PGA302 is 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. The PGA302 accommodates various sensing element types, such as piezoresistive, ceramic film, and steel membrane. The typical applications supported are pressure sensor transmitter, transducer, liquid level meter, flow meter, strain gauge, weight scale, thermocouple, thermistor, 2-wire resistance thermometer (RTD), and resistive field transmitters. It can also be used in accelerometer and humidity sensor signal conditioning applications. The PGA302 provides bridge excitation voltages of 2.5 V. The PGA302 conditions sensing and temperature signals by amplification and digitization through the analog front end chain, and performs linearization and temperature compensation. The conditioned signals can be output in analog form. The signal data can also be accessed by an I2C digital interface and a GPIO port. The I2C interface can also be used to configure other function blocks inside the device. The PGA302 has the unique One-Wire Interface (OWI) that supports the communication and configuration through the power supply line. This feature allows to minimize the number of wires needed.
The PGA302 contains two separated analog-front end (AFE) chains for resistive bridge inputs and temperature-sensing inputs. Each AFE chain has its own gain amplifier. The resistive bridge input AFE chain consists of a programmable gain with 8 steps from 1.33 V/V to 200 V/V. For the temperature-sensing input AFE chain, the PGA302 provides a current source that can source up to 1000 µA for the optional external temperature sensing. This current source can also be used as a constant current bridge excitation. In addition, the PGA302 integrates an internal temperature sensor which can be configured as the input of the temperature-sensing AFE chain.
The digitalized signals after the ADC decimation filters are sent to the linearization and compensation calculation digital signal logic. A 128-byte EEPROM is integrated in the PGA302 to store sensor calibration coefficients and configuration settings as needed.
The PGA302 has a 14-bit DAC followed by a 4-V/V buffer gain stage. It supports industry standard ratiometric voltage output.
The diagnostic function monitors the operating conditions including power supplies overvoltage, undervoltage, or open AFE faults, DAC faults, and a DAC loopback option to check the integrity of the signal chains. The PGA302 also integrates an oscillator and power management. The PGA302 has a wide ambient temperature operating range from –40°C to +150°C. With a small package size, PGA302 has integrated all the functions needed for resistive bridge-sensing applications to minimize PCB area and simplify the overall application design.