Pressure Transmitter Solution

The pressure sensor is a kind of sensor most commonly used in industrial practice and instrument control. It is widely used in various industrial automatic control environment, including water conservancy and hydropower, railway transportation, automatic production control, aerospace, military industry, petrochemical, oil well, electric power, ship, machine tool, pipeline, etc.
Recommended chip: LH001-55
Pressure Transmitter Solution

Pressure sensor is the most commonly used sensor in industrial practice and instrumentation control, and is widely used in Various industrial automatic control environments, involving water conservancy and hydropower, railway transportation, production automatic control, aerospace, military industry, petrochemical, oil wells, electric power, ships, machine tools, pipelines and many other industries. At present, the pressure sensor has also been significantly improved in the application of the medical industry, such as precision, reliability, stability, volume and other parameters have achieved breakthrough development compared with the past, and in respiratory equipment, infusion pumps, pressure pumps, diagnostic equipment and a variety of Playing a key role in monitors, pressure sensors boost the process of medical digitization. What is a pressure sensor? A pressure sensor refers to a device or device that can convert a pressure signal into a usable and outputtable electrical signal according to certain rules, and is usually composed of a pressure sensitive element and a signal processing unit. It is mainly composed of a load cell sensor, a measurement circuit and a process connection (intake pressure sensor). Pressure sensor market research shows that in the global market, pressure sensors account for about 20% of the overall sensor market, second only to flow sensors, and are the second largest sensor product type. The global pressure MEMS market reached $1.685 billion and is expected to drop slightly to $1.645 billion in 2020 due to the COVID-19 pandemic. The overall market is expected to grow to USD 2.214 billion by 2026, at a CAGR of 4%. ADC (Analog-to-Digital Converter), as the core component of the industrial control measurement system, is responsible for converting the analog signal of the pressure sensor to the main control MCU for calibration and other series of processing.

Figure 1 Pressure Transmitter Scheme


LH001-55 pressure transmitter solution

LH001-55 launched by Linghui Lixin, is a low noise 24  Bit Σ △ADC, providing a complete high-resolution measurement solution. The most significant bit (ENOB) can reach 23 bits. Integrated multiplex selection MUX and gain-adjustable PGA for flexible processing of differential or single-ended signals. Programmable filters allow the user to optimally choose between resolution and output rate. The chip integrates a programmable excitation current source and a temperature sensor. It also integrates a  12  bit voltage output type DAC. 4-wire SPI  interface, supports daisy chain expansion of multiple  ADC  to achieve simultaneous sampling. Figure 2. Block diagram of the bit chip. Another highlight of this chip is that it can accurately measure absolute negative voltage signals less than -0.1V under the condition of positive power supply voltage.

Figure 2 Structure Diagram


Figure 3 is the evaluation board of LH001-55, which is mainly composed of AFE(LH001-55),  ; General MCU and other components. Linghui Lixin provides a full set of software demonstration solutions. The demonstration program can sample the ADC input signal and send the data through the 1500000 serial port baud rate. Use the serial port debugging assistant to read data. The data format is: channel, ADC CODE,   voltage (mV), and the routine also has DAC and current source output.

Figure 3 LH001-55 Evaluation board


Figure 4 Pressure Transmitter Application Example

Key Indicators for LH001-55

Low-noise programmable gain amplifier (PGA) and high-resolution 24-bit analog-to-digital converter (ADC )
    − Maximum Effective Precision (ENOB) 23 bits
    −Programmable gain: 1/2/4/6/8/12/24/48
    − 4 differential inputs or 8 single-ended inputs
    − Support gain error, offset error self-calibration
    − Maximum Integral Nonlinearity: 13 PPM/FS
    − Programmable output rate: 2.5SPS-30kSPS
    − Continuous sampling mode: 525µ A
    − Sleep current: 0.2 μA
12-bit Voltage Output Digital-to-Analog Converter (DAC)
    − Output range: 0~2.5V
    − Supports resistive loads up to 1kΩ, capacitive loads up to 200pF
Integrated temperature sensor
Integrated two programmable excitation current sources:
    − 100nA/50μA/100μA/250μA/500μA/ 750μA/1mA 
Built-in 16MHz oscillator, ±3% accuracy
    − Analog: 2.4V to 3.6V
    − Digital: 1.7V to 3.6V