MAX1464 Smart Pressure Transmitter Design

Pressure transducer is the largest industrial automation instrument used in industry and its application range is very wide. According to ARC Advisory Group reported on pressure transducer of all the world, the saleroom of pressure transducer was 12.74 billion dollars on the world market in 2002 and 14.71 billion dollars in 2007. Chinese pressure transducer market in 2004 nearly reach 1.35 billion dollars, and in 2009, it is expected to be 2.31 billion dollars.At present, there are two different kinds of pressure transducers in the market. The one is high precision intelligent pressure transducer, their function are very large with high price; The other is simple pressure transducers, they have low price and simple structure with low precision and simple function.This thesis design the low price intelligent pressure transducer which can be used to measure the bottom hole pressure. MAX1464 is the core of the intelligent pressure transducer. The temperature sensor, ADC and DAC are integrated in it, so the size of the transducer and the consumption of power can be reduced. The pressure and temperature analog signals can be converted into digital signals. The temperature can be compensated by software and the transducer outputs 4 and 20 mA current. Its precision has reach 0.1%F.S.in 0～85℃.It is the first time that the MAX1464 is used for pressure transducer in the nation. It has accomplished following content:(1) The design of small-size. As the pressure transducer used to measure the oilfield downhole pressure, the size of the transducer is required strictly. The MAX1464 is the core of the intelligent pressure transducer. The temperature sensor, ADC and DAC are integrated in it, so the size of the transducer can be reduced. It can be programmed for digital filtering, linearization and temperature compensation, without additional compensation circuit, thus the hardware circuit is simplified, the size of pressure transducer must be reduced.(2) The design of high performance-cost ratio. Using diffused-silicon pressure sensor can reduce costs, and the control chip MAX1464 can be programmed to achieve software compensation without compensation circuit hardware, so the pressure transducer has high performance-cost ratio. (3) The design of Multi-output. Due to MAX1464 integrates four rail-to-rail op amps, PWM, SPI interface, In addition to the design standards 4～20 mA current signal output, It can also output as 1～5 voltage, PWM, 4-20 mA current loop and the SPI data communications.