原标题：Maxim MAX35104气体流量系统级芯片(SoC)解决方案

　　Maxim公司的MAX35104是气体流量系统级芯片(SoC),用于超声波气体流量计和医用呼吸机的模拟前端(AFE)解决方案.具有高精度的流量测量,测量范围高达400μs,支持 PT1000和PT500 RTD传感器以及温度调节器,工作电压2.3V-3.6V,工作温度-40°C 到+85°C.本文介绍了MAX35104主要优势和特性,框图,以及评估板MAX35104 EVK主要优势和特性,框图,电路图,材料清单和PCB设计图.

　　The MAX35104 is a gas flow meter system-on-chip (SoC) targeted as an analog front-end solution for the ultrasonic gas meter and medical ventilator markets. With a time measurement accuracy of 700ps and automatic differen­tial time of flight (TOF), the device makes for simplified computation of gaseous flow.

　　Power consumption is the lowest available with ultra-low 62μA time-of-flight measurement and 125nA duty-cycled temperature measurement. Multi-hit (up to six per wave) capability with stop-enable windowing allows the device to be fine-tuned for the application. Internal analog switches, a configurable three-stage integrated operational ampli­fier chain amplifier, and an ultra-low input offset compara­tor provide the analog interface and control for a minimal electrical bill of material solution. A programmable high-voltage (up to 30V) pulse launcher provides up to 19dB of transducer launch amplitude adjustment to compensate for transducer aging and temperature, pressure, humidity affects. Early edge detection ensures measurements are made with consistent wave patterns to greatly improve accuracy and eliminate erroneous measurements. Built-in arithmetic logic unit provides TOF difference measure­ments and programmable receiver hit accumulators to minimize the host microprocessor access. For tempera­ture measurement, the device supports a single 2-wire PT1000 platinum resistive temperature detector (RTD) or NTC thermistor. A simple 4-wire SPI interface allows any microcontroller to effectively configure the device for its intended measurement.

　　MAX35104主要优势和特性:

　　High Accuracy Flow Measurement for Billing and Leak DetectionTime-to-Digital Accuracy Down to 700psMeasurement Range Up to 400μs

　　2 Channels: Single-Stop Channel

　　High Accuracy Temperature Measurement for Precise Flow CalculationsOne 2-Wire Sensor: PT1000, PT500 RTD, and Thermistor Support

　　Maximizes Battery Life with Low Device and Overall System PowerUltra-Low 62μA TOF Measurement and 125nADuty-Cycled Temperature Measurement

　　Event Timing Mode with Randomizer Reduces Host μC Overhead to Minimize System Power Consumption

　　2.3V to 3.6V Single-Supply Operation

　　High Integration Solution Minimizes Parts Count and Reduces BOM CostBuilt-In Real-Time Clock

　　Small, 5mm x 5mm, 40-Pin TQFN Package

　　-40°C to +85°C Operation

　　MAX35104应用:

　　Ultrasonic Gas Meters

　　Medical Ventilators

　　图1.MAX35104框图

　　评估板MAX35104 EVK

　　The MAX35104 evaluation kit (EV kit) provides the hardware and graphical user interface (GUI) software necessary to evaluate the MAX35104 time-to-digital converter designed for ultrasonic heat, water, and gas meters. The EV kit includes a MAX35104ETL+ installed, as well as the required USB-to-SPI interface needed to communicate with the IC. The USB-to-SPI master section of the EV kit, along with the EV kit software, provides a quick method to exercise the device’s functionality.

　　The EV kit can be powered by the USB to simplify an evaluation setup, but also comes equipped with banana jacks that enable an external supply, such as a battery, to power the system. Provided BNC connectors allow for quick connection to piezoelectric transducers housed in a spool body. The provided terminal-block connectors allow for easy connection to the two remote platinum RTDs.

　　评估板MAX35104 EVK主要优势和特性:

　　Easy Evaluation of the MAX35104

　　Two Piezoelectric Transducer Connections and Two RTD Connections Provided

　　EV Kit Hardware Optionally USB Powered (USB Cable Included)

　　USB HID Interface

　　Windows XP®- and Windows® 7-Compatible Software

　　RoHS Compliant

　　Proven PCB Layout

　　Fully Assembled and Tested

　　评估板MAX35104 EVK包括:

　　Circuit Board Including MAX35104ETL+ and USB-to-SPI Circuitry

　　Mini-USB Cable

　　Five Shunt Jumpers

　　图2.评估板MAX35104 EVK外形图

　　评估板MAX35104 EVK材料清单:

MAX35104.pdf

MAX35104EVKIT.pdf