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| MAX35101超聲波熱量(流量)表解決方案 |
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| 文章來源： 更新時間：2015/1/7 17:16:00 |
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Maxim公司的MAX35101是內置了放大器和比較器的時間/數字轉換器,是超聲波熱量(流量)表完整的模擬前(AFE)解決方案.時間/數字轉換精度20ps,測量范圍高達8ms,單電源2.3V-3.6V工作,主要用在超聲波熱量表,超聲波水表和超聲波氣表.本文介紹了MAX35101主要特性和優勢,框圖,應用電路,以及MAXREFDES70#超聲波流量表主要特性,框圖,電路圖,材料清單和PCB元件布局圖.
The MAX35101 is a time-to-digital converter with built-in amplifier and comparator targeted as a complete analog front-end (AFE) solution for the ultrasonic heat meter and flow meter markets.
With a time measurement accuracy of 20ps and automatic differential time-of-flight (TOF) measurement, this device makes for simplified computation of liquid flow. Early edge detection ensures measurements are made with consistent wave patterns to greatly improve accuracy and eliminate erroneous measurements.
Multihit capability with stop-enable windowing allows the device to be fine-tuned for the application. Internal analog switches, an autozero amplifier/comparator, real-time clock (RTC), and programmable receiver sensitivity provide the analog interface and control for a minimal electrical bill of material solution. The RTC provides an event timing mode that is configurable and runs cyclic algorithms to minimize microprocessor interactivity and increase battery life.
Built-in arithmetic logic unit provides TOF difference measurements. A programmable receiver hit accumulator can be utilized to minimize the host microprocessor access and thus minimize current consumption.
For temperature measurement, the MAX35101 supports up to four (4) 2-wire PT1000/500 platinum resistive temperature detectors (RTD).
A simple 4-wire SPI interface allows any microcontroller to effectively configure the device for its intended measurement.
On-board 8KB user flash allows the MAX35101 to be nonvolatile-configurable and provide nonvolatile energy use data to be logged. Configuration can be recalled anytime with a SPI command.
MAX35101主要特性和優勢:
Early Edge Detect Ultrasonic Time-of-Flight
• Time-to-Digital Accuracy Down to 20ps
• Measurement Range Up to 8ms
• Multihit Capability
• Early Edge Detect to Provide Advanced Accuracy
• Programmable TOF Hit Accumulator
• Two Channels: Single-Stop Channel
• Stop-Enable Windowing with Edge Trigger Select
• Built-In Pulse Launcher with Programmable Frequency
• Autozero Receiver Comparator
• Programmable Acoustic Recovery Sensitivity
• Automatic Two-Pulse Algorithm for Differential TOF Measurement
Temperature Measurement
• Up to Four (4) 2-Wire Sensors
• PT1000 and PT500 RTD Support
Event Timing Mode
• Allows Automatic Measurement Cycles
• Minimizes Microcontroller Interactivity to Reduce Power Consumption
Tamper Detection
• Single Input Pin Detects Tamper and Generates Processor Interrupt
Power Consumption
• 2.3V to 3.6V Single-Supply Operation
General
• 8KB of Nonvolatile Flash Memory for Data Logging
• Built-in Real Time Clock for Time of Day Monitoring
• 4MHz Oscillator Can Be a Ceramic Device to Lower System Cost
• Small, 5mm x 5mm, 32-Pin TQFP Package
• 4-Wire SPI Interface
• -40℃ to +85℃ Operation
MAX35101應用:
Ultrasonic Heat Meters
Ultrasonic Water Meters
Ultrasonic Gas Meters
圖1. MAX35101框圖
圖2. MAX35101典型應用電路圖
MAXREFDES70#超聲波流量表
Accurate, cost-effective, ultrasonic flow meters key a transformation in liquid and gas flow measurement. Critical for revenue collection, leak detection and conservation of critical natural resources, flow meters lie at the heart of utility and industrial distribution systems of water, gas and heat. Mechanical flow meters, currently the most prevalent meter style, use moving parts to measure the velocity of a fluid in a pipe. These moving parts are subject to wear and lose accuracy over time, often requiring replacement within 10 years.1 The MAXREFDES70# ultrasonic time-of-flight flow meter by Maxim Integrated sends and receives ultrasound waves between piezoelectric transducers in both the upstream and downstream directions in the pipe. By measuring the TOF difference between the upstream and downstream wave travels, utilizing sophisticated digital signal processing techniques, a very accurate flow rate can be calculated.
The MAX35101 is the center of the heat/flow meter system. The MAX35101 integrates all the functions required for automatic TOF measurements, including the ultrasound pulse launching and detecting, TOF calculation, temperature measurement, and a real-time clock (RTC). The MAX35101 can work in various configurable automatic event timing modes, requiring very minimal interactivity from a host microcontroller, thus reducing the total power consumption of the system.
圖3. MAXREFDES70#超聲波流量表外形圖
圖4. MAXREFDES70#超聲波流量表系統框圖
MAXREFDES70#超聲波流量表主要特性:
High precision
Large flow rate range
Ultra-low power consumption (20 years of battery life)
Compact and low cost
MAXREFDES70#超聲波流量表應用:
Ultrasonic heat meters
Ultrasonic cooling meters
Ultrasonic flow meters
圖5. MAXREFDES70#超聲波流量表電路圖
MAXREFDES70#超聲波流量表材料清單:
圖6. MAXREFDES70#超聲波流量表PCB元件布局圖:頂層
圖7. MAXREFDES70#超聲波流量表PCB元件布局圖:底層 |
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