AS6040 Ultrasonic Flow Converter

In time conversion mode the CPU is not active and the chip sends the raw time-of-flight data. It communicates to an external microcontroller via SPI interface. By means of the integrated pulse interface the AS6040 can run also in stand-alone mode.

The analog front-end is supported by an integrated charge pump to provide a programmable fire voltage in the range from 6 V o 17 V with a frequency from 50 kHz up to 1 MHz. The integrated PGA gain factor can be adjusted from 2 to 250. The first hit level detection starts with a programmable offset up to 220mV. After this is set down to 0 mV, the AS6040 can measure up to 31 zero crossings within a single receive burst. The front end achieves in single shot less than 300 ps rms noise single shot with good 500kHz transducers. The first-hit pulse width information and the amplitude can be used to regulate the first hit level, but also to get information about situations with bubbles or empty tubes. It comes in a compact QFN48 package and allows compact designs thanks to a small number of external components.

FEATURES

• High performance + ultra-low power 32-Bit CPU with:
• 120 * 32 NVRAM (non-volatile RAM) for user firmware parameter & data
• 3968 * 8 bit NVRAM (non-volatile RAM) for user firmware program code
• 4k * 8 ROM for system task code and special flow library code
• 50 kHz to 1 MHz at 6 V to 17 V drive voltage, generated from battery supply
• Integrated PGA, gain 2 to 200
• First hit level and phase detection
• Amplitude measurement
• Up to 31 zero crossing measurements
• Precision time-to-digital converter and low noise frontend with < 50 ps single shot
• Ultra low power consumption
• SPI serial interface

BENEFITS

• Single-chip solution provides ready flow information
• System design compatible with meachanical meters
• High flexibility in choice for external µP handling communication and further data management
• Operation from battery
• Precision down to low flow rates
• Leakage detection
• Handles weak signals for small transducers and multiple reflections
• Compact design
• Low BOM

APPLICATIONS

• Residential Gas Meters
• Industrial Gas Meters
• Clamp-on Water Meters
• Volume Counters