Ultrasonic sensor IC

Test & Measurement

20 January 2010 Test & Measurement

Maxim’s newest member of its MAXQ RISC microcontroller product line is the MAXQ7667 SoC (system-on-chip), a mixed-signal microcontroller for ultrasonic sensor applications. A highly integrated DAS (data acquisition system), this SoC provides a solution for applications that must measure weak signals over long distances or identify multiple targets. Its integrated functions allow designers to add intelligence to cost-sensitive sensor conditioning applications. The device is optimised for automotive sensor systems such as EPA (electronic parking assist) and PDC (park-distance control); it is also well suited for industrial processing, automation and handheld applications requiring position measurement.

This 7 x 7 mm device integrates the main functional blocks required to accurately measure position, including burst control (pulse transmissiona), analog echo reception, digital signal processing and a microcontroller. The MAXQ7667 features a programmable burst-frequency generator to compensate for transducer tolerances, adjust frequency with temperature, and perform diagnostics. Programmable burst and duty cycles can optimise power to match environmental conditions. The echo receive path includes a variable gain amplifier, a 16-bit sigma-delta ADC, a digital bandpass filter to eliminate OOB (out-of-band noise), and a digital demodulator with lowpass filtering to create an echo envelope. Echo detection is supported by an interrupt-generating, 16-bit threshold detector with programmable threshold and hysteresis levels. The microcontroller can be used for additional signal processing, or it can act as the threshold detector.

The integrated 16-bit, 16-MIPS microcontroller supports 32 KB of Flash, 4 KB of data RAM, and 8 KB of utility ROM. The microcontroller can be programmed to dynamically optimise parameters, vary threshold based on time and noise, optimise frequency to match the transducer, and adjust power and threshold based on the location of targets. Additional features include a general-purpose ADC for diagnostics and temperature measurement, a LIN-compatible UART with address capability, three general-purpose timers with interrupt capability, a system timer, general-purpose I/O pins with interrupt capability, and single-supply operation.

The MAXQ7667 is available in a space-saving 48-pin LQFP package, and is fully supported over the -40°C to +125°C automotive temperature range. An evaluation kit is available to speed designs. This kit includes an evaluation board and a PC-based IDE (integrated development environment), which provides a debugger, assembler/linker, time-limited version of the IAR C-compiler, and simulator.

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Ultrasonic sensor IC

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