Automotive SoC Enables Precision Ultrasonic Sensing

29th September 2009

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Datasheet

Maxim has introduced the newest member of its MAXQ RISC microcontroller product line: the MAXQ7667 SoC (system-on-chip), mixed-signal microcontroller for ultrasonic sensor applications. A highly integrated DAS (data-acquisition system), this SoC provides a cost-effective solution for applications that must measure weak signals over long distances or identify multiple targets. Its integrated functions, moreover, allow designers to add intelligence to cost-sensitive sensor-conditioning applications. The MAXQ7667 is optimized 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 7mm x 7mm device integrates the main functional blocks required to accurately measure position, including burst control (pulse transmission), analog echo reception, digital signal processing, and a microcontroller. This advanced integration reduces system cost and increases sensor-mounting options.

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 optimize 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 32KB of flash, 4KB of data RAM, and 8KB of utility ROM. The microcontroller can be programmed to dynamically optimize parameters, vary threshold based on time and noise, optimize 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.