Maxim 公司的MAXQ7667是高性能低功耗的16位RISC MCU超声远距离测量解决方案,是智能系统级芯片(SoC),具有智能模拟外设,包括专用的超声突发发生器,包括LNA, Sigma-Delta ADC的回声接收通路,取样频率250ksps的5路12位SAR ADC以及用于ADC的能带隙基准电压源,定时器/数字I/O外设等.广泛应用在汽车泊车,汽车安全,工业过程,自动化和手持设备.本文介绍了MAXQ7667的主要特性, 功能方框图和典型应用电路,以及突发发送级, 回声接收通路和12位SAR ADC 方框图.
16-Bit, RISC, Microcontroller-Based,Ultrasonic Distance-Measuring System
The MAXQ7667 smart system-on-a-chip (SoC) provides a time-of-flight ultrasonic distance-measuring solution. The device is optimized for applications involving large distance measurement with weak input signals or multiple target identification. The MAXQ7667 features high signal to- noise ratio achieved by combining flexible electronics with the intelligence necessary to optimize each function as environmental and target conditions change.
An integrated burst signal generator and echo reception components process ultrasonic signals between 25kHz and 100kHz. Echo reception components include a programmable gain low-noise amplifier (LNA), a 16-bit sigma-delta ADC to digitize the received echo signals, and digital signal processing (DSP). DSP limits noise with a bandpass filter, and creates an echo envelope through demodulation and lowpass filtering. Input referred noise is a low 0.7μVRMS. A programmable phase-locked loop (PLL) frequency synthesizer supplies the reference frequency for the burst generator and the clock for the echo receiver’s digital filter. An embedded 16-bit MAXQ20 microcontroller (μC) controls all the preceding functions.
The μC optimizes the burst frequency and reception frequency for each transmission at any temperature. The MAXQ7667 achieves smart sensing by monitoring the echo signals and then actively changing the transmitted and received parameters to obtain optimum results. Digital filtering and burst synthesis do not equire CPU intervention. This leaves all the CPU power available for echo optimization, communication, diagnostics, and additional signal processing.
The MAXQ7667 operates with three different power supply voltages: +5V, +3.3V, and +2.5V. Two internal linear regulators allow operation from a single +5V supply when three external power supplies are not available. Alternatively, the MAXQ7667 can control an external pass transistor to allow operation from a single supply voltage of +8V to +65V or more, depending on the external component tolerance. The device is available in a 48-pin LQFP package and is specified to operate from -40℃ to +125℃.
MAXQ7667主要特性:
Smart Analog Peripherals
Dedicated Ultrasonic Burst Generator
Echo Receiving Path (Includes LNA, Sigma-Delta ADC)
5-Channel, 12-Bit SAR ADC with 250ksps Sampling Rate
Internal Bandgap Voltage Reference for the ADCs (Also Accepts External Voltage Reference)
Timer/Digital I/O Peripherals
High-Performance, Low-Power, 16-Bit RISC Core
Program and Data Memory
Crystal/Clock Module
16 x 16 Hardware Multiplier with 48-Bit Accumulator, Single Clock Cycle
Power-Management Module
JTAG Interface
Universal Asynchronous Receiver-Transmitter (UART)
Local Interconnect Network (LIN)
MAXQ7667应用:
Automotive Parking
Vehicle Security
Industrial Processing
Automation
Handheld Devices
图1.MAXQ7667典型应用电路/功能方框图
图2.MAXQ7667突发发送级
图3.MAXQ7667回声接收通路
图4.MAXQ7667 SAR ADC 方框图
