Microcontroller Integrates Differential Amplifier

Jan 12, 2011 11:44 AM

Maxim Integrated Products extends its line of MAXQ mixed-signal microcontrollers with the MAXQ7670A, a complete system-on-chip (SoC), mixed-signal microcontroller that integrates all the functions needed to accurately measure small-amplitude differential analog input signals. The MAXQ7670A pushes mixed-signal performance of the previously introduced MAXQ7670 to the 12-bit level, enabling measurements in the microvolt range from various types of sensors, such as anisotropic magnetoresistive (AMR) sensors. AMR sensors are typically used for contactless sensing of linear or angular displacement in automotive or industrial applications.

The MAX7670A requires only 5mm x 5mm of board space, and offers on-chip programmable gain control on each input channel. This avoids the need for external amplification of low-amplitude signals, resulting in cost reduction and PCB area savings of up to 40%.

Designed to digitize and process signals in harsh, space-constrained environments, this SoC is ideal for automotive applications such as steering, braking, and throttle-position control, as well as industrial control applications such as valve positioning and shaft rotation. The on-chip RISC CPU and embedded CAN bus controller allow real-time data processing for smart sensor networks.

The MAXQ7670A features eight single-ended/four differential inputs, followed by a programmable-gain differential amplifier (1x or 16x) and 125ksps ADC with 12-bit resolution. It digitizes sensor outputs for very precise real-world measurements, monitors supply-rail voltage to respond to power-failure conditions, and integrates a watchdog timer to ensure reliable operation. Its digital interfaces consist of a CAN 2.0B controller, SPI(TM) interface, JTAG interface, and seven general-purpose I/Os. A general-purpose timer with capture, compare, and PWM capability is also provided.

The MAXQ7670A includes a 16-bit RISC MAXQ microcontroller core, which allows for single-cycle data fetch and execution at 16MIPS. Additionally, the device integrates 2KB of SRAM for data and 64KB of automotive-grade flash memory. In-system programming is supported for field upgrades from a built-in 8KB utility ROM. The user can prevent unauthorized access to flash memory through a hardware password.

The MAXQ7670A is available in a space-saving, 5mm x 5mm, 40-pin TQFN package, and is fully specified over the -40 degrees Celsius to +125 degrees Celsius automotive temperature range. Prices start at $3.58 (1000-up, FOB USA). An evaluation kit is available to speed designs. This kit includes an evaluation board and a PC-based integrated development environment (IDE). The IDE provides a debugger, assembler/linker, time-limited version of the IAR C compiler, and simulator.

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