Healthcare ICs
Volume 9, Issue 8 YOUR SEMICONDUCTOR SOLUTIONS RESOURCE

Industry-Leading Technologies in Battery-Operated, Diagnostic ECG Monitors

A battery-operated wireless ECG monitor must be lightweight yet rugged since it is typically carried in a pocket or in a pouch worn around the neck or waist. It must be cost-sensitive yet capable of providing diagnostic quality ECG traces. The signal conditioning challenges inherent in this application are primarily due to the small signal of only 0.2 mV to 10 mV peak-to-peak (average of 1.8 mV), the 0.05 Hz to 150 Hz bandwidth, and the presence of 50 Hz/60 Hz interference. Power consumption must be low to ensure long battery life.

Solution
ADI offers industry-leading technologies for battery-operated portable ECG monitors requiring high accuracy and reliability, while maintaining a competitive cost structure.

The AD8226 is a low cost, wide supply range, rail-to-rail output instrumentation amplifier that operates in tightly packed, zero airflow designs where low noise and common-mode rejection are needed. It operates on supplies ranging from ±1.35 V to ±18 V for dual supplies and 2.2 V to 36 V for single supply, and draws only 350 µA of supply current. It is designed with a minimum gain of 1 and can easily handle ±10 V signals. It is available in a space-saving 8-lead MSOP package and requires only one external resistor to set any gain between 1 and 1000. Pricing: $1.40.

The low power ADSP-BF524 Blackfin® processor with advanced peripherals and low standby power offers up to 400 MHz performance and up to 800 MMACS. The device offers HS USB OTG, host direct memory access (HDMA), a NAND flash controller, and the availability of up to 48 GPIO pins. Blackfin processors provide efficient computation power that can be used in digital filtering to remove power line interference and EMG artifacts—and to perform pacemaker detection in software. In addition, Blackfin can perform system tasks such as user interface management (LCD/touch screen), wired (USB), and wireless (Bluetooth, ZigBee, and proprietary) connectivity tasks, all within a single processor. ADSP-BF52x processors have low active power and standby power dissipation, enabling powerful computation abilities and system task execution for portable embedded devices. Pricing: contact ADI.

AD7980 The AD7980 16-bit, 1 MSPS PulSAR® ADC supports the ECG requirements of a small footprint and uncompromised performance at low power per conversion. Power dissipation scales linearly with throughput (7.0 mW @ 1 MSPS, 70 µW @ 10 kSPS). It operates from a single power supply and is available in a 10-lead MSOP or QFN (LFCSP). The SPI-compatible serial interface also features the ability, using the SDI input, to daisy-chain several ADCs on a single, 3-wire bus and provides an optional busy indicator. Using the separate supply VIO, the AD7980 is compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic. Pricing: $12.09.

For a more integrated solution, the ADuC7022 incorporates a 16-bit/32-bit microcontroller that has a high performance 1 MSPS multichannel ADC integrated on the same chip. The ADC provides the necessary dynamic range to meet medical standards and to detect very small ECG waveform changes. The ARM7 architecture has 32-bit registers enabling it to perform real-time FIR filters on the ECG signal. Pricing: $4.03.

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ECG Monitors

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