Analog Devices offer AD8232 power-saving heart-rate-monitor AFE


50% smaller, 20% less power

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The AD8232 Heart-Rate Monitor AFE

Analog Devices have introduced a low-power, single-lead, heart-rate monitor AFE (analog front end) IC for a wide range of vital-sign monitoring applications. The AD8232 is 50% smaller and uses up to 20% less power than competitive devices. The power, size, and level of integration enables designers to develop heart-rate and cardiac-monitor devices for use outside of critical-care settings in areas such as personal-health management and remote health monitoring. In contrast to similar devices often derived from existing clinical cardiac-monitor ICs, the AD8232 AFE meets ECG signal-conditioning requirements of emerging fitness, portable/wearable monitoring, and remote health-monitoring equipment. Unlike the topologies employed in many of today's AFE ICs, the AD8232's highly flexible analog filtering configuration incorporates a two-pole high-pass filter, tightly coupled with the IC's instrumentation amplifier architecture. An uncommitted op amp enables the user to employ multi-pole low-pass filtering techniques to remove line noise and other interference. By taking gain and implementing high-pass filtering in a single stage in the analog domain, the AD8232 can accommodate electrode DC offsets, while operating on a single supply voltage without sacrificing performance. With an analog output, system designers can pair the AD8232 with a discrete ADC or with a microcontroller with an embedded ADC. This provides designers with the flexibility to deliver a new level of value and performance for fitness and healthcare monitoring. "There is a growing demand for fixed, portable, and even wearable heart-rate monitors that provide vital-sign measurements for athletes in training, home fitness equipment, or remote health monitoring," said Analog Devices' vice president Patrick O'Doherty. "This level of non-diagnostic monitoring is subject to a unique set of design considerations, and ADI believes the AD8232 offers manufacturers a better partitioned, more balanced signal processing architecture with greater flexibility in terms of back-end component selection and filter design." In addition to the instrumentation and gain amplifier, the AD8232 heart-rate monitor AFE integrates a reference buffer, right leg drive circuit, and shutdown function. The AD8232 also includes user-selectable (AC or DC) leads-off detect circuitry that monitors when an electrode is disconnected from the patient or user, providing an alert to the system. This new heart-rate monitor AFE offers an innovative fast-restore mode that quickly and automatically recovers the cardiac signal in the event a user temporarily loses contact with an electrode during exercise or other activity, greatly improving the quality of the end-user experience. Analog Devices AD8232 product deeplink