ECG front end IC shrinks cardiac monitoring wearables

October 12, 2016 // By Graham Prophet
A low power, next-generation biopotential analog front end (AFE) which enables smaller, lighter, and less obtrusive cardiac monitoring devices with longer battery life, the AD8233 AFE from Analog Devices (Norwood, MA) is a fully integrated, single-lead electrocardiogram (ECG) front end designed in a single component.

Typically, ADI says, developers need to design ECG front ends from individual components, which can add incremental cost and design time. The highly integrated, out-of-the-box AD8233 AFE eliminates these costs and time.

The device’s 2.0 × 1.7 mm (WLCSP) size enables the design of wearable health devices that are smaller, lighter, and easier to wear. Bulky, heavy, and obtrusive monitors can be unpleasant for patients to wear and may even interfere with their everyday lives.

Longer battery life is another crucial attribute for cardiac monitors and is vital to ensure continuous monitoring that provides accurate data without the interruption of a recharge or battery replacement. The AD8233 AFE’s low microamp-range power consumption results in greatly extended battery life.

Along with its small size, the single-supply (1.7 V to 3.5 V) AD8233 features extremely low quiescent current of 50 µA (typical); lead on/off detection even while in shutdown mode (<1 µA); and 80-dB common-mode rejection ratio (DC to 60 Hz). Electrical noise, a critical specification for cardiac-monitoring devices, is below 10 µV from 0.5 to 40 Hz.

The AD8233 also allows for highly flexible filter configurations which are essential to consistent, confident operation in an inherently harsh electrical environment under a range of use cases: a two-pole adjustable high-pass filter, a three-pole adjustable low-pass filter with adjustable gain, and an RFI filter. For ease-of-use and flexibility, it also includes an integrated right leg drive (RLD) amplifier with shutdown plus an uncommitted op amp. Analogue Devices also offers an evaluation board, reference design, web based filter design tool and Spice model.

The IC is priced at $1.49 (1000); the evaluation board (AD8233CB-EBZ) is $46.27.

Analog Devices: www.analog.com/AD8233