Silicon Labs introduced an optical heart rate sensing solution designed to reduce the cost and complexity of wrist-based heart rate monitoring (HRM) applications. The module can be used across a wide range of wearables including activity-tracking fitness bands, pedometers and smart watches, and gym fitness equipment.
The Si1144 includes a low-power optical sensor module paired with an energy-friendly EFM32 Gecko MCU running Silicon Labs’ advanced HRM algorithm. The small-footprint module integrates an optical sensor, green light-emitting diode (LED), LED drivers supporting up to two external LEDs, analog-to-digital converter (ADC), control logic and an I2C digital interface.
According to Silicon Labs, 100 million units of HRM-enabled devices will be sold per year by 2018, with the majority of those units being wrist-based wearables. The Si1144 addresses this large and growing market across a wide range of wearables including activity-tracking fitness bands, pedometers and smart watches, in addition to providing HRM capabilities for gym fitness equipment, bathroom scales and geriatric monitoring devices.
Daniel Cooley, vice president of marketing for IoT products at Silicon Labs said: “Silicon Labs’ Si1144 HRM solution addresses the challenges of wrist-based heart rate measurement by providing an accurate, easy-to-implement and cost-efficient solution priced well below competitive offerings. Additional benefits of Silicon Labs’ HRM solution include industry-leading power consumption and a very small footprint, making the Si1144 module a very good fit for power-sensitive, space-constrained wearables.”
Key features of the Si1144-AAGX module include:
- Accurate sensing of weak blood flow signals on the wrist with exceptional performance rivaling chest strap HRM designs
- Choice of two algorithms to support static HRM and optional dynamic HRM using data from an external accelerometer
- HRM solution pairs optical module with a Pearl Gecko MCU containing a DSP-enabled ARM Cortex-M4 core for low-power, high-performance designs or with a Cortex M3-based Jade Gecko MCU for simpler, cost-sensitive designs
- Fully integrated HRM IC with green LED lens, high-sensitivity photodiode, low-noise ADC, LED drivers, optical blocking and host communications/interrupts
- Two LED drivers to support up to two external LEDs
- Ultra-low power consumption for long battery life in wearables: < 500 nA standby current with 1.71 V to 3.6 V supply voltage
- I2C serial communications with up to 3.4 Mbps data rate
- 10-lead 4.9 x 2.85 x 1.2mm LGA module package