Buck-boost regulator for wearable and IoT devices
Optimized for accurate heart rate and oxygen saturation detection

Maxim Integrated Korea released the ultra-small, highly integrated power management integrated circuit (PMIC) 'MAX20345' on the 10th.
Designers of always-on wearables and IoT devices can easily reduce form factor and extend battery life with the MAX20345.

The MAX20345 integrates a lithium charger and implements a unique architecture that optimizes optical measurement sensitivity for wearable fitness and health applications.

The optical sensing accuracy of wearables is affected by several user-specific biological factors. Designers are working to expand the range of wearable applications by increasing the sensitivity of optical systems, including the signal-to-noise ratio (SNR).

Wearable applications using regulators with low standby current suffer from low SNR accuracy on the wrist due to high amplitude, low frequency ripple, and long settling times.

Some designers use high standby current products to address these shortcomings, but this increases power consumption, shortens battery life, and requires larger batteries.

The MAX20345 is the first of its kind to integrate a buck-boost regulator with an innovative architecture optimized for high-accuracy heart rate, blood oxygen saturation (SpO2), and other optical measurements.

This buck-boost regulator, which delivers low ripple even at high frequencies, does not interfere with optical measurements and enables high-sensitivity optical sensor measurements in wearables with short settling times. This regulator delivers the low quiescent current performance designers expect without compromising SNR, improving performance by up to 7 dB depending on measurement conditions.

The MAX20345, the latest in a family of ultra-low-power PMICs for small wearables and IoT devices, improves efficiency without compromising battery life.

Regulators with nanopower standby current reduce power consumption and standby power, extending battery operating time and reducing battery size. High-efficiency regulator conserves battery energy during operation.

The MAX20345 integrates a lithium-ion battery charger, six voltage regulators with ultra-low quiescent current, three 900nA nanoPower bucks, and three 550nA ultra-low quiescent current LDO (Low Dropout) regulators.

Two load switches disconnect the system peripherals to minimize unnecessary battery drain.

Both buck-boost and buck support dynamic voltage scaling (DVS), which allows for additional power savings by using lower voltages under appropriate conditions.

The MAX20345 is available in a 56-bump, 0.4mm pitch, 3.37mm x 3.05mm wafer-level package (WLP).

“The market for wearable electronics for fitness and wellness is expected to grow to 114 million units by 2020,” said Kevin Anderson, senior analyst for power IC research at IHS Markit. “As the market grows, demand is also increasing for better and more accurate sensing technologies for measuring health signals such as heart rate and blood oxygen saturation.”

“The MAX20345 expands Maxim’s portfolio of ultra-low-power PMICs for wearable and always-on applications,” said Frank Dowling, director of business management for the Industrial and Healthcare business unit at Maxim Integrated. “It enables the highest sensitivity optical sensing in a wrist-worn form factor, enabling more accurate vital sign measurements.”