MAX20345 features buck-boost regulator optimized for accurate optical heart-rate and SpO2 sensing for wearables and IoT
Designers of always-on wearable and internet of things (IoT) devices now have an easier way to extend battery runtime while shrinking form factor with the latest tiny, highly integrated power-management IC (PMIC) from Maxim Integrated Products. The ultra-low-power MAX20345 integrates a lithium charger and debuts a unique architecture that optimizes the sensitivity of optical measurements for wearable fitness and health applications.
In wearables, optical-sensing accuracy is impacted by a variety of biological factors unique to the user. Designers have been striving to increase the sensitivity of optical systems, in particular the signal-to-noise ratio (SNR), to cover a broader spectrum of use cases. Traditional low-quiescent-current regulators favored in wearable applications come with tradeoffs that degrade SNR on the wrist, such as high-amplitude ripple, low-frequency ripple and long-settling times. Some designers have even turned to high-quiescent-current alternatives to overcome these drawbacks, but they must deal with increased power consumption, which reduces battery runtime or requires a larger battery. The MAX20345 features a first-of-its-kind buck-boost regulator based on an innovative architecture that's optimized for highly accurate heart-rate, blood-oxygen (SpO2) and other optical measurements. The regulator delivers the desired low-quiescent current performance without the drawbacks that degrade SNR and, as a result, can increase performance by up to 7 dB (depending on measurement conditions).
The MAX20345 is also the latest in a line of ultra-low-power PMICs for small wearables and IoT devices that help raise efficiency without sacrificing battery runtime. To meet these needs, the MAX20345 integrates a lithium-ion battery charger; six voltage regulators, each with ultra-low quiescent current; three nanoPower bucks (900 nA typical) and three ultra-low quiescent current LDO regulators (as low as 550 nA typical). Two load switches allow disconnecting of system peripherals to minimize battery drain. Both the buck-boost and the bucks support dynamic voltage scaling (DVS), providing additional power-saving opportunities when lower voltages can be deployed under favorable conditions. The MAX20345 is available in a 56-bump, 0.4 mm pitch, 3.37 mm × 3.05 mm wafer-level package (WLP.)
Key Advantages
- Superior Performance for Optical Systems:
The integrated buck-boost regulator provides the low ripple at high frequency that will not interfere with optical measurements. These short settling times support the high-sensitivity optical-sensor measurements on wearables.
- Extended Battery Life:
Regulators with nanoPower quiescent current reduce sleep and standby power, which in turn extends battery runtime and allows for smaller battery size. High-efficiency regulators preserve battery energy during active states.
- Small Footprint:
By eliminating multiple discrete components, the MAX20345 provides a sophisticated power architecture for space-constrained wearable and IoT designs.
Availability and Pricing
- The MAX20345 is available at Maxim's website for $4.45 (1000-up, FOB USA) and is also available from authorized distributors
- The MAX20345EVKIT# evaluation kit is available for $57.00
