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Buck-boost regulator is optimised for wearable health devices

The MAX20345 integrates a lithium charger and is the first device from the company to use an architecture that optimises the sensitivity of optical measurements for wearable fitness and health applications. The buck-boost regulator can be used for optical heart-rate and SpO2 sensing.


Currently, optical-sensing accuracy is impacted by a variety of biological factors unique to the user. Design challenges include increasing the sensitivity of optical systems, in particular the signal to noise ratio (SNR) but using traditional low-quiescent-current regulators have drawbacks such as high-amplitude ripple, low-frequency ripple and long-settling times. Using high-quiescent-current alternatives increases power consumption which reduces battery runtime or requires a larger battery. The MAX20345’s architecture is optimised for 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 which increase performance by up to 7dB (depending on measurement conditions).

The MAX20345 integrates a lithium-ion battery charger, six voltage regulators, each with ultra-low quiescent current, three nanoPower bucks (900nA typical) and three LDO regulators with low quiescent current (550nA typical). Two load switches allow disconnecting of system peripherals to minimise 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 favourable conditions.


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

A MAX20345EVKIT evaluation kit is also available.




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