PMIC is sensitive for optical measurements in wearables

Battery time in always-on wearable and IoT devices can be extended, says Maxim Integrated Products, with the integrated MAX20345 power management IC (PMIC). It integrates a lithium charger and uses an architecture that optimises the sensitivity of optical measurements for wearable fitness and health applications, says the company.

In wearables, optical-sensing accuracy is impacted by the wearer’s biological factors. To increase the sensitivity of optical systems, in particular the signal-to-noise ratio (SNR), designers have used low quiescent current regulators but these degrade SNR on the wrist with high amplitude ripple, low frequency ripple and long settling times. High quiescent current alternatives overcome these drawbacks, but they must deal with increased power consumption, which reduces battery runtime or requires a larger battery. The MAX20345 features a buck-boost regulator based on an architecture optimised for highly accurate heart-rate, blood-oxygen (SpO2) and other optical measurements, says Maxim. 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 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 ultra-low quiescent current (as low as 550nA typical). Two load switches allow system peripherals to be disconnected to minimise battery drain. Both the buck-boost and the bucks support dynamic voltage scaling (DVS) to save power 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).

It is available now, and an evaluation kit (MAX20345EVKIT#) is also available.

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