Low-Power PMIC Enables High Sensitivity Optical Measurements

Maxim Integrated Products has introduced its latest tiny, highly integrated power-management IC (PMIC). 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. According to Maxim, 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 7dB.

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, 0.4mm pitch, 3.37 mm x 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.

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

Maxim Integrated | www.maximintegrated.com

 

Novel Wearable Optical Display

Trulife Optics together with the UK’s National Physics Laboratory has demonstrated a new type of transparent head-up display device.

(Source: TrueLife)

(Source: Truelife Optics)

According to Simon Hall, lead scientist of Adaptive Optics at the NPL the new technology is unlike existing solutions: “Google’s solution is effectively a prism; it’s like a half-silvered mirror that you’re looking into and the Epson Moverio uses an embedded, slightly different refractive index component in a very thick lens which is reflecting light travelling through the rather thick waveguide”.

This new component is set to transform the development of wearable augmented reality and head-up display devices. Jonathan Lewis, CEO at Trulife optics commented that, “The development of wearable augmented reality devices has been curtailed by the lack of an optical component that allows for the overlay of high-definition, full colour images. But with the launch of our optic, we are providing that missing piece in the augmented reality jigsaw.”

Light carrying the image information is transmitted into the first hologram and then turned through 90° through the length of the optical waveguide using total internal reflection before hitting the second hologram. Here it is turned a further 90° then projected into the human eye. This allows for overlaid transparent images to be projected from the centre of the optic in perfect focus. The image is transparent, enabling the overlay of information on whatever subject is being viewed. The optic itself is lightweight, less than 2mm thick, and can be easily mass-produced for consumer and industrial applications.

The device is available now and costs approximately $514 (£300) plus VAT per unit for developers creating prototype devices. The cost of the optic for devices to be made in commercial volumes will depend on the final application and device to be produced.

[via Elektor — Source: Trulife optics]

Two-Channel CW Laser Diode Driver with an MCU Interface

The iC-HT laser diode driver enables microcontroller-based activation of laser diodes in Continuous Wave mode. With this device, laser diodes can be driven by the optical output power (using APC), the laser diode current (using ACC), or a full controller-based power control unit.

The maximum laser diode current per channel is 750 mA. Both channels can be switched in parallel for high laser diode currents of up to 1.5 A. A current limit can also be configured for each channel.

Internal operating points and voltages can be output through ADCs. The integrated temperature sensor enables the system temperature to be monitored and can also be used to analyze control circuit feedback. Logarithmic DACs enable optimum power regulation across a large dynamic range. Therefore, a variety of laser diodes can be used.

The relevant configuration is stored in two equivalent memory areas. Internal current limits, a supply-voltage monitor, channel-specific interrupt-switching inputs, and a watchdog safeguard the laser diodes’ operation through iC-HT.

The device can be also operated by pin configuration in place of the SPI or I2C interface, where external resistors define the APC performance targets. An external supply voltage can be controlled through current output device configuration overlay (DCO) to reduce the system power dissipation (e.g., in battery-operated devices or systems).

The iC-HT operates on 2.8 to 8 V and can drive both blue and green laser diodes. The diode driver has a –40°C-to-125°C operating temperature range and is housed in a 5-mm × 5-mm, 28-pin QFN package.

The iC-HT costs $13.20 in 1,000-unit quantities.

iC-Haus GmbH
www.ichaus.com