Snapdragon Wear 3100 Extends Battery Life

Article By : Rick Merritt

Ultra-low-power co-processor hits market just before Apple's new watch

SAN JOSE, Calif. — Qualcomm added an ultra-low-power co-processor running a bare-bones RTOS to its latest chipset for smartwatches to extend battery life. The new 3100 chipset debuts two days before Apple is expected to announce a new version of its Apple Watch, the current leader in smartwatches and wearables generally.

Qualcomm claims that its Snapdragon Wear 3100 can deliver four to 12 hours longer battery life than its prior chipset. It can work for a month on a typical smartwatch battery if Google’s Wear OS is turned off, said the chip vendor.

Power savings come mainly from hosting basic watch functions on a new 40-MHz Arm M0 chip running at 0.6 V in a homegrown software environment described as a basic scheduler. In sleep mode, the 21-mm2 QC1110 draws just 130 µA, compared to about 1.2 mA for a typical Cortex-A7 used to run Wear OS.

Qualcomm estimates that consumers use the interactive functions that require Wear OS only 5% of the time, opening the door to power savings. Its main processor running Wear OS now uses four A7s running at 1.2 GHz, up from a single A7 in the previous chipset.

Users can switch in software between Wear OS and basic smartwatch modes to conserve battery life. In addition, the chip’s power management software can automatically shut down the A7 host and move work to the co-processor after a period of inactivity.

Qualcomm had to design a custom SRAM block to support the co-processor’s near-threshold operation. The co-processor also contains a custom block to listen for and detect wake words from a voice assistant.

The 3100 comes in versions supporting LTE, GPS, or Bluetooth and Wi-Fi. The 3100 host processor fits in a 10 x 10-mm package stacked with up to 1-GByte LPDDR3 memory. It supports a flash eMMC module of 8 Gbytes or more.

The chipset includes a new power management IC and a power amp made in a GaAs process. Prior chips used a CMOS power amp that supported envelope tracking but was less power-efficient.

Snapdragon Wear 3100 block diagram

A near-threshold controller is at the heart of the latest Snapdragon chipset for wearables. (Image: Qualcomm)

Still early days for wearables sector

It’s still early days for a smartwatch market that ships about 50 million units a year and is expected to nearly triple in three years. Last year, Apple’s success — in part with its first models with built-in LTE — pushed it into the lead in the overall wearables market.

Apple shipped about 17.7 million smartwatches last year of a total wearables market estimated at 115 million units, according to International Data Corp. Xiaomi and Fitbit were in a near tie for second place, shipping more than 15 million units each, including smartwatches, fitness trackers, and other devices.

In smartwatches, Samsung runs a distant second to Apple with devices based on the Tizen OS. Qualcomm claims that its chips run 80% of Wear OS devices, which trail Apple and Samsung in smartwatches.

“Apple has done a good job creating a good product and awareness, but [the Apple Watch] only works with iPhones, and we expect Android and iOS users to buy” 3100-based products, said Pankaj Kedia, who heads Qualcomm’s wearables group.

Growth potential is huge, said Kedia, considering that smartwatches still represent a small fraction of the 1.4 billion watches sold last year and the 1.5 billion smartphones sold annually.

Qualcomm counts among its smartwatch customers Asus, Huawei, LG, and more than a dozen fashion watch vendors. It expects to add new names to its list with the 3100, which is shipping now and should be in consumer products for the holiday season.

— Rick Merritt, Silicon Valley Bureau Chief, EE Times

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