Bluetooth 5.1 SoC: Ultra‑Compact, Low‑Cost Solution for IoT Devices

Bluetooth Low Energy (BLE) has become the backbone of the IoT ecosystem, enabling short‑range, low‑power wireless links that keep battery‑operated gadgets running for months or even years. The explosive growth of fitness trackers, smartwatches, and other wearables has accelerated adoption of BLE across the industry.

A typical Bluetooth device (Fig. 1) is composed of a host and a controller. The host runs the Bluetooth stack and host‑side application logic, while the controller handles baseband operations for either classic Bluetooth (BR/EDR) or BLE. Both communicate through the host‑controller interface (HCI).

Fig. 1: Block diagram of the Bluetooth single‑mode and dual‑mode architecture.

BLE first appeared in Bluetooth 4.0, with subsequent revisions 4.1 and 4.2 adding incremental refinements. The real leap came with Bluetooth 5, which introduced a 2 MB/s data rate, a four‑fold increase in coverage to 240 m, and significant power‑saving improvements.

Bluetooth 5.1, announced in late 2018, built on those gains by adding location capabilities. The standard supports two positioning techniques—angle of arrival (AoA) and angle of departure (AoD)—allowing devices to determine each other’s position with meter‑level accuracy.

Today most wearables rely on BLE because it offers a cost‑effective, ultra‑low‑power solution that can be powered by a tiny battery for months or even years. Dialog Semiconductor has introduced what it calls the smallest and most energy‑efficient Bluetooth 5.1 SoC, the DA14531. The accompanying module streamlines development and opens up broader opportunities for IoT deployments.

The SmartBond TINY SoC is built around a 32‑bit ARM Cortex‑M0+ core, with integrated memories and a comprehensive set of analog and digital peripherals. By tightly integrating these functions, Dialog reduces the footprint of BLE solutions while keeping performance high. In large volumes, the SoC’s BLE capability can be added for as little as $0.50.

Its 2.0 × 1.7 mm package makes the DA14531 ideal for space‑constrained devices such as electronic styluses, shelf labels, beacons, and active RFID tags for asset tracking. The chip also suits applications that require provisioning, like cameras, printers, and wireless routers.

The DA14531 extends wireless connectivity into the connected‑medical arena. Potential use cases include inhalers, medicine dispensers, scales, thermometers, and glucometers (Fig. 2).

Fig. 2: Block diagram of the DA14531.

Housed in a 2.0 × 1.7 mm package, the SmartBond TINY is roughly half the size of its predecessors, according to Dialog. The SoC needs only six external components—a single clock source and a power supply—to form a complete low‑energy Bluetooth system (Fig. 3). This minimal footprint enables designers to integrate the chip into virtually any RF‑monitoring design.

“The external components are really limited; two capacitors are required. The power inductor can be skipped under certain conditions,” said Adrie Van Meijeren, product marketing manager Americas, Bluetooth Low Energy, at Dialog Semiconductor.

Fig. 3: Alkaline battery cell powered system diagram — boost configuration.

The module’s design guarantees longevity and reliability even with small batteries, and it frees customers from the burden of certifying their own platforms, thereby saving time, effort, and cost. The DA14531’s integrated DC/DC converter supports a wide input range of 1.1 V to 3.3 V.

“Regarding batteries and the DC/DC converter, we can work with any 1.4‑V/1.5‑V battery in addition to 3‑V coin‑cell batteries. Because the boost converter is onboard, it reduces cost. The DC/DC efficiency depends slightly on the inductor quality, but you can achieve around 85 % efficiency,” explained Van Meijeren.

“The DC/DC feature is crucial, especially for disposable batteries. These batteries often have tiny capacities—around 15 mAh. The boost converter’s start‑up current limits the inductor and capacitors, and we provide a current limiter that can be set between 6 mA and 96 mA, allowing us to start from any battery, regardless of its condition,” he added.

With BLE’s ultra‑low power consumption, many applications can run on a single small battery for four or five years, which is essential for devices that exchange only small data bursts intermittently.

Dialog also offers the DA14531 SmartBond TINY Development Kit, which incorporates the SoC and provides two mikroBUS headers and an Arduino interface for expanded functionality (Fig. 4).

Fig. 4: DA14531 SmartBond TINY Development Kit Pro.

Bluetooth is present in roughly 8.2 billion devices worldwide, from smartphones to laptops. Cisco predicts that by 2020 more than 50 billion smart devices will be in use, with Bluetooth SIG supporting up to a third of them.

With billions of BLE‑enabled devices on the market, the range of applications is virtually limitless. Selecting BLE for a project requires careful consideration of form factor, electrical characteristics, desired functionality, software development tools, and technical support.