Market research firm Gartner has previously predicted that the wearable fitness and health market will reach $14.4 billion in 2020 with approximately 190 million devices sold, and that power management chips will likely play a key role in many wearable designs.

While specialized healthcare wearables like Fitbit and Xiaomi Bands already exist, the market is expected to accelerate as watches now feature built-in fitness features. Samsung's Gear S2 watch saw a slight increase in sales in the domestic wearable/IoT market last year, and the anticipated release of the second-generation Apple Watch in March of this year suggests the wearable/IoT market will experience further volatility.

The biggest challenge for wearable devices is their ability to operate and monitor frequently, making low-power battery life a crucial priority. Furthermore, the importance of portability, including battery life, is driving the miniaturization and lightweighting of hardware. Furthermore, as they are gaining popularity as accessories, design considerations are also becoming increasingly important.

Accordingly, the two key factors engineers developing wearable and IoT devices must focus on are size and battery life. Minimizing size and extending battery life with low power consumption are key priorities. Maxim is making headlines with its products that meet both of these requirements. We met with Seongho Son, General Manager of Maxim Integrated Field Applications, to discuss the products and the core principles of wearable and IoT device development.

- I heard that the product being introduced this time is a PMIC product specialized for wearable/IoT devices. It's very interesting, could you give us a brief introduction to the product?

The product we're introducing today is the MAX14720 PMIC, which is suitable for wearable and IoT devices that use coin cells or regular batteries and need to operate for a long time on a single charge.

What challenges must a product suitable for wearables and IoT devices satisfy?

Wearable and IoT devices must be small, as they are meant to be carried on the body at all times. Furthermore, because they must detect body conditions and continuous signals, they must be able to operate for long periods of time on a single charge. However, as wearable and IoT devices become smaller and more functional, the number of discrete semiconductors used increases, inevitably taking up more PCB space. This raises issues regarding solution size and efficiency.

To summarize, low power and miniaturization are key for wearable and IoT devices. First, how can PMICs achieve low power?

The MAX14720 provides power regulators such as Buck-Boost, Buck, and Low-dropout regulator (LDO), all of which can operate with low quiescent current and have a battery seal mode to extend battery life.

- If you explain in detail the role of the power regulator and the battery's real mode

The aforementioned regulators offer 10x lower standby current than competitors, extending battery life in devices with multiple sleep/standby modes. Battery-seal mode completely disconnects the power rail using a power switch, reducing power consumption and extending battery life even when the device is not in use or stored for extended periods.

- Why is standby current important for wearables and IoT products?

Engineers may think that sleep mode has nothing to do with battery life because it is already low-power, but in fact, as you can see from the graph, sleep mode is the key to extending battery life by reducing the sleep mode current of wearable/IoT products. If we can save even a few nanoamperes of current in sleep mode, the overall battery life will increase significantly.


▲Power consumption rate by mode

- Besides low power consumption, what are MAXIM's unique strengths compared to other companies?

In particular, the MAX14720 features a built-in 1.2V buck that delivers 90% efficiency, reducing power consumption compared to applications using general LDOs. It also includes features such as pushbutton input monitoring, power-up sequencing, and voltage rail monitoring, providing flexibility in power control. For example, developers can implement a sequence interface that specifies how to handle the power key when it is pressed, or which power source should be turned on and off first, allowing for easier power control. Despite including all these features, its small size of 2.26 x 2.14 mm2 makes it suitable for wearable and IoT products with space constraints.

- Why was it possible to reduce the size despite all these features?

Maxim has specialized technology in integrated circuits, so it was able to create small-sized products that included multiple DC/DC and control blocks.

- Lastly, if you were to emphasize why engineers should choose this product,

As mentioned earlier, the MAX14720 PMIC integrates multiple components into a single, integrated chip, eliminating space constraints and enabling low-power control, making it ideal for wearables and the Internet of Things (IoT). Furthermore, by providing a direct IC, it offers a robust development environment that can significantly reduce development time and costs.