COLUMN - Power management IC innovation for IoT / wearable devices.

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Self-current consumption of 260nA achieved!! ── Ultrahigh Efficiency Step-Down Switching Regulator Impact of S-85S1A

The S-85S1A is an ultrahigh efficiency step-down switching regulator newly developed by SII Semiconductor Corporation. Through innovative technology such as COT (Constant On-Time) control and low power technology, it has achieved self-current consumption of only 260 nA. The S-85S1A is attracting attention and expectation as a product that will significantly extend the battery operation time of wearable and IoT devices.

Breaks the limits of conventional regulators.

For conventional switching regulators, the self-current consumption is in the microampere order. As a result, in the area where output current is in the microampere order, self-current consumption influences the current consumption due to the external load, substantially lowering the power consumption efficiency.

For wearable and IoT devices, their limited volume does not allow large batteries to be used. Accordingly, to extend battery operation time, there is no way other than to reduce the overall power consumption. That is why active attempts have been made to achieve energy savings in processors, displays and wireless devices, etc.

However, processors, displays and wireless devices in the wearables devices do not operate continuously. There is usually a reasonable standby time. Moreover, wearable devices are ultra-low power consumption devices in the first place. If conventional switching regulators are applied to these devices, the power consumption of the regulators themselves becomes relatively high. As a result, even if energy-saving processors, displays and wireless devices are used, how to extend the battery operation time is still a big issue. In some cases, the use of common series regulators can result in lower power consumption.

SII Semiconductor’s S-85S1A is a new type of switching regulator that has resolved these issues fundamentally.

Its self-current consumption is the industry’s top class 260nA. It delivers dramatically improved efficiency when operating under light load of 1mA or less, and can achieve efficiencies of 90.5% with a load of 100μA. This enables designers and developers of wearable devices to extend the battery operation time by up to 2.5 times compared to common series products.

Comparing with Competitors’ switching regulators whose self-current consumption is reduced to the level of nanoampere order, S-85S1A is expected to improve battery operation time by 15% to 30%.

Combination of fast-transient response and space saving.

The features of the S-85S1A are not just limited to efficiency. The COT (Constant On-Time) control topology, developed by SII Semiconductor to achieve a self-current consumption of 260 nA, also enables a very fast-transient response to load fluctuations. This will allow the prevention of voltage reduction when load fluctuates, significantly contributing to the stable operation of devices.

SNT-6AWhile containing various protection circuits, the S-85S1A uses the ultra-small package SNT-6A of the industry’s smallest class. Its detailed size is 1.8 x 1.57 x 0.5 mm on its own. It can be contained on a circuit board of 4.5 x 2.0 mm (a standard mounting example) including peripheral circuits. This makes it easy for the S-85S1A to be embedded into wearable devices with extremely small volume. Moreover, the existing board area can be selected for the usage of the conventional regulators or S-85S1A, thus allowing for development of flexible product strategy of making the S-85S1A adopted model and other models separately.

Wearable devices have been progressing from smartglasses, smartwatches to hearable devices. In order to promote their widespread usage, battery operation time, fast response and downsizing are all important issues to be considered. SII Semiconductor expects that the technology of S-85S1A will make a contribution to the development of wearable and IoT devices.