Step-down regulators offer 260nA quiescent current

Article By : EDN Asia

The S-85S1P series achieves 90.5% efficiency at 100μA load, allowing designers to extend battery operation time by up to 2.5 times.

Seiko Instruments subsidiary SII Semiconductor has introduced two series of step-down switching regulators that feature ultra-high efficiency for low-power consumption in wearable and IoT devices.

The S-85S1A series features the industry’s lowest quiescent current of 260nA and a resulting high efficiency of 90.5% at a 100μA load, according to SII Semiconductor. This allows design engineers to extend battery operation time by up to 2.5 times compared to conventional LDO regulators. The S-85S1A series enables extended operation of wearable and IoT devices powered by small-sized batteries, while the company's proprietary constant on-time (COT) allows the circuit to achieve fast transient response to load fluctuation.

SII Semiconductor also introduced the S-85S1P series, which features a power monitoring output function, which divides battery voltage input into fractions of half or one third. The connection of this output to a low voltage microcontroller A/D converter enables monitoring of the battery voltage, or input voltage to the regulator. Conventional designs use external resistors to divide the voltage for monitoring. The S-85S1P series allows for reduced external component count and less board space, while improving current consumption and accuracy when compared to the current conventional design, according to the company.

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Figure 1: The S-85S1P block diagram (Source: SII Semiconductor)

Both the S-85S1A series and the S-85S1P series feature a small package to help reduce circuit design size and thickness. The packages are respectively SNT-6A (1.80mm x 1.57mmm x 0.5mm) and SNT-8A (2.46mm x 1.97mm x 0.5mm).

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