High voltage (HV) bucks are widely used to power smart home IoT devices, home appliances, auxiliary power for industrial power, and E-meters. They are simple in design, low cost and require very little board space. Many electronic products use Bluetooth® Low Energy (LE) to exchange data through PCs, smartphones, as well as dedicated Bluetooth LE gateways. Bluetooth Low Energy has become one of the most popular standards for IoT applications. Renesas created a smart switching application by combining our HV buck and RX23W 32-bit microcontroller (MCU). This reference design shows a simple and effective design for a wall switch for smart appliances.

System Benefits​:

  • Renesas high voltage buck key advantages:
  • Zero standby power, good efficiency from light load to full load
  • Improved EMI by jittering and improved gate drive
  • Audible noise-free operation by avoiding operation in audible range
  • Renesas RX23W 32-bit MCU with Bluetooth LE
  • Low power consumption in Tx and Rx and sleep mode
  • Supports capacitive touch




  • Building automation
  • Home automation

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AS107 Ground.171 Sheet.1940 Sheet.1941 Sheet.1942 Sheet.1943 Single component.177.1880 11pt text 11pt text Up arrow 1pt.133 Dotted left arrow 1pt Right arrow 1pt.125 WC# AS107 AS107 Status LEDs Block.120 Block.124 Status LEDs Status LEDs Sheet.1693 Sheet.1694 Sheet.1695 Sheet.1696 Right arrow 1pt.1711 Label text 10pt Right arrow 1pt.125.1735 Dotted right arrow 1pt Dotted Line 1pt Optocoupler Optocoupler Optocoupler Buck Regulator 2 Buck Regulator Buck Regulator Right arrow 1pt.125.1776 Buck Regulator 1 Buck Regulator Buck Regulator Sheet.1780 Plug Sheet.1782 Sheet.1783 Sheet.1784 Sheet.1785 Right arrow 1pt.125.1786 110V/230V 110V/230V AC from Main 110V/230VAC from Main Down arrow 1pt.127 Right arrow 1pt.125.1789 Line 1pt.126 Line 1pt.126.1791 Max 200mA Max 200mA Max200mA Optional ALS for Light Sensing Optional ALS for Light Sensing Optional ALS forLight Sensing Label text 10pt.1794 53.3mA 53.3mA 53.3mA 3.3V 57mA 3.3V 57mA 3.3V57mA 3.3V 54uA 3.3V 54uA 3.3V54uA Dotted down arrow 1pt 12V 12V 12V SPST NO Switch.208 Sheet.1872 Sheet.1873 Sheet.1874 Sheet.1875 Sheet.1876 Sheet.1877 Line 1pt.126.1878 Inductor Air Core.212 Sheet.1898 Sheet.1899 Sheet.1900 Sheet.1901 Sheet.1902 Sheet.1903 Sheet.1904 Sheet.1905 Sheet.1906 Right arrow 1pt.125.1907 Ground.171.1908 Sheet.1909 Sheet.1910 Sheet.1911 Sheet.1912 Label text 10pt.1913 12V Relay 12V Relay AC110V/230V AC110V/230V AC110V/230V Signal Ground Sheet.1921 Sheet.1922 Sheet.1923 Sheet.1924 Sheet.1925 Line 1pt.126.1926 Down arrow 1pt.127.1927 Down arrow 1pt.1928 Right arrow 1pt.125.1929 Line 1pt.126.1930 Light Sensor Light Sensor Light Sensor MCU MCU MCU MCU Subsystem component.197 GPIO GPIO Subsystem component.1684 GPIO GPIO Subsystem component.1685 GPIO GPIO Subsystem component.1686 I2C I2C Subsystem component.1687 GPIO GPIO Subsystem component.1688 CTSU CTSU Subsystem component.1962 Bluetooth® Bluetooth® Cap Touch Cap Touch Cap Touch 6-8 Buttons Cap Touch6-8 Buttons Touch Key Sheet.1726 Sheet.1727 Sheet.1728 Sheet.1729 Sheet.1730 Sheet.1731 Sheet.1732 Sheet.1733 Sheet.1734 Sensor Sheet.1749 Sheet.1744 Label text 10pt.1741 ( ( Label text 10pt.1742 ( ( Label text 10pt.1743 ( ( Sheet.1745 Label text 10pt.1741 ( ( Label text 10pt.1742 ( ( Label text 10pt.1743 ( ( Sheet.1931 Optional PIR Sensor for Occupancy Sensing Optional PIR Sensorfor Occupancy Sensing Motor Motor Sheet.1767 Sheet.1768 M M Optional Motor Controller Optional Motor Controller Motor for Smart Home Control (Curta... Optional Motor ControllerMotor for Smart Home Control(Curtain/Blind)
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