BU33UV7NUX：Optimal Boost DC-DC Converter for Dry Cell ApplicationsHigh Efficiency Over a Wide Load Current Range Through Load Current Mode Switching

In mobile devices such as smartphones and wearable gear, lithium ion batteries and other rechargeable secondary batteries are primarily used. However, electronic products such as household remote controllers, electronic dictionaries, and various gadgets (toys, accessories) are more than ever using dry cell batteries, which afford higher convenience with respect to availability and the like. Fueling this trend are diversifying applications and expanding overseas markets in developing countries and elsewhere. In addition, applications are provided with increasingly sophisticated functions, and there is a redoubled trend toward still greater power use. For all these reasons, ever greater power-saving performance is being demanded of power supply ICs that use dry cells for power input.

The BU33UV7NUX can be used in two modes, according to the load current. The MODE pin can be used to switch between a low-power mode (maximum load current 50 mA, consumption current 7 μA, PFM control) and a high-power mode (maximum load current 500 mA, consumption current 13 μA, automatic PFM/PWM switching control).

To cite examples of remote controllers, there are high-functionality products that use LCD panels and the like, and then there are standard items that use only buttons; the high-functionality products will necessarily require more power than the standard devices. Power consumption and efficiency can be optimized by using low-power mode for standard devices that require less power, and employing high-power mode for high-functionality products that require comparatively more power. Thus high efficiency over a wide range of load conditions, including light loading conditions, can be achieved, with a maximum efficiency of 94%. Moreover, a single device can be adopted in a wide variety of applications, for further advantages with respect to material management.

＜Application Examples＞

• ・General applications using one or two dry cells (1 to 3 V), or one button-type lithium battery
• ・Electronic dictionaries
• ・Remote controllers
• ・Electronic gadgets (toys, accessories)
• ・Wearable devices
• ・Electric toothbrushes

A BU33UV7NUX-EVK-101 evaluation board for the BU33UV7NUX is available. The board manual is provided as a download, so that detailed specifications can be referenced.

Moreover, BU33UV7NUX samples and evaluation boards are being sold by online merchants, and can be
purchased in quantities as small as single units.