NewsSmall and flexible synchronous buck controller from STMicroelectronics handles extreme step-down ratios

Small and flexible synchronous buck controller from STMicroelectronics handles extreme step-down ratios

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With its compact dimensions and input voltage range of 6V to 75V, the L3751 synchronous control buck is ideal for various applications, from industrial equipment to battery-powered lighter electric automobiles. The 3.5mm wide x 4.5mm controller is also suitable for use in networking and telecom equipment that utilize common 24V and 48V buses. The minimum time-on-time is 40ns and a maximum on-time duration of 40ns, the L3751 is able to support extremely low duty cycles which allows for a high step-down ratio.

This permits powering devices with low voltage directly, without the need for intermediate conversions which can help simplify the design of circuits and reduces cost of materials (BOM) cost. The device incorporates the 7.5V supply for gate drivers. Alongside the ability to supply a broad voltage range it also has a 100V supply. L3751 includes inputs that are 100V-tolerant which allow for operation in tough electrical conditions. The frequency of switching can be adjusted from 100kHz to 1MHz allowing designers to maximize the performance, size and price, by selecting the external MOSFETs and other passive components.

To increase efficiency and reduce to reduce ripples, L3751 runs in diode-emulation mode , and also with pulse skipping in moderate loads. The L3751 has a wide range of protection features, such as temperature protection, in-put voltage undervoltage lockout, continuous current protection, Hiccup mode, as well as adjustable current sensing. Additionally, there is an Enable pin that can be connected externally and an open-collector indicator for power-good. The STEVAL L3751V12, 100W test board is designed to assist developers speed up their selection of devices for development of power supply.

Michal Pukala
Electronics and Telecommunications engineer with Electro-energetics Master degree graduation. Lightning designer experienced engineer. Currently working in IT industry.