STMicroelectronics has introduced the L3751 synchronous buck controller for a range of applications from industrial equipment to battery-powered light electric vehicles. The 3.5 × 4.5-mm controller also can be used in telecom and networking equipment that feature commonly used 24-V and 48-V buses.
With a minimum ON-time duration of 40 ns, the L3751 can support an extremely low duty cycle, which permits a large step-down ratio, said ST. “This allows powering low-voltage devices directly without intermediate conversion, which helps simplify circuit design and lower bill-of-materials (BOM) costs.”
Key features include a wide input Voltage range from 6 V to 75 V, 100-V tolerant inputs that allow operation in harsh electrical environments, and an adjustable switching frequency from 100 kHz to 1 MHz. The adjustable switch frequency “allows designers to optimize circuit size, performance, and cost, through the selection of the external mosfets and passive components,” said ST.
The L3751 operates in diode-emulation mode and with pulse skipping at light loads to improve efficiency and minimize ripple. The device integrates a 7.5-V supply for the gate drivers.
Protection functions include thermal protection, input under-voltage lockout, constant current protection with hiccup mode, and programmable current sensing. It also supports an external enable pin and open-collector power-good indicator.
The L3751, available in a QFN20 package with wettable flanks, is in production. The device is priced from $1.36 for orders of 1,000 pieces. A 100-W evaluation board (STEVAL-L3751V12) also is available.