Synchronous buck controller serves extreme step-down ratios in industry and EVs
Compact and with an input voltage range of 6.0 to 75V, the L3751 synchronous buck controller serves different applications from industrial equipment to battery powered light electric vehicles, said STMicroelectronics.
The 3.5 x 4.5mm controller is also suitable for use in telecomms and networking equipment that feature 24V and 48V buses.
The L3751 has minimum on-time duration of 40ns, enabling it to support a low duty cycle which allows a large step-down ratio. It can power low-voltage devices directly without intermediate conversion which helps simplify circuit design, said ST, and also lowers bill of materials (BoM) costs. The controller integrates a 7.5V supply for the gate drivers.
In addition to having a wide supply voltage range, the L3751 has 100V-tolerant inputs that allow operation in harsh electrical environments. The switching frequency is adjustable from 100kHz to 1MHz, for use with a selection of external MOSFETs and passive components to optimise circuit size, performance and cost, said ST.
To enhance efficiency and minimize ripple, the L3751 operates in diode-emulation mode and with pulse skipping at light loads.
Protection includes thermal protection, input under-voltage lockout, constant current protection with hiccup mode and programmable current sensing. There is also an external enable pin and open-collector power-good indicator.
ST also provides the STEVAL-L3751V12, 100W evaluation board, to help designers accelerate device selection.
The L3751 is in production now and available in a QFN20 package with wettable flanks.
