Compact Synchronous Buck Controller with Wide Input Voltage Range Designed for Industrial Equipment

Published  October 19, 2022   0
L3751 Synchronous Buck Controller

STMicroelectronics has launched the new synchronous buck controller L3751 that comes with compact dimensions and serves different applications from industrial equipment to battery-powered light electric vehicles. With an input voltage range from 6V to 75V, this 3.5mm x 4.5mm controller is also suited to use in telecom and networking equipment that features commonly used 24V and 48V buses. Moreover, to enhance efficiency and minimize ripple, the L3751 controller operates in diode-emulation mode and with pulse skipping at light loads.

This device integrates a 7.5V supply for the gate drivers and has a minimum on-time duration of 40ns, it can support an extremely low duty cycle thereby permitting a large step-down ratio. This allows powering low-voltage devices directly without intermediate conversion, which helps simplify circuit design and lower bill-of-materials (BOM) costs. It provides extensive protection functions, including thermal protection, input under-voltage lockout, constant current protection with hiccup mode, and programmable current sensing.

Key Features

  • Wide 6 V to 75 V input voltage range

  • Adjustable output voltage from 0.8 V to 60 V

  • 100 kHz - 1 MHz switching frequency range

  • 40 nsec minimum on-time for extreme duty ratio

  • Low dropout operation during line transient

  • Adjustable soft-start or input voltage tracking

  • Pulse skipping or forced PWM operation at light load

  • Power Good open collector output validates VOUT

  • 7.5 V gate drivers for standard VTH MOSFETs

  • Constant current protection with hiccup mode

  • Precision or lossless programmable current sensing

  • Improved line transient response

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, giving designers flexibility to optimize circuit size, performance, and cost, through the selection of the external MOSFETs and passive components.