A DC/DC converter is a direct current (DC) power transformer circuit. In different electric vehicle power configurations, at least one DC/DC converter is required to connect the battery to the DC power line. A DC/DC converter can change the value of a DC voltage from one value to a different value by temporarily storing input power and then releasing it at an output of a different voltage. Energy storage devices are either magnetic field type energy storage devices (inductors, transformers) or electric field type energy storage devices (capacitors). The power flow between input and output can be controlled by adjusting the duty cycle (on/off time ratio of the switching tube). This is done to control output voltage, input current, output current or to maintain constant power. On electric vehicles, this converter is mainly used to supply auxiliary load equipment such as horns, LED lights and other peripherals.
ST advanced DC/DC converter empowers the development of electric bicycles
To alleviate the range anxiety of electric vehicle users, using a DC/DC converter is an ideal solution. STMicroelectronics has launched a new generation of highly integrated DC/DC conversion controller L3751, which improves the switching performance of discrete power devices. STMicroelectronics' controller chip uses high-performance gate drivers to control the high-speed switching operation of MOSFETs, reducing the size and radio emission of energy storage components. With its compact size and input voltage range of 6V to 75V, the L3751 is suitable for various applications ranging from industrial equipment to pure electric light vehicles. The 3.5mm x 4.5mm controller is also suitable for common 24V and 48V telecom and networking equipment.
The minimum on-time of the L3751 is 40ns, which supports a very low duty cycle, allowing a large step-down ratio, allowing designers to directly supply power to low-voltage devices without using intermediate power converters, which helps simplify application circuit design , reducing bill of materials (BOM) costs. The device integrates a 7.5V gate driver supply.
In addition to a wide power supply voltage range, the L3751 can also withstand an input voltage of 100V and can work in harsh electrical environments. Switching frequency is adjustable from 100kHz to 1MHz, giving designers the flexibility to choose external MOSFETs and passive components to optimize circuit size, performance and cost.
To improve energy efficiency and minimize ripple current, the L3751 adopts diode emulation mode with pulse skipping function at light load.
The L3751 provides comprehensive electrical protection functions for the application, including thermal protection, input under-voltage lockout, hiccup mode constant current protection, and programmable current sensing. The product also has an external enable pin and an open collector power good indicator.
The STEVAL-L3751V12 100W evaluation board helps designers accelerate device selection during power supply development.
The L3751 is now in production and comes in a wettable flank QFN20 package, which helps to check that the chip is well mounted.
