Synchronous buck controller ideal for stepping down high-voltage battery supply

The STMicroelectronics L3751, which operates from a very wide input-voltage range of 6 V to 75 V, can step the input from a power distribution bus down to a power rail at 12 V or 5 V.

The L3751 from STMicroelectronics is a synchronous dc-dc step-down power controller which can support extreme voltage-conversion ratios with good power efficiency.Ā 

Operating from an input-voltage range of 6 V to 75 V, the L3751 provides an adjustable output of between 0.8 V and 60 V while switching at frequencies ranging from 100 kHz to 1 MHz. The controller is ideal for circuits that convert the output from a high-voltage battery or unregulated 24 V and 48 V bus to an applicationā€™s 12 V or 5 V power rail.Ā 

In diode emulation mode, the L3751 implements a pulse-skipping function which maximizes efficiency at light loads, and limits output-voltage ripple. Forced PWM operation over the entire load range holds the switching frequency constant, and also minimizes output-voltage ripple.Ā 

The controller features a Power Good output which validates the regulated output voltage: this is useful for implementing power sequencing during a digital IC power-up phase.Ā 

The L3751 includes 7.5 V gate drivers compatible with standard MOSFETs, eliminating the need for external gate drivers in a converter circuit. Embedded protection functions include output over-current, under-voltage lockout, internal voltage monitoring, and thermal shutdown.

Developers can use the ST eDesignSuite software tool to configure the L3751 buck converter for the application. The tool is available by clicking here.Ā 

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