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Monolithic current mode step-down switching regulator

Linear Technology has introduced the LT3653, a 1.2A, 1.5MHz monolithic current mode step-down switching regulator with a programmable output current limit. Typically, it is used with battery charger power path controllers to pre-regulate the output and optimise battery charger efficiency. Its operating input voltage of 7.5V to 30V makes the regulator suitable for a variety of input sources including unregulated 12V wall adapters, 24V industrial supplies and Firewire as well as automotive applications. Onboard input overvoltage lockout protects the device through input transients of 60V, such as those commonly found in automotive applications.

The regulator's control pin, Vc is available for external battery tracking, known as Bat-Track control. This function keeps the output voltage 300mV above the Li-Ion battery voltage, which minimises thermal issues while simultaneously optimising charger efficiency. Similarly, the regulator offers an adjustable output current limit which can be set between 400mA and 1.2A through an external resistor. The regulator does not allow reverse discharge from the battery to VIN, eliminating the need for a blocking FET. It also utilises a 1.5MHz oscillator, internal compensation and an internal boost diode to minimise the overall solution footprint. Combined with a 2mm x 3mm DFN package, the regulator offers a compact high voltage input regulator for battery charger applications. The industrial grade LT3653IDCB is tested to operate from a -40°C to 125°C operating junction temperature.