Auto Electronics

Linear Tech voltage pre-regulator features output current limit

Linear Technology has introduced the LT3653, a 1.2 A, 1.5 MHz monolithic current mode step-down switching regulator with a programmable output current limit. The part can be used with battery charger power path controllers to pre-regulate output and optimize battery charger efficiency.

A 7.5 V to 30 V operating input voltage range allows the LT3653 to be used for a variety of input sources including unregulated 12 V wall adapters, 24 V industrial supplies, and Firewire, in addition to automotive applications. Onboard input overvoltage lockout protects the device through input transients as high as 60 V, such as those commonly found in automotive applications.

The LT3653's control pin is available for Bat-Track external battery tracking, a function that keeps the output voltage 300mV above the Li-Ion battery voltage to minimize thermal issues while optimizing charger efficiency. The device also offers an adjustable output current limit that can be set between 400mA and 1.2 A via an external resistor.

The LT3653 does not allow reverse discharge from the battery to VIN, eliminating the need for a blocking FET. It uses a 1.5 MHz oscillator, internal compensation, and an internal boost diode to minimize the overall solution footprint. Packaged in a 2 mm x 3 mm DFN, the LT3653 is priced from $2.50 in 1,000 piece quantities. An industrial-grade version, LT3653IDCB, tested and guaranteed to operate from a -40°C to 125°C operating junction temperature, is priced at $2.88 each. Both versions are available from stock.

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