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The LFC789D25 is a dual linear FET controller that simplifies the design of dual power supplies. The device consists of two independent controllers, each of which drives an external MOSFET to implement a low-dropout regulator. One controller is programmed to regulate a fixed 2.5-V output, while the second controller can be programmed to regulate any desired output voltage via a reference input pin, allowing for the creation of a tracking regulator often needed for termination schemes. And, because heating effects of the external FETs easily can be isolated from the controllers, the controllers can regulate the output voltages to a maximum tolerance of ±2% across temperature and load.

The LFC789D25 allows designers a great deal of flexibility in selecting external components and topology to implement their specific power-supply needs. With appropriate heat sinking, the designer can build a regulator with as much current capability as allowed by the external MOSFET and power supply. And, because the dropout of the regulator is simply the product of the R_DS(on) of the external power MOSFET and the load current, very low dropout can be achieved via proper selection of the power MOSFET.

Packaged in 8-pin SOIC and space-saving TSSOP, the LFC789D25 is characterized for operation from 0°C to 70°C.