Two Independent Controllers for
Regulation of:
− Fixed 2.5-V and an Adjustable Output
− ±2% (Max) Regulation Across
Temperature and Load (1 mA to 3 A)
Adjustable Output Can Be Set Via an
External Reference Pin, Allowing for the
Creation of a Tracking Regulator
Great Design Flexibility With Minimal
External Components
Applications: High-Current, Low-Dropout
Regulators for:
− DDR/RDRAM Memory Termination
− Motherboards
− Chipset I/O
− GTLP Termination

description/ordering information
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 simply is the product of the RDS(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.