Constant Frequency Current Mode Flyback DC/DC Controller in ThinSOT

The LTC3803 is a constant frequency current mode flyback controller optimized for driving N-channel MOSFETs in high input voltage applications. Constant frequency operation is maintained down to very light loads, resulting in less low frequency noise generation over a wide range of load currents. Slope compensation can be programmed with an external resistor.

The LTC3803 provides ±1.5% output voltage accuracy and consumes only 240μA of quiescent current. Ground-referenced current sensing allows LTC3803-based converters to accept input supplies beyond the LTC3803’s absolute maximum VCC. A micropower hysteretic start-up feature allows efficient operation at high input voltages. For simplicity, the LTC3803 can also be powered from a high VIN through a resistor, due to its internal shunt regulator. An internal undervoltage lockout shuts down the LTC3803 when the input voltage is too low to provide sufficient gate drive to the external MOSFET.

The LTC3803 is available in a low profile (1mm) 6-lead SOT-23 (ThinSOT™) package.

Turn On Voltage

Frequency

LTC3803

8.7V

200kHz

LTC3803-3

8.7V

300kHz

LTC3803-5

4.8V

200kHz

Applications

* Telecom Power Supplies

* 42V and 12V Automotive Power Supplies

* Auxiliary/Housekeeping Power Supplies

* Power Over Ethernet

* VIN and VOUT Limited Only by External Components

* Adjustable Slope Compensation

* Internal Soft-Start

* Constant Frequency 200kHz Operation

* ±1.5% Reference Accuracy