Constant Frequency Current Mode Flyback DC/DC Controller in ThinSOT

The LTC3803-3 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 LTC3803-3 provides ±1.5% output voltage accuracy and consumes only 240μA of quiescent current. Ground referenced current sensing allows LTC3803-3-based converters to accept input supplies beyond the LTC3803-3’s absolute maximum VCC. A micropower hysteretic start-up feature allows efficient operation at high input voltages. For simplicity, the LTC3803-3 can also be powered from a high VIN through a resistor, due to its internal shunt regulator. An internal undervoltage lockout shuts down the LTC3803-3 when the input voltage is too low to provide sufficient gate drive to the external MOSFET.

The LTC3803-3 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 Powered Devices

* VIN and VOUT Limited Only by External Components

* Adjustable Slope Compensation

* Internal Soft-Start

* –55°C to 150°C Operating Temperature Range

* Constant Frequency 300kHz Operation