LTC3803 — Constant Frequency, Current Mode, Flyback DC/DC Controller

describe

^{The LTC®3803} is a constant frequency, current mode, flyback controller optimized for driving 6V rated N-channel MOSFETs in high input voltage applications. Constant frequency operation is maintained down to very light load conditions, resulting in less low frequency noise over a wide load current range. 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 that exceed the absolute maximum VCC of the LTC3803 _{. A micropower hysteretic start-up function enables efficient operation under high input voltage conditions. For simplicity, the LTC3803 can be powered from a high VIN} through a resistor due to its internal shunt regulator . When the input voltage is too low, an internal undervoltage lockout circuit shuts down the LTC3803, providing sufficient gate drive to the external MOSFET.

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

Features

V _IN and V _OUT are limited only by external components

Adjustable slope compensation

Internal soft start

200kHz constant frequency operation

± 1.5% reference accuracy

Current mode operation for excellent line and load transient response

No minimum load requirement

Low quiescent current: 240μA

Low profile (only 1mm in height) SOT-23 package

Encapsulation

Typical Applications