Flyback controller

Linear Technology has released the H-grade version of the LTC3803-3, a current mode flyback DC/DC controller in a 6-pin ThinSOT package.

The device is guaranteed up to +150 °C operating junction temperature and is suitable for motor vehicle and industrial applications subjected to high ambient temperatures. The device can be powered from an input voltage ranging from 9 to 75 through a series resistor clamped with the device’s internal shunt regulator. The controller is suited to 4:1 input voltage range isolated applications commonly found in 12 and 42 V motor vehicle requirements.

The constant 300 kHz operating frequency is maintained down to very light loads, minimising low frequency noise generation over a wide range of load current. With adjustable slope compensation, an LTC3803H-3 based power supply achieves fast transient response with minimum output capacitance.

An integrated soft-start function reduces inrush current and output voltage overshoot. A 100 mV current sense threshold allows the use of a very small current sense resistor even at high power levels to maintain high efficiency. A device-based designed does not require a minimum load on the output for stable operation and the output voltage is determined by selecting external components.

With its ultra low 40 µA start-up and 240 µA quiescent current, the IC maintains high efficiency at light loads, allowing the use of a high-value input resistor for low power dissipation and quick power supply start-up.