Linear Tech Flyback Controller Operates At 150°C Junction Temperature

Linear Technology Corp. announced the H-grade version of the LTC3803-3, a current mode flyback dc-dc controller in a tiny 6-pin ThinSOT™ package. This H-grade device is guaranteed up to +150°C operating junction temperature and is well suited for automotive and industrial applications subjected to high ambient temperatures. The LTC3803H-3 can be powered from an input voltage ranging from 9 to 75V through a series resistor clamped with the device’s internal shunt regulator. The controller is well suited for 4:1 input voltage range isolated applications commonly found in 12 and 42V automotive requirements.

The constant 300kHz operating frequency is maintained down to very light loads, minimizing 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 100mV current sense threshold allows the use of a very small current sense resistor even at high power levels to maintain high efficiency. An LTC3803H-3-based design does not require a minimum load on the output for stable operation, and the output voltage is determined by the selection of external components. With its ultralow 40µA start-up and 240µA 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.

The LTC3803H-3 operates and is guaranteed over an operating junction temperature of -40 to 150°C. Pricing starts at $1.63 each in 1,000-piece quantities.