Switching regulator rides automotive fluctuations

The LT1977 is a high-voltage 500kHz step-down switching regulator with burst mode operation to keep quiescent current under 100uA.

The LT1977 operates within an input range of 3.3 to 60V, making it compatible with load dump or cold-crank conditions in automotive applications.

Its 1.5A internal switch can deliver up to 1.25A of continuous output current at voltages as low as 1.25V.

The LT1977 is the latest addition to Linear Technology's growing family of high-voltage switching regulators featuring burst mode operation.

Its ultralow quiescent current is well suited for applications such as automotive power systems, which demand always-on capability and optimum battery life.

The combination of its thermally enhanced TSSOP package and 500kHz switching frequency keeps external inductors and capacitors small, ensuring a very compact footprint and optimum thermal management.

The LT1977 uses a high efficiency 60V, 1.5A, 0.2ohm switch with the associated control and logic circuitry integrated into a single die.

Proprietary design techniques and a new high-voltage process enable high efficiency over a wide input voltage range, and its current mode topology enables fast transient response and excellent loop stability.

Efficiency is optimised over a wide output current range by employing burst mode operation at low currents, using the output to bias the internal circuitry and a supply boost capacitor to fully saturate the power switch.

Additional features include a power good flag with programmable threshold and timeout, as well as soft-start capability and thermal shutdown.

The LT1977EFE pricing starts at $4.00 each in 1000-piece quantities.

The LT1977IFE, which is tested and guaranteed to operate over a -40 to +125C operating junction temperature, is priced at $4.60 each in 1000-piece quantities.

Both versions are available from stock.