Linear Regulators Fulfill Automotive Needs

Today’s autos often incorporate dozens of low-dropout (LDO) linear voltage regulators, for applications ranging from instrument clusters to body controllers to engine management systems. In virtually all cases, LDOs serve a critical function, providing a low-cost voltage output to devices that require fixed voltage.

“You tend to find LDOs near a vehicle’s microcontrollers,” notes Mark Gary, strategic marketing manager for linear voltage regulators at Texas Instruments. “In many applications, such as low-end audio systems, it’s a more cost-effective solution than a dc-to-dc converter.”

The biggest market for LDOs is in automotive body controllers, for such applications as brake lamps, head lamps, turn signals and interior lights. They’re also being applied increasingly to gages on instrument clusters, as well as on most car audio systems.

In many cases, LDOs are available as part of a power management IC. Here are two new products that incorporate LDOs as standalone products or as part of power management ICs.

TI Targets Harsh Environments

Texas Instruments’ new family of high-voltage input LDO linear regulators are aimed at automotive under-hood applications, where temperatures are high and conditions are harsh. “We can survive load dump from the vehicle battery, as well as short circuits, and other problems that can occur in an automotive environment,” says Mark Gary of TI. The family of devices offers a wide input voltage range of up to 45V. Members of the family are the first devices from TI to provide a direct connection to the vehicle battery. They can withstand load dump transient conditions, thus reducing the number of external components needed to protect the LDO. Additional key features include 450-750 mA maximum-rated output current, thermal shutdown and over-voltage protection. The new family of devices — which includes the TLE4275QKTTRQ1, TL750M05QKTTRQ1 and the TL760M33QKTTRQ1 — also offers 3.5, 5 and 8V fixed-output voltage versions.

Power Supply IC Includes LDO

Infineon Technologies’ new TLE7368 Supersonic power supply IC incorporates linear regulators designed for low-dropout operation. The linear regulators offer high-output voltage accuracies to meet the needs of current- and next-generation 32-bit microcontroller families. They also feature short-circuit protection in the form of an output current limit function. A power sequencing function provides a controlled power-up sequence for the output voltages. Voltages are regulated to within two percent. All the functions are contained in the TLE7368 power supply chip, which converts voltage supplies from standard auto batteries to the power levels needed to drive 32-bit MCUs. The power supply IC is targeted at such automotive applications as engine control, automatic transmission control, power steering and assorted under-hood functions.