Boost converter cuts fuel consumption up to 15%

Editor, Automotive Designline

March 22, 2012

Editor, Automotive DesignlineMarch 22, 2012

International Rectifier has just introduced the automotive-qualified AUIR3240S battery power switch for internal-combustion-engine shut-off and restart (stop/start system) that can help reduce fuel consumption in automotive vehicles by up to 15%.

The IR® AUIR3240S is a highly integrated boost converter designed specifically for stop/start systems that halt the engine when a vehicle is stopped in traffic. This system requires a “board net stabilizer” using a power switch that disconnects the starter and main battery from the auxiliary electrical systems during engine start.

The AUIR3240S is capable of driving several MOSFETs in parallel to achieve very low on-state resistance (Rds(on)) with current consumption below 50 µA. The new device provides 15V on the output with a wide input voltage (4-36V). The AUIR3240S also features diagnostics on the output current and a thermal sensor interface for robust designs.

“Designing a boost converter with the requirement of low current consumption is very challenging using discrete components. The AUIR3240S makes the system robust, reliable, and cost effective by cutting down the number of components and the PCB space,” said David Jacquinod, product marketing manager for IR’s Automotive Products Business Unit.

The company says the closest competition must use separate, external components to turn off the MOSFET’s. The biggest challenge in this design was that it needs to always be on while performing all functions like monitoring gate voltage, etc. while maintaining low quiescent current.

The AUIR3240S is qualified according to AEC-Q100 standards, features an environmentally friendly, lead-free, and RoHS compliant bill of materials.


Part Number    Package    Input voltage    Output voltage    Operating current
AUIR3240S    SOIC8         4-36V               >11.5V              50 µA max.

A datasheet, qualification standards, Spice Model, and design tool are available on the International Rectifier website at

Availability and pricing
Pricing for the AUIR3240S begins at $0.85 each in 100,000-unit quantities. Production orders are available immediately.

Get a weekly highlights update from Automotive Designline delivered directly to your inbox by signing up for our weekly automotive electronics newsletter here.

Loading comments...