Maxim APPLICATION NOTE 4364 Ultra-Low Quiescent-Current Linear Regulator for Automotive Air Bags
Apr 13, 2009
Abstract: This reference design shows how to increase the output current of the MAX15006/MAX15007 linear regulators to meet the power-supply requirements for an automotive air bag.
As the electronic content of automobiles continues to increase, designers of electronic control modules are challenged to deliver improved performance with an increasingly limited power budget. Modern cars include multiple electronic systems such as stereo and infotainment systems, wipers, car lighting systems, safety equipment such as air bags, and more. Given the cumulative demand these systems place on the automobile battery, designers must reduce the power consumption of each electronic system as much as possible, especially when the car ignition key is off and the car is parked.
Frequently, the battery has to supply quiescent power for multiple system operations when the automobile is off. To reduce power consumption during this condition, several power-saving modes have been introduced into the powermanagement blocks: shutting down the clock to the microprocessors, and disabling the converter circuits through the enable inputs are two common examples. There are, however, devices and functions—such as remote keyless entry (RKE) and security systems—that should always remain on, whether the power is supplied by the alternator or the
battery. Figure 1 shows a typical power-supply module for air bags. This application note presents a circuit using the MAX15006/MAX15007 linear regulators for reducing the quiescent current of automotive air-bag applications. In addition to offering an ultra-low quiescent current, these devices are capable of withstanding load dumps up to 45V, making them ideal for the harsh operating conditions of automotive environments. Additionally, they feature a low dropout voltage, wide input voltage range, thermal and short-circuit protections, and an enable input, making them particularly well suited for power-supply modules in automotive air bags.