Power infotainment systems with automotive buck regulator

May 14, 2014 // By Graham Prophet
A8585 from Allegro MicroSystems is an automotive buck regulator IC that is designed to provide the low quiescent current power supply requirements of next-generation car audio and infotainment systems.

The AEC-Q100 qualified device incorporates all the control and protection circuitry required for a high-current regulator with ±1.0% output voltage accuracy. It operates over a wide input voltage range from 4 to 35V, and offers a choice of pulse width modulated (PWM) or pulse frequency modulated (PFM) operating modes.

In PWM mode, the device employs current-mode control to provide simple compensation, excellent stability, and fast transient response. In low I Q (quiescent current) mode, the A8585 employs pulse frequency modulation (PFM) to draw less than 33 µA from an input of 12 V while providing an output of 5.0V/40 µA. Once operational, the A8585 will operate from an input voltage as low as 3.6V (falling). The transition from PWM to PFM mode can be controlled by the user (A8585, A8585-1) or it can occur automatically (A8585-2, A8585-3). Both versions offer fixed output voltage options of 3.3 or 5V with ±1.0% accuracy.

Other features of the A8585 include a programmable PWM switching frequency from 300 to 550 kHz which can be synchronised to an external clock. The A8585 has external compensation to optimise stability and transient response for a wide range of external components and applications. The device has a fixed soft start time of 5 msec.

The A8585 is designed to meet the requirements of automotive and non-automotive applications, with protection features including pulse-by-pulse current limit, “hiccup” mode short-circuit protection, open/short asynchronous diode protection, boot open/short voltage protection, input undervoltage lockout, and thermal shutdown. EMI reduction features include frequency dithering and a controlled switching node.

The IC is targeted for the automotive and industrial markets with end applications to include automotive infotainment, instrumentation clusters, centre stack applications and advanced driver assistance systems. It comes in a 4.9 × 6.0 mm 10-lead SOIC package with exposed power pad.

Allegro MicroSystems; www.allegromicro.com