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Automotive buck/boost controller integrates buck MOSFET

9th August 2016
Nat Bowers

Designed for the automotive, industrial and instrumentation markets, an AEC-Q100 qualified PMIC has been introduced by Allegro MicroSystems Europe. The A4450 can implement either a buck or buck/boost regulator to efficiently convert automotive battery voltages into a tightly regulated voltage, with seamless transition between the buck and boost modes. Target applications include infotainment, instrument clusters, telematics, amplifiers and control modules.

Allegro’s A4450 is well-suited for automotive input environments where battery input voltage supply can vary above and below the required output voltage and a single- inductor/single-stage conversion is desired. The wide input operating voltage range of 3 to 36V makes the A4450 suitable for a range of automotive infotainment applications and handles idle stop/start, cold crank, double battery and load dump conditions. The device features a high-voltage battery compatible enable (EN) input to accommodate for switched battery input applications.

The A4450 provides regulated output voltage ranging from 3 to 8V with load current of up to 1A DC. The PWM switching frequency range is 250kHz to 2.4MHz, and frequency dithering and controlled switching transitions minimise EMI. The A4450 maintains excellent stability even when the input and output voltages are at nearly the same level as well as through line and load transient events.

Protection features include pulse-by-pulse current limit, hiccup mode short-circuit protection, LX short-circuit protection, missing freewheeling diode (buck diode at LX node in A4450). The enable input is compatible to a high-voltage battery level, and a power-on reset output (NPOR) is integrated.

The device is available in a 20-lead, 4x4mm QFN package (suffix “ES”), which is “wettable flank” and AEC-Q100 qualified.

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