Automotive multi-output PMIC has buck or buck/boost pre-regulator

September 21, 2016 // By Graham Prophet
Allegro MicroSystems has added a power management IC that can be configured as a buck or buck-boost pre-regulator to efficiently convert automotive battery voltages into a tightly regulated intermediate voltage complete with control, diagnostics, and protections: it features adjustable frequency with a synchronous buck, 5V protected LDO, pulse-width window watchdog and power-on reset output.

The output of the A4413 supplies both a 5V, 75 mA maximum high-voltage protected low drop-out (LDO) regulator for remote sensors, and a 0.8 to 3.3V, 800 mA maximum adjustable synchronous buck regulator (ADJ). Designed to supply microprocessor power supplies in high-temperature environments, the device is suitable for under-hood and other automotive applications.


The A4413 can be enabled by its logic-level input (ENB) or its high-voltage input (ENBAT). Diagnostic outputs include a power-on-reset output with a 2 msec rising delay to monitor the synchronous buck, a power OK output to monitor the 5V LDO, and an ENBAT status output (ENBATS). Dual bandgaps - one for regulation and one for fault detection - improve long-term reliability of the A4413.


The product also contains a pulse-width window watchdog (PWWD) timer that can be programmed to detect pulse widths from 1 to 2 msec. The watchdog timer has an activation delay that scales with the pulse-width setting to accommodate processor startup. The tolerance of the watchdog’s window can be set to ±8%, ±13%, or ±18% using the WD pin. The watchdog timer has an active-low enable pin (WDENn) to facilitate initial factory programming or field reflash programming.


The A4413 is supplied in a low-profile 32-lead, 5 × 5 mm, 0.5 mm pitch QFN package (suffix “ET”) with exposed thermal pad.


Allegro MicroSystems;