Power management IC with boost pre-regulator

21st September 2016
Anna Flockett

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, has been announced by Allegro MicroSystems Europe.

The output of Allegro’s A4413 supplies both a 5V, 75mA maximum high-voltage protected Low Drop-Out (LDO) regulator for remote sensors, and a 0.8-3.3V, 800mA maximum Adjustable synchronous buck regulator (ADJ). Designed to supply microprocessor power supplies in high-temperature environments, the device is ideal for under-hood and other automotive applications.

This A4413 can be enabled by its logic-level input (ENB) or its high-voltage input (ENBAT). Diagnostic outputs from the new device include a power-on-reset output with a 2ms 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 1-2ms. 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.

Protection features include under- and overvoltage lockout on both output supply rails. In case of a shorted output, the LDO regulator features foldback overcurrent protection. In addition, the 5V output is protected from a short-to-battery event.  Both switching regulators include pulse-by-pulse current limit, hiccup mode short-circuit protection, LX (regulator output switching node) short-circuit protection to provide protection to the IC from damage in the case of accidental short-circuit from LX pins, missing asynchronous diode protection (VREG only), and Thermal Shutdown (TSD).

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