Buck/Boost Pre-Regulator with 3 LDOs

Allegro MicroSystems developed a power management integrated circuit that functions as an adjustable frequency buck or buck/boost pre-regulator with a synchronous buck, 3 LDOs, pulse-width window watchdog, NPOR and POK5V. This device converts automotive battery voltages efficiently into a tightly regulated intermediate voltage complete with control, diagnostics, and protections. The output of the pre-regulator supplies a 5 V/150 mAMAX LDO for “local” sensors (V5SNR), a 5 V / 200 mAMAX LDO for communications (V5CAN), a 5 V / 120 mAMAX tracking/ protected LDO for remote sensors (V5P), and a 0.8 V-3.3 V / 800 mAMAX adjustable synchronous buck regulator (ADJ). Designed to supply CAN or microprocessor power supplies in high temperature environments, the A4411 is ideal for under hood applications.

The A4411 can be enabled by its logic level (ENB) or high-voltage (ENBAT) input. The A4411 includes aTRACK pin to set the reference of the V5P tracking regulator to either V5SNR or the buck FBADJ pin, so the A4411 can be adapted across multiple platforms with different sensors and supply rails. Diagnostic outputs from the A4411 include a power-on-reset output (NPOR) with a fixed delay, an ENBAT status output, and a PowerOK output for the 5 V LDOs (POK5V). Dual bandgaps, one for regulation and one for fault checking, improve long-term reliability of the A4411.The A4411 contains a Pulse Width Window Watchdog (PWWD) that can be programmed to detect pulse widths from 1 ms to 2 ms (WDADJ). The watchdog 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 WDTOL pin. The watchdog has an active LOW enable pin (WDENn) to facilitate initial factory programming or field re-flash programming.

Protection features include under and over voltage lockout on all four CPU supply rails. In case of a shorted output, all linear regulators feature fold back over current protection. In addition, the V5P output is protected from a short  -to-battery event. Both switching regulators include pulse-by-pulse current limit, hiccup mode short circuion, LX short circuit protection, missing asynchronous diode protection (VREG only) and thermal shutdown.

The A44  11 is supplied in a low profile 38-lead eTSSOP package (suffix “LV”) with exposed power pad.