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April 11, 2017
Allegro MicroSystems, LLC introduces a new power management IC that uses 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. The output of Allegro’s A4408 supplies a 5 V / 115 mA tracking/protected LDO, a 3.3 V / 165 mA LDO, a 5 V / 325 mA LDO, and an adjustable output synchronous buck regulator (1.25 V / 700 mA). The A4408 is ideal for under-hood applications, with key automotive applications including: Electronic Power Steering (EPS), Transmission Control Units (TCU), Advanced Braking Systems (ABS), Advanced Driver Assistance Systems (ADAS), Emissions Control Modules, and other automotive applications.
The A4408 contains a watchdog timer that can be programmed to accept a wide range of clock frequencies (WDADJ). The watchdog timer has a fixed activation delay to accommodate processor startup. The watchdog timer as an enable/disable pin (active low, WDENn) to facilitate initial factory programming or field reflash programming.
Diagnostic outputs from the A4408 include a power-on-reset output (NPOR). POK5V indicates the status of the 5 V and 5 V protected LDOs. Fault Flag 0 (FF0) and Fault Flag 1 (FF1) retain the last fault to reset the microcontroller. Dual bandgaps, one for regulation and one for fault checking, improve long-term reliability of the A4408.
Enable inputs to the A4408 include a logic-level (ENB) and two high-voltage (ENBAT1 and ENBAT2) inputs. The A4408 provides flexibility by including a TRACK pin to set the reference of the tracking regulator to either the 5 V or the 3.3 V output, so the A4408 can be adapted across multiple platforms with different sensor types. The MODE pin selects the NPOR undervoltage threshold for the V5 and V5P outputs.
Protection features include under- and overvoltage lockout on all four CPU supply rails. In case of a shorted output, all linear regulators feature foldback overcurrent 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-circuit protection, LX short-circuit protection, missing asynchronous diode protection (VREG), and thermal shutdown.
Allegro MicroSystems is redefining the future of power and sensing technologies. From green energy to advanced mobility and motion control systems, our team is passionate about developing intelligent solutions that move the world forward and give our customers a competitive edge. With global engineering, manufacturing and support, Allegro is a trusted partner to both large enterprises and regional market leaders worldwide. Visit www.allegromicro.com.