The A4408 is 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 the pre-regulator supplies a 5 V / 115 mAMAX tracking/protected LDO, a 3.3 V / 165 mAMAX LDO, a 5 V / 325 mAMAX LDO, and an adjustable output synchronous buck regulator (1.25 VTYP / 700 mADC). Designed to supply CAN or microprocessor power supplies in high-temperature environments, the A4408 is ideal for underhood applications.
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 sensors and supply rails. The MODE pin selects the NPOR undervoltage threshold for the V5 and V5P outputs.
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 longterm reliability of the A4408.
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 has an enable/disable pin (active low, WDENn) to facilitate initial factory programming or field reflash programming.
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.
The A4408 is supplied in a low profile (1.2 mm maximum height) 38-lead eTSSOP package (suffix “LV”) with exposed thermal pad.
