Adjustable Frequency Buck or Buck-Boost Pre-Regulator with 2 LDOs, Window Watchdog Timer, and NPOR


Product Image A4409


Top Features


The A4409 is a 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 5V, 300mAMIN LDO and a 5V, 200mAMIN LDO. Designed to supply CAN or microprocessor power supplies in high-temperature environments, the A4409 is ideal for underhood applications.

Enable-input to the A4409 is compatible to a high-voltage battery level (ENBAT).

Diagnostic outputs from the A4409 include a power-on-reset output (NPOR) with a fixed 22.5ms typical delay. Dual bandgaps, one for regulation and one for fault checking, improve long-term reliability of a system designed around the A4409.

The A4409 contains a window watchdog timer that can be programmed to accept a wide range of clock frequencies (WDADJ). The watchdog timer has a fixed 30 ms 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 dual control loop for pre-regulator rail. In case of a shorted output, all linear regulators feature foldback overcurrent protection. The switching regulator includes pulse-by-pulse current limit, hiccup mode short-circuit protection, LX short-circuit protection, missing asynchronous diode protection, and thermal shutdown.

The A4409 is supplied in a low profile (1.2 mm maximum height), 20-lead eTSSOP package (suffix “LP”) with exposed thermal pad.

  • Automotive AEC-Q100 qualified
  • VIN operating range from 3 to 36 V, with 40 V maximum
  • Buck or buck-boost pre-regulator (VREG)
  • Adjustable PWM switching frequency: 250 kHz-2.4 MHz
  • PWM frequency can be synchronized to external clock
  • Two 5 V internal LDO regulators with foldback short-circuit protection
  • Power-on reset (NPOR) with fixed delay of 22.5 ms
  • Programmable window watchdog timer with a fixed activation delay of 30 ms
  • Active low, watchdog timer enable/disable pin (WDENn)
  • Dual bandgaps for increased reliability:
    • BG1 for VREG, 5V0, and VCP reference
    • BG2 for V5 reference, and VREG, 5V0, and VCP fault detection
  • Ignition-enable input (ENBAT)
  • Frequency dithering helps reduce EMI/EMC
  • Undervoltage protection for all output rails
  • Pin-to-pin and pin-to-ground tolerant at every pin
  • Thermal shutdown protection
  • −40°C to 150°C junction temperature range

Typical Applications

Provides System Power for (μC/DSP, CAN, sensors, etc.)
in Automototive Control Modules, such as:

The A4409 is supplied in a low profile (1.2 mm maximum height), 20-lead eTSSOP package (suffix “LP”) with exposed thermal pad.

LP Package Documentation

Part Number Specifications and Availability