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.
