A4409
Adjustable Frequency Buck or Buck-Boost Pre-Regulator with
2 LDOs, Window Watchdog Timer, and NPOR
DESCRIPTION
FEATURES AND BENEFITS
• Automotive AEC-Q100 qualified
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,
completewithcontrol,diagnostics,andprotections.Theoutput
of the pre-regulator supplies a 5 V, 300 mAMIN LDO and a 5 V,
200 mAMIN LDO. Designed to supply CAN or microprocessor
power supplies in high-temperature environments, the A4409
is ideal for underhood applications.
• 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 to 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
Enable-input to the A4409 is compatible to a high-voltage
battery level (ENBAT).
• Active low, watchdog timer enable/disable pin (WDENn
• Dual bandgaps for increased reliability:
)
Diagnostic outputs from the A4409 include a power-on-reset
output (NPOR) with a fixed 22.5 ms typical delay. Dual
bandgaps,oneforregulationandoneforfaultchecking,improve
long-term reliability of a system designed around the A4409.
□ BG1 for VREG, 5V0, and VCP reference
□ BG2 for V5 reference, and VREG, 5V0, and VCP fault
detection
• Ignition-enable input (ENBAT)
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.
• 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
• −40ºC to 150ºC junction temperature range
Continued on next page...
PACKAGE: 20-Pin eTSSOP (suffix LP)
APPLICATIONS
Provides System Power for (µC/DSP, CAN, sensors, etc.)
in Automototive Control Modules, such as:
• Electronic Power Steering (EPS)
• Transmission Control Units (TCU)
• Advanced Braking Systems (ABS)
• Emissions Control Modules
Not to scale
• Other automotive applications
5 V LDO
(V5)
with Foldback
Protection
5 V LDO
(5V0)
with Foldback
Protection
6.6 V
(VREG)
Buck-Boost
Pre-Regulator
Programmable
Window Watchdog
Timer with
Bandgap 1
Bandgap 2
Thermal
Shutdown
(TSD)
NPOR
Output
Charge
Pump
Activation Delay
A4409 Simplified Block Diagram
A4409-DS, Rev. 4
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