A4490
Triple Output Step-Down Switching Regulator
Features and Benefits
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Three buck converters
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4.5 to 34 V input voltage range
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550 kHz fixed frequency
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Multiphase switching
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Independent control of each converter
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Power-on-reset flag
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Internal compensation
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4 × 4 mm QFN Package, small PCB footprint
Description
Designed to provide the power supply requirements of printers,
office automation, industrial, and portable equipment, the
A4490 provides three high current, high performance, switching
regulator outputs with independent soft start.
High frequency switching allows selection of inexpensive
inductors and small ceramic output capacitors. The turn-on
cycles of the regulators are interleaved to minimize stresses on
the input capacitors and to reduce EMI. A charge pump is used
to provide the supply for driving the power switches, ensuring
operation at very wide operating duty cycles and avoiding the
need for power-draining clamp circuits.
A power-on-reset circuit with user configurable delay indicates
when enabled regulators are in specification. The power-on-
reset flag also indicates when the input voltage drops below
specification, giving the system controller advance warning
while the switchers continue to operate down to the shutdown
level.
Internal diagnostics provide comprehensive protection against
overloads, input undervoltages, and overtemperatures.
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Package: 20-contact QFN (suffix ES)
Approximate size
Typical Application
V
BB
VDD
PORZ
CPOR
Microcontroller or
Controller Logic
CP1 CP2
VCP VBB1
LX1
V
REG1
FB1
VBB2
LX2
FB2
A4490
ENB1
ENB2
ENB3
V
REG2
PGND
VBB3
LX3
V
REG3
FB3
GND
4490-DS, Rev. 9
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
