A4490 Triple Output Step-Down Switching Regulator Features and Benefits Description Three buck converters Designed to provide the power supply requirements of printers, 4.5 to 34 V input voltage range office automation, industrial, and portable equipment, the 550 kHz fixed frequency A4490 provides three high current, high performance, switching Multiphase switching regulator outputs with independent soft start. Independent control of each converter High frequency switching allows selection of inexpensive Power-on-reset flag inductors and small ceramic output capacitors. The turn-on Internal compensation cycles of the regulators are interleaved to minimize stresses on 4 4 mm QFN Package, small PCB footprint 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 Package: 20-contact QFN (suffix ES) 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. Continued on the next page Approximate size Typical Application V BB VDD CP1 CP2 VCP VBB1 PORZ LX1 CPOR V REG1 FB1 Microcontroller or A4490 Controller Logic VBB2 ENB1 ENB2 LX2 V ENB3 REG2 FB2 VBB3 PGND LX3 GND V REG3 FB3 4490-DS, Rev. 6A4490 Triple Output Step-Down Switching Regulator Description (continued) The A4490 is provided in a 20-contact, 4 mm 4 mm, 0.75 mm Applications include the following: nominal overall height QFN, with exposed pad for enhanced thermal Photo, inkjet, and portable printers dissipation. It is lead (Pb) free, with 100% matte tin leadframe Industrial plating. Hand-held devices Portable applications Selection Guide Operating Temperature Range Part Number Packing (C) A4490EES-T 92 pieces per tube 40 to 85 A4490EESTR-T 1500 pieces per 7-in. reel Absolute Maximum Ratings (reference to GND) Characteristic Symbol Notes Rating Units Load Supply Voltage V 36 V BB LX1, LX2, and LX3 Pins V 1 to 36 V LXn PORZ and VDD Pins V 0.3 to 7 V IN ENBx Pin Input Current I Driven by a current-limited voltage source 1 mA ENBx Operating Ambient Temperature T Range E 40 to 85 C A Maximum Junction Temperature T (max) 150 C J Storage Temperature T 55 to 150 C stg Recommended Operating Conditions Characteristic Symbol Conditions Min. Typ. Max. Units To operate at V < 6 V, connect V BB DD Load Supply Voltage V supply to the V supply. See Powering 4.5 34 V BB BB Configurations section. LX1, LX2, and LX3 Pins V 0.7 34 V LXn Operating Ambient Temperature T 40 85 C A Junction Temperature T 40 125 C J Thermal Characteristics may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions* Value Units Package Thermal Resistance R On 4-layer PCB based on JEDEC standard 37 C/W JA *Additional thermal information available on the Allegro website. Allegro MicroSystems, Inc. 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com